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224 results on '"Collecte Localisation Satellites (CLS)"'

1. Interpreting C-band sea surface depolarization observations

Author: Lab-STICC_TB_CID_TOMS ; Département Image et Traitement Information (ITI) ; Télécom Bretagne - Institut Mines-Télécom - PRES Université Européenne de Bretagne (UEB) - Télécom Bretagne - Institut Mines-Télécom - PRES Université Européenne de Bretagne (UEB) - Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC) ; CNRS - Université de Bretagne Occidentale (UBO) - Université de Bretagne Sud (UBS) - Télécom Bretagne - Institut Supérieur des Sciences et Technologies de Brest (ISSTB) - ENSTA Bretagne - Institut Mines-Télécom - PRES Université Européenne de Bretagne (UEB) - Ecole Nationale d'Ingénieurs de Brest - CNRS - Université de Bretagne Occidentale (UBO) - Université de Bretagne Sud (UBS) - Institut Supérieur des Sciences et Technologies de Brest (ISSTB) - ENSTA Bretagne - Ecole Nationale d'Ingénieurs de Brest, Institut français de recherche pour l'exploitation de la mer (IFREMER) ; Ifremer, Collecte Localisation Satellites (CLS) ; entreprise, Lab-STICC_TB_CID_TOMS ; Traitement Algorithmique et Matériel de la Communication, de l'Information et de la Connaissance (TAMCIC) ; CNRS - Ecole Nationale Supérieure des Télécommunications de Bretagne - CNRS - Ecole Nationale Supérieure des Télécommunications de Bretagne - GET / ENST Bretagne ; Ecole Nationale Supérieure des Télécommunications de Bretagne - Télécom Bretagne Dept. ITI ; Télécom Bretagne - Télécom Bretagne - Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC) ; CNRS - Université de Bretagne Occidentale (UBO) - Université de Bretagne Sud (UBS) - Télécom Bretagne - Institut Supérieur des Sciences et Technologies de Brest (ISSTB) - Institut Mines-Télécom - PRES Université Européenne de Bretagne (UEB) - CNRS - Université de Bretagne Occidentale (UBO) - Université de Bretagne Sud (UBS) - Institut Supérieur des Sciences et Technologies de Brest (ISSTB) - Institut Mines-Télécom - PRES Université Européenne de Bretagne (UEB) - Département Image et Traitement Information (ITI) ; Télécom Bretagne - Institut Mines-Télécom - PRES Université Européenne de Bretagne (UEB) - Département Signal et Communications (SC) ; Télécom Bretagne - Institut Mines-Télécom - PRES Université Européenne de Bretagne (UEB) - Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC) ; CNRS - Université de Bretagne Occidentale (UBO) - Université de Bretagne Sud (UBS) - Télécom Bretagne - Institut Supérieur des Sciences et Technologies de Brest (ISSTB) - ENSTA Bretagne - Institut Mines-Télécom - PRES Université Européenne de Bretagne (UEB) - Ecole Nationale d'Ingénieurs de Brest - CNRS - ENSTA Bretagne - Ecole Nationale d'Ingénieurs de Brest, Ocean University of China, Wang, Bo, Chapron, Bertrand, Mouche, Alexis, MERCIER, Grégoire, GARELLO, René, HE, Mingxia, Lab-STICC_TB_CID_TOMS ; Département Image et Traitement Information (ITI) ; Télécom Bretagne - Institut Mines-Télécom - PRES Université Européenne de Bretagne (UEB) - Télécom Bretagne - Institut Mines-Télécom - PRES Université Européenne de Bretagne (UEB) - Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC) ; CNRS - Université de Bretagne Occidentale (UBO) - Université de Bretagne Sud (UBS) - Télécom Bretagne - Institut Supérieur des Sciences et Technologies de Brest (ISSTB) - ENSTA Bretagne - Institut Mines-Télécom - PRES Université Européenne de Bretagne (UEB) - Ecole Nationale d'Ingénieurs de Brest - CNRS - Université de Bretagne Occidentale (UBO) - Université de Bretagne Sud (UBS) - Institut Supérieur des Sciences et Technologies de Brest (ISSTB) - ENSTA Bretagne - Ecole Nationale d'Ingénieurs de Brest, Institut français de recherche pour l'exploitation de la mer (IFREMER) ; Ifremer, Collecte Localisation Satellites (CLS) ; entreprise, Lab-STICC_TB_CID_TOMS ; Traitement Algorithmique et Matériel de la Communication, de l'Information et de la Connaissance (TAMCIC) ; CNRS - Ecole Nationale Supérieure des Télécommunications de Bretagne - CNRS - Ecole Nationale Supérieure des Télécommunications de Bretagne - GET / ENST Bretagne ; Ecole Nationale Supérieure des Télécommunications de Bretagne - Télécom Bretagne Dept. ITI ; Télécom Bretagne - Télécom Bretagne - Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC) ; CNRS - Université de Bretagne Occidentale (UBO) - Université de Bretagne Sud (UBS) - Télécom Bretagne - Institut Supérieur des Sciences et Technologies de Brest (ISSTB) - Institut Mines-Télécom - PRES Université Européenne de Bretagne (UEB) - CNRS - Université de Bretagne Occidentale (UBO) - Université de Bretagne Sud (UBS) - Institut Supérieur des Sciences et Technologies de Brest (ISSTB) - Institut Mines-Télécom - PRES Université Européenne de Bretagne (UEB) - Département Image et Traitement Information (ITI) ; Télécom Bretagne - Institut Mines-Télécom - PRES Université Européenne de Bretagne (UEB) - Département Signal et Communications (SC) ; Télécom Bretagne - Institut Mines-Télécom - PRES Université Européenne de Bretagne (UEB) - Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC) ; CNRS - Université de Bretagne Occidentale (UBO) - Université de Bretagne Sud (UBS) - Télécom Bretagne - Institut Supérieur des Sciences et Technologies de Brest (ISSTB) - ENSTA Bretagne - Institut Mines-Télécom - PRES Université Européenne de Bretagne (UEB) - Ecole Nationale d'Ingénieurs de Brest - CNRS - ENSTA Bretagne - Ecole Nationale d'Ingénieurs de Brest, Ocean University of China, Wang, Bo, Chapron, Bertrand, Mouche, Alexis, MERCIER, Grégoire, GARELLO, René, and HE, Mingxia
Abstract: International audience, So far, sea surface scattering polarization sensitivity is still difficult to fully understand. To gain understanding, full polarization C-band data spectral analysis is considered and the de-polarization (HV) and polarization ratio (PR) are jointly analysed with in-situ wind and wave observations.

2. Trend and Variability of the Atmospheric Water Vapor: A Mean Sea Level Issue

Author: Laurence Eymard, Soulivanh Thao, Estelle Obligis, Bruno Picard, Centre de Recherche pour la Conservation des Collections (CRCC), Ministère de la Culture et de la Communication (MCC)-Centre National de la Recherche Scientifique (CNRS), Processus de la variabilité climatique tropicale et impacts (PARVATI), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Unité Mixte de Recherches sur les Herbivores - UMR 1213 (UMRH), VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Institut National de la Recherche Agronomique (INRA), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Centre de Recherche pour la Conservation des Collections ( CRCC ), Ministère de la Culture et de la Communication ( MCC ) -Centre National de la Recherche Scientifique ( CNRS ), Processus de la variabilité climatique tropicale et impacts ( PARVATI ), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques ( LOCEAN ), Muséum National d'Histoire Naturelle ( MNHN ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Muséum National d'Histoire Naturelle ( MNHN ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Collecte Localisation Satellites ( CLS ), Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ) -Centre National d'Etudes Spatiales ( CNES ), Unité Mixte de Recherches sur les Herbivores ( UMR 1213 Herbivores ), and VetAgro Sup ( VAS ) -AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Institut National de la Recherche Agronomique ( INRA )
Subjects: Atmospheric Science, Time series, Radiometer, Meteorology, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Microwave radiometer, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Ocean Engineering, Remote sensing, Satellite observations, Troposphere, [ PHYS.PHYS.PHYS-GEO-PH ] Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Error analysis, 13. Climate action, Environmental science, Satellite, Altimeter, Altimetry, Statistical techniques, Sea level, Water vapor, Microwave
Abstract: The wet tropospheric path delay is presently the main source of error in the estimation of the mean sea level by satellite altimetry. This correction on altimetric measurements, provided by a dedicated radiometer aboard the satellite, directly depends on the atmospheric water vapor content. Nowadays, water vapor products from microwave radiometers are rather consistent but important discrepancies remain. Understanding these differences can help improve the retrieval of water vapor and reduce at the same time the error on the mean sea level. Three radiometers are compared: the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E), Jason-1 microwave radiometer (JMR), and Envisat microwave radiometer (MWR). Water vapor products are analyzed both in terms of spatial and temporal distribution over the period 2004–10, using AMSR-E as a reference. The Interim ECMWF Re-Analysis (ERA-Interim) data are also included in the study as an additional point of comparison. Overall, the study confirms the general good agreement between the radiometers: similar patterns are observed for the spatial distribution of water vapor and the correlation of the times series is better than 0.90. However, regional discrepancies are observed and a quantitative agreement on the trend is not obtained. Regional discrepancies are driven by the annual cycle. The JMR product shows discrepancies are highly dependent on water vapor, which might be related to calibration issues. Furthermore, triple collocation analysis suggests a possible drift of JMR. MWR discrepancies are located in coastal regions and follow a seasonal dynamic with stronger differences in summer. It may result from processing of the brightness temperatures.
Published: 2014
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3. Hydrological modelling on atmospheric grids: using graphs of sub-grid elements to transport energy and water

Author: Jan Polcher, Anthony Schrapffer, Eliott Dupont, Lucia Rinchiuso, Xudong Zhou, Olivier Boucher, Emmanuel Mouche, Catherine Ottlé, Jérôme Servonnat, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols (METIS), École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Instituto Franco-Argentino sobre Estudios de Clima y sus Impactos [Buenos Aires] (IFAECI), Centro de Investigaciones del Mar y la Atmósfera (CIMA), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Facultad de Ciencias Exactas y Naturales [Buenos Aires] (FCEyN), Universidad de Buenos Aires [Buenos Aires] (UBA)-Universidad de Buenos Aires [Buenos Aires] (UBA)-Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Facultad de Ciencias Exactas y Naturales [Buenos Aires] (FCEyN), Universidad de Buenos Aires [Buenos Aires] (UBA)-Universidad de Buenos Aires [Buenos Aires] (UBA)-Centre National de la Recherche Scientifique (CNRS), and The University of Tokyo (UTokyo)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU]Sciences of the Universe [physics], General Medicine, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment
Abstract: Land surface models (LSMs) use the atmospheric grid as their basic spatial decomposition because their main objective is to provide the lower boundary conditions to the atmosphere. Lateral water flows at the surface on the other hand require a much higher spatial discretization as they are closely linked to topographic details. We propose here a methodology to automatically tile the atmospheric grid into hydrological coherent units which are connected through a graph. As water is transported on sub-grids of the LSM, land variables can easily be transferred to the routing network and advected if needed. This is demonstrated here for temperature. The quality of the river networks generated, as represented by the connected hydrological transfer units, are compared to the original data in order to quantify the degradation introduced by the discretization method. The conditions the sub-grid elements impose on the time step of the water transport scheme are evaluated, and a methodology is proposed to find an optimal value. Finally the scheme is applied in an off-line version of the ORCHIDEE (Organising Carbon and Hydrology In Dynamic Ecosystems) LSM over Europe to show that realistic river discharge and temperatures are predicted over the major catchments of the region. The simulated solutions are largely independent of the atmospheric grid used thanks to the proposed sub-grid approach.
Published: 2023
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4. Including antenna mispointing in a semi-analytical model for delay/Doppler altimetry

Author: François Boy, Corinne Mailhes, Jean-Yves Tourneret, Thomas Moreau, Abderrahim Halimi, Centre National d'Études Spatiales - CNES (FRANCE), Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Université Toulouse - Jean Jaurès - UT2J (FRANCE), Université Toulouse 1 Capitole - UT1 (FRANCE), Collecte Localisation Satellites - CLS (FRANCE), Laboratoire de recherche en télécommunications spatiales et aéronautiques - TéSA (FRANCE), Signal et Communications (IRIT-SC), Institut de recherche en informatique de Toulouse (IRIT), Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées, Télécommunications Spatiales et Aéronautiques - Telecommunications for Space ant Aeronautics (TéSA), Laboratoire de recherche coopératif dans les télécommunications spatiales et aéronautiques (TESA), CoMputational imagINg anD viSion (IRIT-MINDS), Institut National Polytechnique (Toulouse) (Toulouse INP), Centre National d'Études Spatiales [Toulouse] (CNES), Collecte Localisation Satellites (CLS), and Centre National d'Études Spatiales [Toulouse] (CNES)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)
Subjects: Least squares estimation, Cryosat, 010504 meteorology & atmospheric sciences, Computer science, 0211 other engineering and technologies, Réseaux et télécommunications, Antenna mispointing, 02 engineering and technology, 01 natural sciences, Least squares, Radiation pattern, Convolution, law.invention, symbols.namesake, [INFO.INFO-NI]Computer Science [cs]/Networking and Internet Architecture [cs.NI], law, Altimeter, Electrical and Electronic Engineering, Radar, Point target, Impulse response, SAR altimetry, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, Scattering, Delay/Doppler map, Geodesy, symbols, General Earth and Planetary Sciences, Antenna (radio), Altimetry, Doppler effect, Algorithm
Abstract: International audience; Delay/Doppler altimetry aims at reducing the measurementnoise and increasing the along-track resolution in comparison with conventional pulse limited altimetry. In a previous paper, we have proposed a semi-analytical model for delay/Doppler altimetry which considers some simplifications as the absence of mispointing antenna. This paper first proposes a new semi-analytical model for delay/Doppler altimetry. The proposed analytical expression for the flat surface impulse response considers antenna mispointing angles, a circular antenna pattern, no vertical speed effect and a uniform scattering. The two dimensional delay/Doppler map is obtained by a numerical computation of the convolution between the proposed analytical function, the probability density function of the heights of the specular scatterers and the time/frequency point target response of the radar. The approximations used to obtain the semi-analytical model are analyzed and the associated errors are quantified by analytical bounds for these errors. The second contribution of this paper concerns the estimation of the parameters associated with the multi-look semi-analytical model. Two estimation strategies based on the least squares procedure are proposed. The proposed model and algorithms are validated on both synthetic and real waveforms. The obtained results are very promising and show the accuracy of this generalized model with respect to the previous model assuming zero antenna mispointing.
Published: 2015
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5. SARAL/AltiKa Wet Tropospheric Correction: In-Flight Calibration, Retrieval Strategies and Performances

Author: Marie-Laure Frery, Bruno Picard, Nathalie Steunou, Estelle Obligis, Nicolas Picot, Laurence Eymard, Unité Mixte de Recherches sur les Herbivores ( UMR 1213 Herbivores ), VetAgro Sup ( VAS ) -AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Institut National de la Recherche Agronomique ( INRA ), Collecte Localisation Satellites ( CLS ), Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ) -Centre National d'Etudes Spatiales ( CNES ), Processus de la variabilité climatique tropicale et impacts ( PARVATI ), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques ( LOCEAN ), Muséum National d'Histoire Naturelle ( MNHN ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Muséum National d'Histoire Naturelle ( MNHN ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Institut Lavoisier de Versailles ( ILV ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Centre National de la Recherche Scientifique ( CNRS ), Centre National d'Etudes Spatiales ( CNES ), Unité Mixte de Recherches sur les Herbivores - UMR 1213 (UMRH), VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Institut National de la Recherche Agronomique (INRA), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Processus de la variabilité climatique tropicale et impacts (PARVATI), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN), Institut Lavoisier de Versailles (ILV), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Centre National d'Études Spatiales [Toulouse] (CNES), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)
Subjects: Brightness, Radiometer, 010504 meteorology & atmospheric sciences, Meteorology, Microwave radiometer, 0211 other engineering and technologies, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 02 engineering and technology, Oceanography, 01 natural sciences, Troposphere, Geography, [ PHYS.PHYS.PHYS-GEO-PH ] Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Calibration, Range (statistics), data quality, Altimeter, microwave radiometry, Empirical relationship, wet tropospheric correction, Altimetry, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, Remote sensing
Abstract: International audience; The SARAL/AltiKa mission is a complement of the Jason altimeter series. A two-channels (23.8 GHz and 37 GHz) microwave radiometer (MWR) is combined to the altimeter in order to correct the altimeter range for the excess path delay (referred as WTC for wet tropospheric correction. First, the in-flight calibration of AltiKa MWR is assessed from a systematic comparison to other radiometers using a complete set of metrics (comparison to simulations and over geophysical targets). Then the “mixed” empirical approach successfully used for Envisat shows nonoptimal performances for the WTC retrieval. In order to find the potential sources of issues, this method is compared to a purely empirical relationship established between measured brightness temperatures (TB) and altimeter backscattering coefficient ($\sigma_{0}$) on one hand and modeled WTC on the other hand. Various retrieval configurations for both AltiKa MWR and advanced microwave radiometer (AMR) on Jason-2, are for the first time systematically compared with respect to their performances against the variance of sea surface height differences at crossovers. Finally, the issues on the “mixed” approach are attributed to the differences between simulated and measured at Ka-band. Now, a configuration of the empirical approach proved to have performances closed to what is initially expected with the “mixed” approach.
Published: 2015
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6. Simultaneous estimation of ocean mesoscale and coherent internal tide sea surface height signatures from the global altimetry record

Author: Loren Carrere, Maxime Ballarotta, Frederic Briol, Florent Lyard, Gérald Dibarboure, Chloé Durand, Clement Ubelmann, Yannice Faugère, Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Centre National d'Études Spatiales [Toulouse] (CNES), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
Subjects: Aliasing, [SDU]Sciences of the Universe [physics], Conjugate gradient method, Internal tide, Mesoscale meteorology, Sampling (statistics), Inversion (meteorology), Sea-surface height, Altimeter, Geodesy, Geology, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography
Abstract: This study proposes an approach to estimate the ocean sea surface height signature of coherent internal tides from a 25-year along-track altimetry record, with a single inversion over time, resolving both internal tide contributions and mesoscale eddy variability. The inversion is performed on a reduced-order basis of topography and practically achieved with a conjugate gradient. The particularity of this approach is to mitigate the potential aliasing effects between mesoscales and internal tide estimation from the uneven altimetry sampling (observing the sum of these components) by accounting for their statistics simultaneously, while other methods generally use a prior mesoscale. The four major tidal components are considered (M2, K1, S2, O1) over the period 1992–2017 on a global configuration. From the solution, we use altimetry data after 2017 for independent validation in order to evaluate the performance of the simultaneous inversion and compare it with an existing model.
Published: 2022
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7. The challenge of assessing the effects of drifting fish aggregating devices on the behaviour and biology of tropical tuna

Author: Dagorn, Laurent, Dupaix, Amaël, Filmalter, John, Baidai, Yannick, Bodin, Nathalie, Capello, Manuela, Chassot, Emmanuel, Demarcq, Hervé, Deneubourg, Jean-Louis, Fonteneau, Alain, Forget, Fabien, Forrestal, Francesca, Gaertner, Daniel, Hall, Martin, Holland, Kim, Itano, David, Kaplan, David, Lopez, Jon, Marsac, Francis, Maufroy, Alexandra, Moreno, Gala, Muir, Jeff, Murua, Hilario, Roa-Pascuali, Liliana, Pérez, Géraldine, Restrepo, Victor, Robert, Marianne, Schaefer, Kurt, Sempo, Grégory, Soria, Marc, Ménard, Frédéric, MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), South African Institute for Aquatic Biodiversity (SAIAB), National Research Foundation [South Africa] (NRF), African Marine Expertise, Seychelles Fishing Authority (SFA) (SFA), Université des Seychelles, Sustainable Ocean Seychelles (SOS), Indian Ocean Tuna Commission (IOTC), CENOLI, Université Libre de Bruxelles, Université libre de Bruxelles (ULB), Consulant, Saint-Malo, Southeast Fisheries Science Center (SEFC), NOAA National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)-National Oceanic and Atmospheric Administration (NOAA), Inter-American Tropical Tuna Commission (IATTC), Hawai'i Institute of Marine Biology (HIMB), Opah Consulting, ORTHONGEL, International Seafood Sustainability Foundation (ISSF), Collecte Localisation Satellites (CLS), Institut Océanographique Paul Ricard, Six-Fours-les-Plages, France, Dynamique et durabilité des écosystèmes : de la source à l’océan (DECOD), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), and Aix Marseille Univ., Université de Toulon, CNRS, IRD, Mediterranean Institute of Oceanography
Subjects: ecological effects, fisheries management, tuna, [SDV.SA.STP]Life Sciences [q-bio]/Agricultural sciences/Sciences and technics of fishery, fish behaviour, ecological trap, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, DFAD
Abstract: Though fisheries have intensively used drifting fish aggregating devices (DFADs) over the last three decades to facilitate their catch of tropical tunas, assessing the consequences of the presence of DFADs at sea on tuna behaviour and biology is a challenge. The use of DFADs has resulted in a major increase in the number of floating objects, which are spatially heterogeneous at sea. To date, no scientific consensus exists regarding the effects of DFADs on the large-scale movements and behaviour of tuna, mainly due to the difficulty of disentangling the respective roles of DFADs and environmental factors. Some biological indices show that tuna condition is lower when associated to a floating object than in a free-swimming school. It is not possible, however, to elucidate whether this is the cause or result of the association, or if it affects the fitness of individuals in the long term. Further scientific progress would require (i) the collection of time series of indicators to monitor habitat change, individual behaviour, individual fitness and population dynamics, and (ii) experimental studies to identify the underlying behavioural and biological processes involved the associative behaviour. The extent of the modification of the surface habitat by the massive deployment of DFADs and the current uncertainty of the possible long-term consequences on the individual fitness and dynamics of tuna populations argue for the need for increased awareness of this issue by Regional Fisheries Management Organisations regulating tuna fishing.
Published: 2023

8. Reduction of rain-induced errors for wind speed estimation on SAR observations using convolutional neural networks

Author: Colin, Aurélien, Tandeo, Pierre, Peureux, Charles, Husson, Romain, Fablet, Ronan, Equipe Observations Signal & Environnement (Lab-STICC_OSE), Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT), Département Mathematical and Electrical Engineering (IMT Atlantique - MEE), IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Océan Dynamique Observations Analyse (ODYSSEY), Université de Bretagne Occidentale - UFR Sciences et Techniques (UBO UFR ST), Université de Brest (UBO)-Université de Brest (UBO)-Université de Rennes (UR)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-IMT Atlantique (IMT Atlantique), Collecte Localisation Satellites (CLS), and Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES)
Subjects: FOS: Computer and information sciences, Physics - Atmospheric and Oceanic Physics, Deep Learning, Computer Vision and Pattern Recognition (cs.CV), Atmospheric and Oceanic Physics (physics.ao-ph), [SDE]Environmental Sciences, Computer Science - Computer Vision and Pattern Recognition, FOS: Physical sciences, Wind, Oceanography, Synthetic Aperture Radar
Abstract: Synthetic Aperture Radar is known to be able to provide high-resolution estimates of surface wind speed. These estimates usually rely on a Geophysical Model Function (GMF) that has difficulties accounting for non-wind processes such as rain events. Convolutional neural network, on the other hand, have the capacity to use contextual information and have demonstrated their ability to delimit rainfall areas. By carefully building a large dataset of SAR observations from the Copernicus Sentinel-1 mission, collocated with both GMF and atmospheric model wind speeds as well as rainfall estimates, we were able to train a wind speed estimator with reduced errors under rain. Collocations with in-situ wind speed measurements from buoys show a root mean square error that is reduced by 27% (resp. 45%) under rainfall estimated at more than 1 mm/h (resp. 3 mm/h). These results demonstrate the capacity of deep learning models to correct rain-related errors in SAR products., Comment: 11 pages, 9 figures
Published: 2023
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9. Southern Ocean Ice-Covered Eddy Properties From Satellite Altimetry

Author: Matthis Auger, Jean‐Baptiste Sallée, Andrew F. Thompson, Etienne Pauthenet, Pierre Prandi, Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), University of Tasmania [Hobart, Australia] (UTAS), Processus et interactions de fine échelle océanique (PROTEO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), California Institute of Technology (CALTECH), Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), and European Project: 821001,SO-CHIC(2019)
Subjects: Geophysics, Space and Planetary Science, Geochemistry and Petrology, [SDU]Sciences of the Universe [physics], Earth and Planetary Sciences (miscellaneous), Earth Science, Oceanography
Abstract: International audience; We investigate statistical properties of surface currents as well as coherent mesoscale eddies in the seasonally ice-covered Southern Ocean. Based on a recent regional Sea Level Anomaly satellite altimetry data set, we compute Eddy Kinetic Energy (EKE) and detect mesoscale eddies. EKE is about one order of magnitude higher in the northern sector of the subpolar basin and over the continental slope, as compared to the middle of the subpolar gyres. An eddy detection methodology reveals that eddies are distributed evenly in the subpolar Southern Ocean, and their amplitude follows the spatial pattern of EKE. In addition to regional circulation variations, sea ice concentration arises as an important driver of eddy properties. Eddies have low amplitude and density in the pack ice, in particular in the middle of the gyres where the background circulation is unfavorable for instabilities. In contrast, the northern part of the Marginal Ice Zone is favorable for mesoscale eddies, especially cyclonic. There, eddies are stronger and their density is higher than in any other region of the ice-covered or ice-free subpolar Southern Ocean. This region is expected to be a site of frontogenesis due to sea ice melt and upwelling generated from interactions between the wind and the sea ice. While many mesoscale eddies will fall below detection level due to the small Rossby radius at high latitudes, these results contribute to understanding the interactions between mesoscale eddies, sea ice, and the background circulation in the subpolar region.
Published: 2023
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10. Southern ocean sea level anomaly in the sea ice-covered sector from multimission satellite observations

Author: Matthis Auger, Pierre Prandi, Jean-Baptiste Sallée, Processus et interactions de fine échelle océanique (PROTEO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), and European Project: 821001,SO-CHIC(2019)
Subjects: Statistics and Probability, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Library and Information Sciences, Statistics, Probability and Uncertainty, Computer Science Applications, Education, Information Systems
Abstract: Despite its central role in the global climate, the Southern Ocean circulation is still one of the least understood ocean circulation systems of the planet. One major constraint to our understanding of this region is the challenge of observing ocean circulation in the seasonally sea ice sector of the Southern Ocean. Here, we present a new Sea Level Anomaly (SLA) product, focusing on the subpolar Southern Ocean and including its sea ice covered parts from 2013 to 2019. Combining observations from multiple satellites, including Cryosat-2, Sentinel-3A, and SARAL/AltiKa, processed with state-of-the-art algorithms, allows an improvement in spatial and temporal resolution compared with previous products. Validation is made by comparing our estimate with existing SLA products, cross-comparing estimates from individual satellites in the sea ice zones, and comparing the time series of the product with a Bottom Pressure Recorder in the Drake Passage.
Published: 2022
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11. Parameter estimation for peaky altimetric waveforms

Author: François Boy, Corinne Mailhes, Pierre Thibaut, Abderrahim Halimi, J.-Y. Tourneret, Centre National d'Études Spatiales - CNES (FRANCE), Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - INPT (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Collecte Localisation Satellites - CLS (FRANCE), Signal et Communications (IRIT-SC), Institut de recherche en informatique de Toulouse (IRIT), Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées, Institut National Polytechnique (Toulouse) (Toulouse INP), Collecte Localisation Satellites (CLS), Centre National d'Études Spatiales [Toulouse] (CNES)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Centre National d'Études Spatiales [Toulouse] (CNES), and Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Subjects: 010504 meteorology & atmospheric sciences, Brown model, Gaussian, 0211 other engineering and technologies, Coastal altimetry, 02 engineering and technology, Sea state, 01 natural sciences, Physics::Geophysics, symbols.namesake, Cramér-Rao bounds, Bias of an estimator, [INFO.INFO-TS]Computer Science [cs]/Signal and Image Processing, Traitement du signal et de l'image, 14. Life underwater, Electrical and Electronic Engineering, Cramér–Rao bounds, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, Remote sensing, Mathematics, Estimation theory, Estimator, Geodesy, Peaks, Amplitude, Parametric model, symbols, General Earth and Planetary Sciences, Cramér–Rao bound, [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing, Maximum likelihood
Abstract: International audience; Much attention has been recently devoted to the analysis of coastal altimetric waveforms. When approaching the coast, altimetric waveforms are sometimes corrupted by peaks caused by high reflective areas inside the illuminated land surfaces or by the modification of the sea state close to the shoreline. This paper introduces a new parametric model for these peaky altimetric waveforms. This model assumes that the received altimetric waveform is the sum of a Brown echo and an asymmetric Gaussian peak. The asymmetric Gaussian peak is parameterized by a location, an amplitude, a width, and an asymmetry coefficient. A maximum-likelihood estimator is studied to estimate the Brown plus peak model parameters. The Cramér-Rao lower bounds of the model parameters are then derived providing minimum variances for any unbiased estimator, i.e., a reference in terms of estimation error. The performance of the proposed model and the resulting estimation strategy are evaluated via many simulations conducted on synthetic and real data. Results obtained in this paper show that the proposed model can be used to retrack efficiently standard oceanic Brown echoes as well as coastal echoes corrupted by symmetric or asymmetric Gaussian peaks. Thus, the Brown with Gaussian peak model is useful for analyzing altimetric easurements closer to the coast.
Published: 2013
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12. Tide gauge-based sea level variations since 1950 along the Norwegian and Russian coasts of the Arctic Ocean: Contribution of the steric and mass components

Author: Henry , Olivier, Prandi , Pierre, Llovel , William, Cazenave , Anny, Jevrejeva , Svetlana, Stammer , Detlef, Meyssignac , Benoit, Koldunov , Nikolay V., Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Collecte Localisation Satellites (CLS), Centre National d'Études Spatiales [Toulouse] (CNES)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, National Oceanography Centre [Southampton] (NOC), University of Southampton, Institute of Marine Sciences, University of Hamburg, Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), NASA-California Institute of Technology (CALTECH), Laboratoire d'études en Géophysique et océanographie spatiales ( LEGOS ), Université Paul Sabatier - Toulouse 3 ( UPS ) -Centre National d'Etudes Spatiales ( CNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), Collecte Localisation Satellites ( CLS ), Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ) -Centre National d'Etudes Spatiales ( CNES ), Jet Propulsion Laboratory ( JPL ), NASA-California Institute of Technology ( CALTECH ), National Oceanography Centre [Southampton] ( NOC ), and University of Southampton [Southampton]
Subjects: [ SDU.OCEAN ] Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere
Abstract: International audience; We investigate sea level change and variability in part of the Arctic region over the 1950-2009 period. Analysis of 62 long tide gauge records along the Norwegian and Russian coastlines shows that coastal mean sea level in these two areas was almost stable until about 1980 but since then displayed a clear increasing trend, following fluctuations of Arctic Oscillation. After the mid-to-late 1990s the co-fluctuation with the AO disappears, to achieve an increasing trend of ~4 mm/yr since 1995. Using in situ ocean temperature and salinity data from three different databases, we estimated the thermosteric, halosteric and steric sea level since 1970 in the North Atlantic and Nordic Seas region (incomplete data coverage prevented us to analyze steric data along the Russian coast). We note a strong anti-correlation between the thermosteric and halosteric components both in terms of spatial trends and regionally averaged time series. The latter show a strong change as of ~1995 that indicates increase in temperature and salinity, confirmed by the Empirical Orthogonal Function decomposition. Regionally steric data are compared to altimetry-based sea level over 1993-2009. Spatial trend patterns of altimetry-based sea level are largely explained by steric patterns, but residual spatial trends suggest that other factors contribute. Focusing on Norwegian tide gauges, we compare observed coastal mean sea level with the steric sea level and the ocean mass component estimated with GRACE gravimetry data (since 2003) and conclude that the mass component partly explains the sustained sea level rise (of ~4 mm/yr) over the altimetry era.
Published: 2012
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13. New Observations From the SWIM Radar On-Board CFOSAT: Instrument Validation and Ocean Wave Measurement Assessment

Author: L. Oruba, D. Alraddawi, Emmanuel Dormy, G. Guitton, Céline Tison, R. Rodriguez Suquet, Laura Hermozo, Romain Husson, Victor Gressani, Annabelle Ollivier, Danièle Hauser, Patricia Schippers, F. Piras, B. Chapron, Antoine Grouazel, N. Tran, Alice Dalphinet, Alexey Mironov, Lauriane Delaye, F. Gouillon, Alexis Mouche, M. Dalila, L. Aouf, Cedric Tourain, SPACE - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Centre National d'Études Spatiales [Toulouse] (CNES), Météo France, Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Analytic and Computational Research, Inc. - Earth Sciences (ACRI-ST), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), OceanDataLab, Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), CNES, CNRS, Ifremer,..., Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Météo-France Direction Interrégionale Sud-Est (DIRSE), Météo-France, Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER)
Subjects: ocean wave spectra, Radar measurements, 0211 other engineering and technologies, 02 engineering and technology, spaceborne radar, altimeter, law.invention, Wave model, law, Wind wave, Nadir, 14. Life underwater, Altimeter, Electrical and Electronic Engineering, Radar, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Physics::Atmospheric and Oceanic Physics, 021101 geological & geomatics engineering, Remote sensing, Sea surface, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, radar measurements, speckle noise, Index Terms-Radar measurements, Spaceborne radar, Scatterometer, Surface waves, Surface wave, General Earth and Planetary Sciences, sea surface, scatterometer, Instruments, Significant wave height, Radar cross-sections, Geology
Abstract: International audience; This paper describes first results obtained from the SWIM (Surface Waves Investigation and Monitoring) instrument carried by CFOSAT (China France Oceanography Satellite), which was launched on October 29th, 2018. SWIM is a Ku-Band radar with a near-nadir scanning beam geometry. It was designed to measure the spectral properties of surface ocean waves. First, the good behavior of the instrument is illustrated. It is then shown that the nadir products (significant wave height, normalized radar cross-section and wind speed) exhibit an accuracy similar to standard altimeter missions, thanks to a new retracking algorithm, which compensates a lower sampling rate compared to standard altimetry missions. The off-nadir beam observations are analyzed in details. The normalized radar cross-section varies with incidence and wind speed as expected from previous studies presented in the literature. We illustrate that, in order to retrieve the wave spectra from the radar backscattering fluctuations, it is crucial to apply a speckle correction derived from the observations. Directional spectra of ocean waves and their mean parameters are then compared to wave model data at the global scale and to in situ data from a selection of case studies. The good efficiency of SWIM to provide the spectral properties of ocean waves in the wavelength range [70m-500m] is illustrated. The main limitations are discussed, and the perspectives to improve data quality are presented.
Published: 2021
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14. Sea‐ice detection from near‐nadir Ku‐band echoes from CFOSAT/SWIM scatterometer

Author: Charles Peureux, Nicolas Longépé, Alexis Mouche, Céline Tison, Cédric Tourain, Jean‐Michel Lachiver, Danièle Hauser, Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), European Space Research Institute (ESRIN), Agence Spatiale Européenne = European Space Agency (ESA), Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Centre National d'Études Spatiales [Toulouse] (CNES), SPACE - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), European Space Agency (ESA), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, sea-ice, Ocean Surface Wind, 010504 meteorology & atmospheric sciences, Ocean Surface Waves, Sea Ice, SWIM, CFOSAT, Environmental Science (miscellaneous), 010502 geochemistry & geophysics, 01 natural sciences, CFOSAT Mission, Physics::Geophysics, Geophysical Model Function, General Earth and Planetary Sciences, SWIM Radar, 14. Life underwater, Astrophysics::Earth and Planetary Astrophysics, Scatterometer, Physics::Atmospheric and Oceanic Physics, Geophysical Model Function GMF, 0105 earth and related environmental sciences
Abstract: International audience; SWIM on board CFOSAT is the first spaceborne, low incidence, rotating scatterometer, aiming at measuring in near-real time ocean waves spectra. With 5 off-nadir beams at incidences between 2 • and 10 • plus one nadir beam, it covers the Earth in 13 days, including polar regions thanks to its polar orbit. This work aims at exploiting the SWIM data over ice regions with two objectives. An off-nadir data-based sea-ice flag is here proposed that allows, first, to eliminate sea-ice polluted echoes for improving the wave spectrum retrieval, and second, to open perspectives for application of sea-ice monitoring with near nadir Ku-band active sensors. To this end, the signature of both open water and sea-ice radar backscatter is parameterized into Geophysical Model Functions. Then, comparisons with observed profiles through a Bayesian scheme provide a probability of sea-ice presence. After comparison with both model (ECMWF-IFS) and radiometer (SSMI) derived reference data sets, the proposed flag is found to be ready for operational use. At latitudes greater than 40 • in absolute value, the proposed flagging algorithm exhibits accuracies of approximately 98% for all beams compared to SSMI data. Beam to beam performances are characterized and show potential for the characterization of sea-ice at Ku band.
Published: 2022
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15. Sea level along the world’s coastlines can be measured by a network of virtual altimetry stations

Author: Anny Cazenave, Yvan Gouzenes, Florence Birol, Fabien Leger, Marcello Passaro, Francisco M. Calafat, Andrew Shaw, Fernando Nino, Jean François Legeais, Julius Oelsmann, Marco Restano, Jérôme Benveniste, Deutsches Geodätisches Forschungsinstitut (DGFI-TUM), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Collecte Localisation Satellites (CLS), and Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES)
Subjects: [SDU]Sciences of the Universe [physics], General Earth and Planetary Sciences, ddc, General Environmental Science
Abstract: For nearly 30 years, space-based radar altimetry has been routinely measuring changes in sea level at global and regional scales. But this technique designed for the open ocean does not provide reliable sea level data within 20 km to the coast, mostly due to land contamination within the radar echo in the vicinity of the coast. This problem can now be overcome through dedicated reprocessing, allowing the retrieval of valid sea level data in the 0-20 km band from the coast, and then the access to novel information on sea level change in the world coastal zones. Here we present sea level anomalies and associated coastal sea level trends at 756 altimetry-based virtual coastal stations located along the coasts of North and South America, Northeast Atlantic, Mediterranean Sea, Africa, North Indian Ocean, Asia and Australia. This new dataset, derived from the reprocessing of high-resolution (300 m) along-track altimetry data from the Jason-1, 2 and 3 missions from January 2002 to December 2019, allows the analysis of the decadal evolution of coastal sea level and fills the coastal gap where sparse sea level information is currently available.
Published: 2022
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16. Global-Scale Environmental Niche and Habitat of Blue Shark (Prionace glauca) by Size and Sex: A Pivotal Step to Improving Stock Management

Author: Jean-Noël Druon, Steven Campana, Frederic Vandeperre, Fábio H. V. Hazin, Heather Bowlby, Rui Coelho, Nuno Queiroz, Fabrizio Serena, Francisco Abascal, Dimitrios Damalas, Michael Musyl, Jon Lopez, Barbara Block, Pedro Afonso, Heidi Dewar, Philippe S. Sabarros, Brittany Finucci, Antonella Zanzi, Pascal Bach, Inna Senina, Fulvio Garibaldi, David W. Sims, Joan Navarro, Pablo Cermeño, Agostino Leone, Guzmán Diez, María Teresa Carreón Zapiain, Michele Deflorio, Evgeny V. Romanov, Armelle Jung, Matthieu Lapinski, Malcolm P. Francis, Humberto Hazin, Paulo Travassos, Agencia Estatal de Investigación (España), European Commission - Joint Research Centre [Ispra] (JRC), Universidade dos Açores, Hopkins Marine Station [Stanford], Stanford University, Departamento de Oceanografia e Pescas [Horta], Instituto do Mar - Universidade dos Açores (IMAR-UAc), MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Collecte Localisation Satellites (CLS), Universidade Federal Rural de Pernambuco (UFRPE), Druon, JN, Campana, S, Vandeperre, F, Hazin, FHV, Bowlby, H, Coelho, R, Queiroz, N, Serena, F, Abascal, F, Damalas, D, Musyl, M, Lopez, J, Block, B, Afonso, P, Dewar, H, Sabarros, PS, Finucci, B, Zanzi, A, Bach, P, Senina, I, Garibaldi, F, Sims, DW, Navarro, J, Cermeno, P, Leone, A, Diez, G, Zapiain, MTC, Deflorio, M, Romanov, EV, Jung, ARL, Lapinski, M, Francis, MP, Hazin, H, and Travassos, P
Subjects: foraging habitat, habitat niche, chlorophyll-a gradient, marine productivity, mesotrophic, oligotrophic, mesopelagic micronekton, water temperature, Global and Planetary Change, Mesotrophic, [SDE.MCG]Environmental Sciences/Global Changes, Chlorophyll-a gradient, Marine productivity, Ocean Engineering, Aquatic Science, Oceanography, Foraging habitat, Oligotrophic, Habitat niche, Water temperature, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Conserve and sustainably use the oceans, seas and marine resources for sustainable development, Mesopelagic micronekton, Water Science and Technology
Abstract: 25 pages, 10 figures, 2 tables, supplementary material https://www.frontiersin.org/articles/10.3389/fmars.2022.828412/full#supplementary-material.-- Data Availability Statement: The blue shark habitat data are available on the JRC Data Catalogue (https://data.jrc.ec.europa.eu/dataset?q=fish%20habitat) (or upon request) and habitat maps are available online (https://fishreg.jrc.ec.europa.eu/web/fish-habitat/habitatmapping). Chlorophyll-a data are available online (https://oceancolor.gsfc.nasa.gov/cgi/l3). The abiotic environmental and mesopelagic micronekton data are available online (https://marine.copernicus.eu/access-data)., Blue shark (Prionace glauca) is amongst the most abundant shark species in international trade, however this highly migratory species has little effective management and the need for spatio-temporal strategies increases, possibly involving the most vulnerable stage or sex classes. We combined 265,595 blue shark observations (capture or satellite tag) with environmental data to present the first global-scale analysis of species’ habitat preferences for five size and sex classes (small juveniles, large juvenile males and females, adult males and females). We leveraged the understanding of blue shark biotic environmental associations to develop two indicators of foraging location: productivity fronts in mesotrophic areas and mesopelagic micronekton in oligotrophic environments. Temperature (at surface and mixed layer depth plus 100 m) and sea surface height anomaly were used to exclude unsuitable abiotic environments. To capture the horizontal and vertical extent of thermal habitat for the blue shark, we defined the temperature niche relative to both sea surface temperature (SST) and the temperature 100 m below the mixed layer depth (Tmld+100). We show that the lifetime foraging niche incorporates highly diverse biotic and abiotic conditions: the blue shark tends to shift from mesotrophic and temperate surface waters during juvenile stages to more oligotrophic and warm surface waters for adults. However, low productivity limits all classes of blue shark habitat in the tropical western North Atlantic, and both low productivity and warm temperatures limit habitat in most of the equatorial Indian Ocean (except for the adult males) and tropical eastern Pacific. Large females tend to have greater habitat overlap with small juveniles than large males, more defined by temperature than productivity preferences. In particular, large juvenile females tend to extend their range into higher latitudes than large males, likely due to greater tolerance to relatively cold waters. Large juvenile and adult females also seem to avoid areas with intermediate SST (~21.7-24.0°C), resulting in separation from large males mostly in the tropical and temperate latitudes in the cold and warm seasons, respectively. The habitat requirements of sensitive size- and sex-specific stages to blue shark population dynamics are essential in management to improve conservation of this near-threatened species, With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)
Published: 2022
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17. Measuring ocean total surface current velocity with the KuROS and KaRADOC airborne near-nadir Doppler radars: a multi-scale analysis in preparation for the SKIM mission

Author: Marié, Louis, Pineau-Gouillou, Lucia, Monnier, Goulwenn, Collard, Fabrice, Nouguier, Frédéric, Pineau-Guillou, Lucia, Hauser, Danièle, Boy, François, Méric, Stéphane, Sutherland, Peter, Peureux, Charles, Monnier, Goulven, Chapron, Bertrand, Martin, Adrien, Dubois, Pierre, Donlon, Craig, Casal, Tania, Ardhuin, Fabrice, Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), L@b SCALIAN, OceanDataLab, SPACE - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Centre National d'Études Spatiales [Toulouse] (CNES), Institut d'Électronique et des Technologies du numéRique (IETR), Nantes Université (NU)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), National Oceanography Centre [Southampton] (NOC), University of Southampton, Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), DRIFT4SKIM, European Space Agency, Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Sorbonne Université (SU), Centre National de la Recherche Scientifique (CNRS)-CentraleSupélec-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Nantes (UN), Centre National d'Études Spatiales [Toulouse] (CNES)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Agence Spatiale Européenne = European Space Agency (ESA), and Université de Nantes (UN)-Université de Rennes 1 (UR1)
Subjects: 010504 meteorology & atmospheric sciences, 0211 other engineering and technologies, 02 engineering and technology, Sea state, 01 natural sciences, Wind speed, law.invention, symbols.namesake, law, 14. Life underwater, Radar, Physics::Atmospheric and Oceanic Physics, lcsh:Environmental sciences, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:GE1-350, Ocean current, lcsh:Geography. Anthropology. Recreation, Wind direction, Geodesy, Swell, lcsh:G, Surface wave, [SDU]Sciences of the Universe [physics], symbols, Doppler effect, Geology
Abstract: Surface currents are poorly known over most of the world's oceans. Satellite-borne Doppler wave and current scatterometers (DWaCSs) are among the proposed techniques to fill this observation gap. The Sea surface KInematics Multiscale (SKIM) proposal is the first satellite concept built on a DWaCS design at near-nadir angles and was demonstrated to be technically feasible as part of the European Space Agency Earth Explorer program. This article describes preliminary results from a field experiment performed in November 2018 off the French Atlantic coast, with sea states representative of the open ocean and a well-known tide-dominated current regime, as part of the detailed design and feasibility studies for SKIM. This experiment comprised airborne measurements performed using Ku-band and Ka-band Doppler radars looking at the sea surface at near-nadir incidence in a real-aperture mode, i.e., in a geometry and mode similar to that of SKIM, as well as an extensive set of in situ instruments. The Ku-band Radar for Observation of Surfaces (KuROS) airborne radar provided simultaneous measurements of the radar backscatter and Doppler velocity in a side-looking configuration, with a horizontal resolution of about 5 to 10 m along the line of sight and integrated in the perpendicular direction over the real-aperture 3 dB footprint diameter (about 580 m). The Ka-band RADar for Ocean Current (KaRADOC) system, also operating in the side-looking configuration, had a much narrower beam, with a circular footprint only 45 m in diameter. Results are reported for two days with contrasting conditions, a strong breeze on 22 November 2018 (wind speed 11.5 m s−1, Hs 2.6 m) and gentle breeze on 24 November 2018 (wind speed 5.5 m s−1, Hs 1.7 m). The measured line-of-sight velocity signal is analyzed to separate a non-geophysical contribution linked to the aircraft velocity, a geophysical contribution due to the intrinsic motion of surface waves and the desired surface current contribution. The surface wave contribution is found to be well predicted by Kirchhoff scattering theory using as input parameters in situ measurements of the directional spectrum of long waves, complemented by the short wave spectrum of Elfouhaily et al. (1997). It is found to be closely aligned with the wind direction, with small corrections due to the presence of swell. Its norm is found to be weakly variable with wind speed and sea state, quite stable and close to C0=2.0ms-1 at the Ka band, and more variable and close to C0=2.4ms-1 at the Ku band. These values are 10 %–20 % smaller than previous theoretical estimates. The directional spread of the short gravity waves is found to have a marked influence on this surface wave contribution. Overall, the results of this study support the feasibility of near-nadir radar Doppler remote sensing of the ocean total surface current velocity (TSCV).
Published: 2020
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18. Modelled mid‐trophic pelagic prey fields improve understanding of marine predator foraging behaviour

Author: Mark A. Hindell, Patrick Lehodey, Stuart Corney, Clive R. McMahon, Christophe Guinet, David B. Green, Sophie Bestley, Rowan Trebilco, Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institute for Marine and Antarctic Studies [Horbat] (IMAS), and University of Tasmania [Hobart, Australia] (UTAS)
Subjects: 0106 biological sciences, predators prey interaction, Foraging, 010603 evolutionary biology, 01 natural sciences, Predation, southern elephant seal, Abundance (ecology), Marine ecosystem, 14. Life underwater, Ecology, Evolution, Behavior and Systematics, Trophic level, Biomass (ecology), biology, Ecology, 010604 marine biology & hydrobiology, micronekton, Pelagic zone, ecosystem modelling, 15. Life on land, biology.organism_classification, kerguelen plateau, Southern elephant seal, 13. Climate action, [SDE]Environmental Sciences, Environmental science, Southern Indian Ocean
Abstract: International audience; Biophysical interactions are influential in determining the scale of key ecological processes within marine ecosystems. For oceanic predators, this means foraging behaviour is influenced by processes shaping the distribution of prey. However, oceanic prey is difficult to observe and its abundance and distribution is regionally generalised. We use a spatiotemporally resolved simulation model to describe mid‐trophic prey distribution within the Southern Ocean and demonstrate insights that this modelled prey field provides into the foraging behaviour of a widely distributed marine predator, the southern elephant seal.From a five‐year simulation of prey biomass, we computed climatologies of mean prey biomass (average prey conditions) and prey biomass variability (meso‐scale variability). We also compiled spatially gridded metrics of seal density and diving behaviour from 13 yr of tracking data. We statistically modelled these metrics as non‐linear functions of prey biomass (both mean and variability) and used these to predict seal distribution and behaviour. Our predictions were consistent with observations (R2adj = 0.23), indicating that seals aggregate in regions of high mesoscale activity where eddies concentrate prey. Here, seals dived deeper (R2marg = 0.12, R2cond = 0.51) and spent less time hunting (R2marg = 0.05, R2cond = 0.56), likely targeting deep but profitable prey patches. Seals generally avoided areas of low eddy activity where prey was likely dispersed. Most seals foraged south of the Subantarctic Front, despite north of the front exhibiting consistently high simulated prey biomasses. This likely reflects seal prey or habitat preferences, but also emphasises the importance of mesoscale prey biomass variability relative to regionally high mean biomass. This work demonstrates the value of coupling mechanistic representations of prey biomass with predator observations to provide insight into how biophysical processes combine to shape species distributions. This will be increasingly important for the robust prediction of species’ responses to rapid system change.
Published: 2020
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19. Influence of oceanic conditions in the energy transfer efficiency estimation of a micronekton model

Author: A. Delpech, A. Conchon, O. Titaud, P. Lehodey, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Mercator Océan, Société Civile CNRS Ifremer IRD Météo-France SHOM, and Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)
Subjects: 0106 biological sciences, 010504 meteorology & atmospheric sciences, Mesopelagic zone, lcsh:Life, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Atmospheric sciences, 01 natural sciences, Deep sea, lcsh:QH540-549.5, Marine ecosystem, 14. Life underwater, Diel vertical migration, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, Earth-Surface Processes, 010604 marine biology & hydrobiology, Ocean current, lcsh:QE1-996.5, Biological pump, Sampling (statistics), Pelagic zone, lcsh:Geology, lcsh:QH501-531, [SDU]Sciences of the Universe [physics], Environmental science, lcsh:Ecology
Abstract: Micronekton – small marine pelagic organisms mostly in the size range 1–10 cm – is a key component of the ocean ecosystem, as it constitutes the main source of forage for all larger predators. Moreover, the mesopelagic component of micronekton that undergoes Diel Vertical Migration (DVM) likely plays a key role in the transfer and storage of CO2 in the deep ocean: the so-called ‘biological pump’ mechanism. SEAPODYM-MTL is a spatially explicit dynamical model of micronekton. It simulates six functional groups of migrant and non-migrant micronekton, in the epipelagic and mesopelagic layers. Coefficients of energy transfer efficiency between primary production and each group are unknown. But they are essential as they control the predicted biomass. Since these coefficients are not directly measurable, a data assimilation method is used to estimate them. In this study, Observing System Simulation Experiments (OSSE) in the framework of twin experiments are used to test various observation networks at a global scale regarding energy transfer coefficients estimation. Observational networks show a variety of performances. It appears that environmental conditions are crucial to determine network efficiency. According to our study, ideal sampling areas are warm, non-dynamic and productive waters like the eastern side of tropical Oceans. These regions are found to reduce the error of estimated coefficients by 20 % compared to cold and dynamic sampling regions. The results are discussed in term of interactions between physical and biological processes.
Published: 2020
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20. JOINT CALIBRATION AND MAPPING OF SATELLITE ALTIMETRY DATA USING TRAINABLE VARIATIONAL MODELS

Author: Febvre, Quentin, Fablet, Ronan, Sommer, Julien Le, Ubelmann, Clément, Febvre, Quentin, Bridging geohysics and MachinE Learning for the modeling, simulation and reconstruction of Ocean DYnamics - - MeLODy2019 - ANR-19-CE46-0011 - AAPG2019 - VALID, LabSTICC (UMR CNRS 6285), LabSTICC, Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC), Institut Mines-Télécom [Paris] (IMT)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), OceanNext, Département Mathematical and Electrical Engineering (IMT Atlantique - MEE), IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Equipe Observations Signal & Environnement (Lab-STICC_OSE), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT), Laboratoire des Écoulements Géophysiques et Industriels [Grenoble] (LEGI), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), This work was supported by CNES, CLS, ANR Melody Oceanix, IDRI., ANR-19-CE46-0011,MeLODy,Bridging geohysics and MachinE Learning for the modeling, simulation and reconstruction of Ocean DYnamics(2019), and École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique)
Subjects: FOS: Computer and information sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Computer Science - Machine Learning, FOS: Physical sciences, deep learning, [INFO.INFO-LG] Computer Science [cs]/Machine Learning [cs.LG], calibration, satellite altimetry, Machine Learning (cs.LG), Physics - Atmospheric and Oceanic Physics, [INFO.INFO-LG]Computer Science [cs]/Machine Learning [cs.LG], Atmospheric and Oceanic Physics (physics.ao-ph), Variational model, data assimilation, [SPI.SIGNAL] Engineering Sciences [physics]/Signal and Image processing
Abstract: Satellite radar altimeters are a key source of observation of ocean surface dynamics. However, current sensor technology and mapping techniques do not yet allow to systematically resolve scales smaller than 100km. With their new sensors, upcoming wide-swath altimeter missions such as SWOT should help resolve finer scales. Current mapping techniques rely on the quality of the input data, which is why the raw data go through multiple preprocessing stages before being used. Those calibration stages are improved and refined over many years and represent a challenge when a new type of sensor start acquiring data. Here we show how a data-driven variational data assimilation framework could be used to jointly learn a calibration operator and an interpolator from non-calibrated data . The proposed framework significantly outperforms the operational state-of-the-art mapping pipeline and truly benefits from wide-swath data to resolve finer scales on the global map as well as in the SWOT sensor geometry.
Published: 2022

21. Semantic Segmentation of Metoceanic Processes Using SAR Observations and Deep Learning

Author: Colin, Aurélien, Fablet, Ronan, Tandeo, Pierre, Husson, Romain, Peureux, Charles, Longépé, Nicolas, Mouche, Alexis, Département Mathematical and Electrical Engineering (IMT Atlantique - MEE), IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Equipe Observations Signal & Environnement (Lab-STICC_OSE), Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT), Collecte Localisation Satellites (CLS), Océan Dynamique Observations Analyse (ODYSSEY), Université de Bretagne Occidentale - UFR Sciences et Techniques (UBO UFR ST), Université de Brest (UBO)-Université de Brest (UBO)-Université de Rennes (UR)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-IMT Atlantique (IMT Atlantique), Agence Spatiale Européenne = European Space Agency (ESA), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Laboratoire d'Océanographie Physique et Spatiale (LOPS), and Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [INFO.INFO-LG]Computer Science [cs]/Machine Learning [cs.LG], [SDE.IE]Environmental Sciences/Environmental Engineering, weakly-supervised learning, segmentation, metocean, deep learning, Sentinel-1, supervised learning, [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing, SAR
Abstract: International audience; Through the Synthetic Aperture Radar (SAR) embarked on the satellites Sentinel-1A and Sentinel-1B of the Copernicus program, a large quantity of observations is routinely acquired over the oceans. A wide range of features from both oceanic (e.g., biological slicks, icebergs, etc.) and meteorologic origin (e.g., rain cells, wind streaks, etc.) are distinguishable on these acquisitions. This paper studies the semantic segmentation of ten metoceanic processes either in the context of a large quantity of image-level groundtruths (i.e., weakly-supervised framework) or of scarce pixel-level groundtruths (i.e., fully-supervised framework). Our main result is that a fully-supervised model outperforms any tested weakly-supervised algorithm. Adding more segmentation examples in the training set would further increase the precision of the predictions. Trained on 20 × 20 km imagettes acquired from the WV acquisition mode of the Sentinel-1 mission, the model is shown to generalize, under some assumptions, to wide-swath SAR data, which further extents its application domain to coastal areas
Published: 2022
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22. META3.1exp: a new global mesoscale eddy trajectory atlas derived from altimetry

Author: Cori Pegliasco, Antoine Delepoulle, Evan Mason, Rosemary Morrow, Yannice Faugère, Gérald Dibarboure, Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Centre National d’Études Spatiales [Paris] (CNES)
Subjects: [SDU]Sciences of the Universe [physics], General Earth and Planetary Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Abstract: This paper presents the new global Mesoscale Eddy Trajectory Atlases (META3.1exp DT all-satellites, https://doi.org/10.24400/527896/a01-2021.001, Pegliasco et al., 2021a; and META3.1exp DT two-satellites, https://doi.org/10.24400/527896/a01-2021.002, Pegliasco et al., 2021b), composed of eddy identifications and trajectories produced with altimetric maps. The detection method used is inherited from the py-eddy-tracker (PET) algorithm developed by Mason et al. (2014), and is optimized to efficiently manage large datasets, and thus long time series. These products are an improvement on the earlier META2.0 product, which was produced by SSALTO/DUACS and distributed by AVISO+ (https://aviso.altimetry.fr, last access: 8 March 2022) with support from CNES, in collaboration with Oregon State University and support from NASA, and based on the Chelton et al. (2011) code. META3.1exp provides supplementary eddy information, such as eddy shapes, eddy edges, maximum speed contours, and mean eddy speed profiles from the center to the periphery. The tracking algorithm is based on overlapping contours, includes virtual observations, and acts as a filter with respect to the shortest trajectories. The absolute dynamic topography (ADT) field is now used for eddy detection, instead of the previous sea level anomaly (SLA) maps, in order to better represent the dynamics in the more energetic oceanic regions and in the vicinity of coasts and islands. To evaluate the impact of the changes from META2.0 to META3.1exp, a comparison methodology has been applied. The similarity coefficient (SC) is based on the ratio of the eddy overlaps to their cumulative area, and allows for extensive comparison of the different datasets in terms of geographic distribution, statistics on the main physical characteristics, changes in the lifetimes of the trajectories, etc. After evaluating the impact of each change separately, we conclude that the major differences between META3.1exp and META2.0 are due to the change in the detection algorithm. META3.1exp contains smaller eddies and trajectories lasting at least 10 d; these were not available in the META2.0 product. Nevertheless, 55 % of the structures in META2.0 are similar to META3.1exp, thereby ensuring continuity between the two products and their physical characteristics. Geographically, the eddy distributions differ mainly in the strong current regions, where the mean dynamic topography (MDT) gradients are sharp. The additional information on the eddy contours allows for more accurate collocation of mesoscale structures with data from other sources, and so META3.1exp is recommended for multi-disciplinary application.
Published: 2022
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23. Rétrodiffusion radar par une surface de mer polluée : Modélisation 3D et comparaison avec des mesures

Author: Pinel, Nicolas, Bourlier, Christophe, Sergievskaya, Irina, Longépé, Nicolas, Hajduch, Guillaume, Charlier, Sandrine, Institut Catholique d'Arts et Métiers (ICAM), Institut d'Électronique et des Technologies du numéRique (IETR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), Russian Academy of Sciences [Moscow] (RAS), ESA Centre for Earth Observation (ESRIN), Agence Spatiale Européenne = European Space Agency (ESA), Collecte Localisation Satellites (CLS), and ONERA
Subjects: [SPI.OTHER]Engineering Sciences [physics]/Other, pollutions par des hydro- carbures, [SPI]Engineering Sciences [physics], [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, Diffusion électro- magnétique par la surface de la mer, Surface Equivalente Radar, [SPI] Engineering Sciences [physics], [SPI.OTHER] Engineering Sciences [physics]/Other, [SPI.ELEC] Engineering Sciences [physics]/Electromagnetism, [SPI.TRON] Engineering Sciences [physics]/Electronics, [SPI.TRON]Engineering Sciences [physics]/Electronics
Abstract: National audience; Ce papier présente des modélisations de rétro-diffusion radar par des mers recouvertes de pollutionsd’hydrocarbures. Elle part d’une modélisation fine du com-portement hydrodynamique d’une surface de mer polluée(MLB, Model of Local Balance). Le problème double interfaceair/pétrole/mer est traité soit par une approche de type couchemince (TL, thin-layer), soit par l’approche classique qui consisteà négliger la couche de pétrole dans la modélisation électro-magnétique. Différents modèles électromagnétiques classiques, enparticulier le modèle SSA du premier ordre, sont alors testés avecsuccès, par comparaison avec des mesures satellitaires.
Published: 2022

24. Subpolar Southern Ocean Seasonal Variability of the Geostrophic Circulation From Multi-Mission Satellite Altimetry

Author: Matthis Auger, Jean‐Baptiste Sallée, Pierre Prandi, Alberto C. Naveira Garabato, Processus et interactions de fine échelle océanique (PROTEO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Ocean and Earth Science [Southampton], and University of Southampton-National Oceanography Centre (NOC)
Subjects: Geophysics, Space and Planetary Science, Geochemistry and Petrology, [SDU]Sciences of the Universe [physics], Earth and Planetary Sciences (miscellaneous), seasonal cycle, ocean circulation, Oceanography, Southern Ocean, satellite altimetry, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography
Abstract: International audience; A novel multi-satellite product is used to shed light on the sea surface height seasonal cycle and associated geostrophic circulation in the subpolar Southern Ocean. We find three main modes of variability governing the Sea Level Anomaly seasonal cycle, all of them primarily governed by wind forcing. The main mode of seasonal variability is associated with the seasonality of the main subpolar gyres governed by large-scale wind stress curl, qualitatively consistent with Sverdrup dynamics. The second seasonal mode is related to the Antarctic Slope Current (ASC), governed by the coastal easterlies, with a rapid circumpolar propagation of anomalous sea-level along the continental slope that is dynamically consistent with the so-called Southern Mode. The first two modes induce an acceleration of the gyres and the ASC in winter. The third seasonal mode appears to be driven by sea ice-modulated surface stress and induces an offshore extension of the ASC from autumn to winter.
Published: 2022
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25. Co-Cross-Polarization Coherence Over the Sea Surface From Sentinel-1 SAR Data: Perspectives for Mission Calibration and Wind Field Retrieval

Author: Laurent Ferro-Famil, Nicolas Longépé, Romain Husson, Alexis Mouche, Collecte Localisation Satellites (CLS), Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut d'Électronique et des Technologies du numéRique (IETR), Université de Nantes (UN)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), European Space Agency ESA through the Scientific Exploitation of Operational Missions SEOM S1 for Ocean Studies Project, Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), and Nantes Université (NU)-Université de Rennes 1 (UR1)
Subjects: Synthetic aperture radar, 010504 meteorology & atmospheric sciences, 0211 other engineering and technologies, Polarimetry, 02 engineering and technology, Wind, single look complex (SLC), 01 natural sciences, Wind speed, law.invention, [SPI]Engineering Sciences [physics], wind field retrieval, law, Sea measurements, Coherence (signal processing), Electrical and Electronic Engineering, Radar, Physics::Atmospheric and Oceanic Physics, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, Remote sensing, Sea surface, Spaceborne radar, synthetic aperture radar (SAR), Numerical weather prediction, Relative wind, Azimuth, polarimetric calibration (PolCAL), General Earth and Planetary Sciences, Sentinel-1 (S-1), Geology, Dual-polarization
Abstract: International audience; Spaceborne synthetic aperture radar (SAR) has been used for years to estimate high-resolution surface wind field from the ocean surface backscattered signal. Current SAR platforms have one single fixed antenna, and traditional inversion/retrieval schemes rely on one copolarized channel, leading to an unconstrained optimization problem for providing independent estimates of wind speed and direction. For routine application, this is generally solved with a priori information from the numerical weather prediction (NWP) model, inducing severe limitations for rapidly evolving meteorological systems where discrepancies can be significant between model and measurements. In this study, we investigate the benefit of having two simultaneous acquisitions with phase-preserving information in copolarization and cross polarization provided by Sentinel-1 (S-1). A comprehensive analysis of the co-cross-polarization coherence (CCPC) is performed to adequately estimate and calibrate CCPC values from S-1 interferometric wide (IW) mode images acquired over the ocean. A new polarimetric calibration (PolCAL) methodology based on least-squares (LS) criterion and direct matrix inversion is proposed yielding crosstalk estimates. We document CCPC odd symmetry with respect to relative wind direction for light to medium wind speeds (up to 14 m/s) and incidence angle from 30and#x00B0; to 45and#x00B0;. The azimuthal modulation is found to increase with both wind speed and incidence angle. An analytical model C-band polarimetric geophysical model function (CPGMF) is provided. The synergy of the CCPC with other radar parameters, such as backscattering coefficients or Doppler, to further constrain the inversion scheme is assessed, opening new perspectives for SAR-based wind field retrieval independent of any NWP model information. IEEE
Published: 2022
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26. Background stratification impacts on internal tide generation and abyssal propagation in the western equatorial Atlantic and the Bay of Biscay

Author: Florent Lyard, Michel Tchilibou, Loren Carrere, Simon Barbot, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Pycnocline, 010504 meteorology & atmospheric sciences, 010505 oceanography, Internal tide, Ocean current, Elevation, Mesoscale meteorology, Stratification (water), 01 natural sciences, Abyssal zone, Environmental sciences, Oceanography, 13. Climate action, Geography. Anthropology. Recreation, GE1-350, 14. Life underwater, Bay, Geology, 0105 earth and related environmental sciences
Abstract: The forthcoming SWOT altimetric missions aim to resolve the mesoscale with an unprecedented spatial resolution and swath. However, high-frequency processes, such as tides, are undersampled in time and aliased onto lower frequencies, so they need to be corrected properly. Unlike barotropic tides, internal tides (ITs) are not completely stationary and have significant temporal variability due to their interactions with the ocean circulation and the stratification variability. Stratification changes impact both the generation and the propagation of ITs. The present study proposes a methodology to quantify the impacts of background stratification using a clustering method for the classification of a broad range of stratification and idealized modeling of ITs in the frequency domain. The methodology is successfully tested in the western equatorial Atlantic and in the Bay of Biscay. For the western equatorial Atlantic, a single pycnocline is observed and only the two first vertical modes of ITs have significant amplitudes. With no variation in the stratification intensity, the variation in the depth of this single pycnocline linearly impacts the elevation amplitude, energy fluxes and surface wavelength of the two modes. In the Bay of Biscay, there is a permanent deep pycnocline and secondary seasonal pycnoclines near the surface. No proxy have been found to describe the changes in ITs, so a seasonal climatology is explored. The seasonality of the stratification strongly affects the elevation amplitudes as well as the energy fluxes of modes 1, 2 and 3. The distribution of the modes vary with the background stratification, changing the horizontal scales of the ITs.
Published: 2021
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27. Animal Borne Ocean Sensors – AniBOS – An Essential Component of the Global Ocean Observing System

Author: Clive R. McMahon, Fabien Roquet, Sophie Baudel, Mathieu Belbeoch, Sophie Bestley, Clint Blight, Lars Boehme, Fiona Carse, Daniel P. Costa, Michael A. Fedak, Christophe Guinet, Robert Harcourt, Emma Heslop, Mark A. Hindell, Xavier Hoenner, Kim Holland, Mellinda Holland, Fabrice R. A. Jaine, Tiphaine Jeanniard du Dot, Ian Jonsen, Theresa R. Keates, Kit M. Kovacs, Sara Labrousse, Philip Lovell, Christian Lydersen, David March, Matthew Mazloff, Megan K. McKinzie, Mônica M. C. Muelbert, Kevin O’Brien, Lachlan Phillips, Esther Portela, Jonathan Pye, Stephen Rintoul, Katsufumi Sato, Ana M. M. Sequeira, Samantha E. Simmons, Vardis M. Tsontos, Victor Turpin, Esmee van Wijk, Danny Vo, Mia Wege, Frederick Gilbert Whoriskey, Kenady Wilson, Bill Woodward, NERC, University of St Andrews. School of Biology, University of St Andrews. Scottish Oceans Institute, University of St Andrews. Sea Mammal Research Unit, University of St Andrews. Marine Alliance for Science & Technology Scotland, IMOS Animal Tagging [New South Wales, Australia], Sydney Institute of Marine Science, Department of Marine Sciences [Gothenburg], University of Gothenburg (GU), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), OceanOPS, Institute for Marine and Antarctic Studies [Hobart] (IMAS), University of Tasmania [Hobart, Australia] (UTAS), Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Processus et interactions de fine échelle océanique (PROTEO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)
Subjects: 010504 meteorology & atmospheric sciences, Science, QH301 Biology, T-NDAS, Temperature salinity diagrams, Climate change, Ocean Engineering, QH1-199.5, Aquatic Science, Physical oceanography, Oceanography, animal behavior, 01 natural sciences, marine animals, QH301, 03 medical and health sciences, SDG 13 - Climate Action, Sea ice, SDG 14 - Life Below Water, 14. Life underwater, Essential Ocean Variables (EOVs), 030304 developmental biology, 0105 earth and related environmental sciences, Water Science and Technology, GC, 0303 health sciences, Global and Planetary Change, geography, geography.geographical_feature_category, Data stream mining, General. Including nature conservation, geographical distribution, physical oceanography, climate change, 13. Climate action, Climatology, [SDE]Environmental Sciences, Sustainability, Environmental science, GC Oceanography, Satellite, Hydrography
Abstract: Funding and support for the November 2019 Network Development Workshop was provided by the Integrated Marine Observing System (IMOS) and the Australia Research Council’s Special Research Initiative for Antarctic Gateway Partnership (SR140300001) through the University of Tasmania’s Institute of Marine and Antarctic Studies. IMOS is a national collaborative research infrastructure, supported by the Australian Government and operated by a consortium of institutions as an unincorporated joint venture, with the University of Tasmania as Lead Agent. This research contributes to the Australian Research Council Discovery Project DP180101667 and DP210103091. SBe was supported under the Australian Research Council DECRA DE180100828. IJ was supported by Macquarie University’s co-Funded Fellowship Program with external partners: Office of Naval Research (N00014-18-1-2405); the Integrated Marine Observing System – Animal Tracking Facility; the Ocean Tracking Network; Taronga Conservation Society; Birds Canada; and Innovasea/Vemco. AS was supported by a 2020 Pew Fellowship in Marine Conservation. DM was supported by the European Union’s Horizon 2020 Research and Innovation Program under the Marie Skłodowska-Curie grant agreement (No. 794938). Marine animals equipped with biological and physical electronic sensors have produced long-term data streams on key marine environmental variables, hydrography, animal behavior and ecology. These data are an essential component of the Global Ocean Observing System (GOOS). The Animal Borne Ocean Sensors (AniBOS) network aims to coordinate the long-term collection and delivery of marine data streams, providing a complementary capability to other GOOS networks that monitor Essential Ocean Variables (EOVs), essential climate variables (ECVs) and essential biodiversity variables (EBVs). AniBOS augments observations of temperature and salinity within the upper ocean, in areas that are under-sampled, providing information that is urgently needed for an improved understanding of climate and ocean variability and for forecasting. Additionally, measurements of chlorophyll fluorescence and dissolved oxygen concentrations are emerging. The observations AniBOS provides are used widely across the research, modeling and operational oceanographic communities. High latitude, shallow coastal shelves and tropical seas have historically been sampled poorly with traditional observing platforms for many reasons including sea ice presence, limited satellite coverage and logistical costs. Animal-borne sensors are helping to fill that gap by collecting and transmitting in near real time an average of 500 temperature-salinity-depth profiles per animal annually and, when instruments are recovered (∼30% of instruments deployed annually, n = 103 ± 34), up to 1,000 profiles per month in these regions. Increased observations from under-sampled regions greatly improve the accuracy and confidence in estimates of ocean state and improve studies of climate variability by delivering data that refine climate prediction estimates at regional and global scales. The GOOS Observations Coordination Group (OCG) reviews, advises on and coordinates activities across the global ocean observing networks to strengthen the effective implementation of the system. AniBOS was formally recognized in 2020 as a GOOS network. This improves our ability to observe the ocean’s structure and animals that live in them more comprehensively, concomitantly improving our understanding of global ocean and climate processes for societal benefit consistent with the UN Sustainability Goals 13 and 14: Climate and Life below Water. Working within the GOOS OCG framework ensures that AniBOS is an essential component of an integrated Global Ocean Observing System. Publisher PDF
Published: 2021
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28. Double-scale di usive wave equation dedicated to spatial rivers observations

Author: Malou, Thibault, Monnier, Jerome, Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA), Institut de Mathématiques de Toulouse UMR5219 (IMT), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Collecte Localisation Satellites (CLS), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT), Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Université Fédérale Toulouse Midi-Pyrénées, Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), and Institut National des Sciences Appliquées (INSA)-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées (INSA)-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3)
Subjects: [PHYS.PHYS.PHYS-COMP-PH]Physics [physics]/Physics [physics]/Computational Physics [physics.comp-ph], [MATH.MATH-MP]Mathematics [math]/Mathematical Physics [math-ph], river flow modeling, satellite observations, [MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP], Diffusive wave equations, two-scale asymptotic derivation, double-scale asymptotic derivation, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, quantification of model terms
Abstract: In river flow modeling, the diffusive wave equation can be an interesting approximation of the Saint-Venant equations because it is simpler and still allows a rich modeling. Moreover, the computed variable is the water surface elevation which can be directly measured, unlike the discharge. This study introduces a space-time double scale that considers both the physical scale (the small scale) and the observations scale (the large scale). At the physical scale, the gradually varied assumption holds and the spatio-temporal variations of the river width are negligible. However, this is often not true at the observations scale. Then, an enriched di usive wave equation in agreement with the observations scale, called the observations-scale di usive wave equation, is rigorously derived. The latter takes into account the spatio-temporal variations of the width through additional terms. This new equation and the classical di usive wave equation are numerically compared with each other, and with the Saint-Venant system taken as reference. This new di usive wave equation provides better estimates of the slope of the free surface and of the discharge than the classical one. Finally, the importance of the additional terms specific to the observations-scale di usive wave is quantified using a sparse identification method in a dictionary of di erential model terms. This original approach highlights that a newly introduced term is one of the dominant terms.
Published: 2021

29. Covariance kernels investigation from diffusive wave equations for data assimilation in hydrology

Author: T Malou, J Monnier, Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA), Institut de Mathématiques de Toulouse UMR5219 (IMT), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Collecte Localisation Satellites (CLS), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT), Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)
Subjects: covariance modeling, Applied Mathematics, background error, river hydraulics, Computer Science Applications, Theoretical Computer Science, physically-derived covariance estimates, Green's kernel, Signal Processing, [MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP], Variational data assimilation, [MATH.MATH-OC]Mathematics [math]/Optimization and Control [math.OC], diffusive wave equations, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, Mathematical Physics, [MATH.MATH-NA]Mathematics [math]/Numerical Analysis [math.NA]
Abstract: In data assimilation (DA), the estimation of the background error covariance operator is a classical and still open topic. However, this operator is often modeled using empirical information. In order to exploit at best the potential of the knowledge of the physics, the present study proposes a method to derive covariance operators from the underlying equations. In addition, Green’s kernels can be used to model covariance operators and are naturally linked to them. Therefore, Green’s kernels of equations representing physics can provide physically-derived estimates of the background error covariance operator, and also physically-consistent parameters. In this context, the present covariance operators are used in a variational DA (VDA) process of altimetric data to infer bathymetry in the Saint-Venant equations. In order to investigate these new physically-derived covariance operators, the associated VDA results are compared to the VDA results using classical operators with physically-consistent and arbitrary parameters. The physically-derived operators and physically-consistent exponential operator provide better accuracy and faster convergence than empirical operators, especially during the first iterations of the VDA optimization process.
Published: 2021

30. High-Sustained Concentrations of Organisms at Very low Oxygen Concentration Indicated by Acoustic Profiles in the Oxygen Deficit Region Off Peru

Author: Carlos Conejero, Javier Sellanes, Carlos Gaymer, Marilaure Grégoire, Daniel J. Conley, Ariadna Mechó, Ivonne Montes, Lisa A. Levin, Anja van der Plas, Anja Engel, Aurélien Paulmier, Renato Salvatteci, Alberto Lorenzo, Dimitri Gutiérrez, Gérard Eldin, Carolina Parada, Naqvi Swa, Jacob Carstensen, Dante Espinoza-Morriberón, Jaques Grelet, Anne Gro Vea Salvanes, Boris Dewitte, Jing Zhang, Denise L. Breitburg, Abdelfettah Sifeddine, J. Sudre, Michael R. Roman, José Martín Hernández-Ayón, Kobi Mosquera-Vásquez, Georgina Flores, Lander Merma, José Ochoa, Véronique Garçon, Zy Zhu, Helmut Maske, Michelle Graco, Luis Bravo, Arturo Aguirre-Velarde, Jorge Cardich, Grant C. Pitcher, Eric Machu, Oscar Vergara, Moriaki Yasuhara, Huai-Hsuan May Huang, María Elena Jacinto, Sonia Sánchez, Abdoul Wahab Tall, Raleigh R. Hood, Praxedes Muñoz, Nancy N. Rabalais, Kenneth A. Rose, Kirsten Isensee, Marcel Ramos, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Departamento de Oceanografia Fisica CICESE [Mexico], Centro de Investigacion Cientifica y de Education Superior de Ensenada [Mexico] (CICESE), Departamento de Biología Marina [Coquimbo], Universidad Católica del Norte [Antofagasta], Centro de Estudios Avanzados en Zonas Aridas (CEAZA), Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS), Instrumentation, Moyens analytiques, Observatoires en Géophysique et Océanographie (IMAGO), Instituto Geofísico del Perú (IGP), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Centro de Investigacion Científica y de Educacion Superior de Ensenada, Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)
Subjects: 010504 meteorology & atmospheric sciences, Backscatter, Eastern Tropical South Pacific, Mesopelagic zone, Science, [SDE.MCG]Environmental Sciences/Global Changes, Analytical chemistry, chemistry.chemical_element, Ocean Engineering, Aquatic Science, QH1-199.5, Oceanography, 01 natural sciences, Oxygen, 03 medical and health sciences, Water column, Acoustic Doppler current profiler, oxygen minimum zone (OMZ), [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 030304 developmental biology, 0105 earth and related environmental sciences, Water Science and Technology, 0303 health sciences, Global and Planetary Change, microaerobic zooplankton, Low oxygen, Chemistry, General. Including nature conservation, geographical distribution, biomass below OMZ, 15. Life on land, lowered ADCP, Volume (thermodynamics), Limiting oxygen concentration
Abstract: The oxygen deficient mesopelagic layer (ODL) off Peru has concentrations below 5 μmol O2 kg–1 and is delimited by a shallow upper oxycline with strong vertical gradient and a more gradual lower oxycline (lOx). Some regions show a narrow band of slightly increased oxygen concentrations within the ODL, an intermediate oxygen layer (iO2). CTD, oxygen and lowered Acoustic Doppler Current Profiler (LADCP, 300 kHz) profiles were taken on the shelf edge and outside down to mostly 2000 m. We evaluate here the acoustic volume backscatter strength of the LADCP signal representing organisms of about 5 mm size. Dominant features of the backscatter profiles were a minimum backscatter strength within the ODL, and just below the lOx a marked backscatter increase reaching a maximum at less than 3.0 μmol O2 kg–1. Below this maximum, the acoustic backscatter strength gradually decreased down to 1000 m below the lOx. The backscatter strength also increased at the iO2 in parallel to the oxygen concentration perturbations marking the iO2. These stable backscatter features were independent of the time of day and the organisms represented by the backscatter had to be adapted to live in this microaerobic environment. During daylight, these stable structures were overlapped by migrating backscatter peaks. Outstanding features of the stable backscatter were that at very low oxygen concentrations, the volume backscatter was linearly related to the oxygen concentration, reaching half peak maximum at less than 2.0 μmol O2 kg–1 below the lOx, and the depth-integrated backscatter of the peak below the lOx was higher than the integral above the Ox. Both features suggest that sufficient organic material produced at the surface reaches to below the ODL to sustain the major fraction of the volume backscatter-producing organisms in the water column. These organisms are adapted to the microaerobic environment so they can position themselves close to the lower oxycline to take advantage of the organic particles sinking out of the ODL.
Published: 2021
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31. Radar altimeter waveform simulations in Antarctica with the Snow Microwave Radiative Transfer Model (SMRT)

Author: Larue, Fanny, Picard, Ghislain, Aublanc, Jérémie, Arnaud, Laurent, Robledano-Perez, Alvaro, Le Meur, Emmanuel, Favier, Vincent, Jourdain, Bruno, Savarino, Joel, Thibaut, Pierre, Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Collecte Localisation Satellites (CLS), and ANR-16-CE01-0011,EAIIST,Projet International d'exploration de la calotte polaire de l'Antarctique de l'Est(2016)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, remote sensing, waveform, Antarctic ice sheet, field measurements, modeling, SMRT, radar altimetry
Abstract: International audience; Radar altimeters are important tools to monitor the volume of the ice sheets. The penetration of radar waves in the snowpack is a major source of uncertainty to retrieve surface elevation. To correct this effect, a better understanding of the sensitivity of the radar waveforms to snow properties is needed. Here, we present an extension of the Snow Model Radiative Transfer (SMRT) to compute radar waveforms and conduct a series of simulations on the Antarctic ice sheet. SMRT is driven by snow and surface roughness properties measured over a large latitudinal range during two field campaigns on the Antarctic Plateau. These measurements show that the snowpack is rougher, denser, less stratified, warmer, and has smaller snow grains near the coast than on the central Plateau. These simulations are compared to satellite observations in the Ka, Ku, and S bands. SMRT reproduces the observed waveforms well. For all sites and all sensors, the main contribution comes from the surface echo. The echo from snow grains (volume scattering) represents up to 40% of the amplitude of the total waveform power in the Ka band, and less at the lower frequencies. The highest amplitude is observed on the central Plateau due to the combination
Published: 2021
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32. Towards a better characterisation of deep-diving whales’ distributions by using prey distribution model outputs?

Author: Auriane Virgili, Laura Hedon, Matthieu Authier, Beatriz Calmettes, Diane Claridge, Tim Cole, Peter Corkeron, Ghislain Dorémus, Charlotte Dunn, Tim E Dunn, Sophie Laran, Patrick Lehodey, Mark Lewis, Maite Louzao, Laura Mannocci, José Martínez-Cedeira, Pascal Monestiez, Debra Palka, Emeline Pettex, Jason J Roberts, Leire Ruiz, Camilo Saavedra, M Begoña Santos, Olivier Van Canneyt, José Antonio Vázquez Bonales, Vincent Ridoux, Observatoire PELAGIS UMS 3462 (PELAGIS), LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS)-Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Observatoire pour la Conservation de la Mégafaune Marine (PELAGIS), LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), LEB Aquitaine Transfert-ADERA, CLS Space Oceanography Division, Collecte Localisation Satellites (CLS), Bahamas Marine Mammal Research Organisation, NOAA Northeast Fisheries Science Center, National Oceanic and Atmospheric Administration (NOAA), Joint Nature Conservation Committee, Marine Habitats Team, Basque Research and Technology Alliance (BRTA), MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), CEMMA, Coordinadora para o Estudio dos Mamiferos Marinos, Biostatistique et Processus Spatiaux (BioSP), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), ADERA, Cellule Cohabys (Cohabys), Duke University [Durham], AMBAR Elkartea Organisation [Bizkaia, Spain], Instituto Español de Oceanografía (IEO), Málaga., and Alnilam Research and Conservation [Madrid, Spain]
Subjects: Ecological Metrics, Science, Beaked Whales, Diving, Oceans and Seas, Predation, Marine and Aquatic Sciences, Marine Biology, Oceanography, Zooplankton, Bodies of water, Oceans, Animals, Biomass, Marine Mammals, Atlantic Ocean, Ecosystem, Mammals, Sperm Whales, Ecology, Sperm Whale, Ecology and Environmental Sciences, Organisms, Whales, Biology and Life Sciences, Eukaryota, Feeding Behavior, Plankton, Invertebrates, Trophic Interactions, Habitats, Community Ecology, Predatory Behavior, Vertebrates, Amniotes, [SDE]Environmental Sciences, Earth Sciences, Medicine, Zoology, Animal Distribution, Research Article
Abstract: International audience; In habitat modelling, environmental variables are assumed to be proxies of lower trophic levels distribution and by extension, of marine top predator distributions. More proximal variables, such as potential prey fields, could refine relationships between top predator distributions and their environment. In situ data on prey distributions are not available over large spatial scales but, a numerical model, the Spatial Ecosystem And POpulation DYnamics Model (SEAPODYM), provides simulations of the biomass and production of zooplankton and six functional groups of micronekton at the global scale. Here, we explored whether generalised additive models fitted to simulated prey distribution data better predicted deep-diver densities (here beaked whales Ziphiidae and sperm whales Physeter macrocephalus ) than models fitted to environmental variables. We assessed whether the combination of environmental and prey distribution data would further improve model fit by comparing their explanatory power. For both taxa, results were suggestive of a preference for habitats associated with topographic features and thermal fronts but also for habitats with an extended euphotic zone and with large prey of the lower mesopelagic layer. For beaked whales, no SEAPODYM variable was selected in the best model that combined the two types of variables, possibly because SEAPODYM does not accurately simulate the organisms on which beaked whales feed on. For sperm whales, the increase model performance was only marginal. SEAPODYM outputs were at best weakly correlated with sightings of deep-diving cetaceans, suggesting SEAPODYM may not accurately predict the prey fields of these taxa. This study was a first investigation and mostly highlighted the importance of the physiographic variables to understand mechanisms that influence the distribution of deep-diving cetaceans. A more systematic use of SEAPODYM could allow to better define the limits of its use and a development of the model that would simulate larger prey beyond 1,000 m would probably better characterise the prey of deep-diving cetaceans.
Published: 2021
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33. Pathways to sustaining tuna-dependent Pacific Island economies during climate change

Author: Simon J. Nicol, Peter A Williams, Sue Taei, Timothy Adams, Glen Holmes, Matthieu Lengaigne, Sangaalofa Clark, William Mansfield, Inna Senina, Thomas Gorgues, Patrick Lehodey, Martin Tsamenyi, Morgane Dessert, Quentin A Hanich, Katherine Seto, Christophe E. Menkès, Beatriz Calmettes, Harriet Harden-Davies, Coral Pasisi, Chis Reid, John M. Hampton, Olivier Aumont, Alex Sen Gupta, Yoshitaka Ota, Marion Gehlen, Espen Ronneberg, Neville Smith, Graham M. Pilling, Johann D. Bell, Steven R. Hare, University of Wollongong [Australia], Collecte Localisation Satellites (CLS), Nucleus for European Modeling of the Ocean (NEMO R&D ), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Parties to the Nauru Agreement Office, Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Communauté du Pacifique/Pacific Community, MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Ecologie marine tropicale des océans Pacifique et Indien (ENTROPIE [Nouvelle-Calédonie]), Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Ifremer - Nouvelle-Calédonie, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de la Nouvelle-Calédonie (UNC), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD), Ifremer - Nouvelle-Calédonie, and Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Université de la Nouvelle-Calédonie (UNC)
Subjects: 0106 biological sciences, 010504 meteorology & atmospheric sciences, Geography, Planning and Development, Climate change, Management, Monitoring, Policy and Law, 01 natural sciences, Effects of global warming, 14. Life underwater, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 0105 earth and related environmental sciences, Nature and Landscape Conservation, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, Ecology, Renewable Energy, Sustainability and the Environment, 010604 marine biology & hydrobiology, Urban Studies, Climate Action, Geography, International waters, Economy, 13. Climate action, Greenhouse gas, Sustainability, Fisheries management, Small Island Developing States, Tuna, Food Science
Abstract: Climate-driven redistribution of tuna threatens to disrupt the economies of Pacific Small Island Developing States (SIDS) and sustainable management of the world’s largest tuna fishery. Here we show that by 2050, under a high greenhouse gas emissions scenario (RCP 8.5), the total biomass of three tuna species in the waters of ten Pacific SIDS could decline by an average of 13% (range = −5% to −20%) due to a greater proportion of fish occurring in the high seas. The potential implications for Pacific Island economies in 2050 include an average decline in purse-seine catch of 20% (range = −10% to −30%), an average annual loss in regional tuna-fishing access fees of US$90 million (range = −US$40 million to –US$140 million) and reductions in government revenue of up to 13% (range = −8% to −17%) for individual Pacific SIDS. Redistribution of tuna under a lower-emissions scenario (RCP 4.5) is projected to reduce the purse-seine catch from the waters of Pacific SIDS by an average of only 3% (range = −12% to +9%), indicating that even greater reductions in greenhouse gas emissions, in line with the Paris Agreement, would provide a pathway to sustainability for tuna-dependent Pacific Island economies. An additional pathway involves Pacific SIDS negotiating within the regional fisheries management organization to maintain the present-day benefits they receive from tuna, regardless of the effects of climate change on the distribution of the fish. Climate change will alter the distribution of tuna, impacting the economies of Pacific Small Island Developing States. This study finds that greater greenhouse gas emissions will worsen these impacts.
Published: 2021
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34. Directional and Frequency Spread of Surface Ocean Waves from CFOSAT/SWIM Measurements

Author: E. Le Merle, Patricia Schippers, Charles Peureux, Christophe Dufour, Danièle Hauser, Lotfi Aouf, SPACE - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Météo France, Analytic and Computational Research, Inc. - Earth Sciences (ACRI-ST), and Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)
Subjects: ocean wave spectra, 020209 energy, 02 engineering and technology, 01 natural sciences, 010305 fluids & plasmas, law.invention, Wave model, law, ocean waves, 0103 physical sciences, Wind wave, 0202 electrical engineering, electronic engineering, information engineering, 14. Life underwater, Rogue wave, Radar, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], CFOSAT, SWIM, Geodesy, ocean, Wavelength, Surface wave, Satellite, Significant wave height, Geology, radar
Abstract: International audience; The CFOSAT (China France Oceanography Satellite) mission launched in 2018 now routinely provides at the global scale, directional spectra of ocean waves. The principle is based on the analysis of the normalized radar cross-section measured by the instrument SWIM (Surface Waves Investigation and Monitoring), a near-nadir pointing Ku-Band real-aperture scanning radar. From the ocean wave spectra derived from SWIM, the principal parameters of ocean wave spectra as significant wave height, peak wavelength, and peak direction are now available to better characterize the sea-state. However, it is known that these principal parameters are not sufficient not fully characterize the distribution of wave energy and understand or validate the physical processes impacting its evolution during growth order decay. Here we show that the parameters characterizing the shape of the wave spectra (e.g directional and frequency spread) can be estimated at the global scale from the SWIM measurements. We also show that they can provide consistent values of the Benjamin-Feir index, an index proposed to estimate the probability of extreme waves. Similarities of differences with the shape parameters of the MFWAM numerical wave model are also discussed.
Published: 2021
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35. A combined use of in situ and satellite-derived observations to characterize surface hydrology and its variability in the Congo River Basin

Author: Fabrice Papa, Melanie Becker, Adrien Paris, Benjamin Kitambo, Mohammad J. Tourian, Ayan Santos Fleischmann, Catherine Prigent, Frédéric Frappart, Stéphane Calmant, Raphael Tshimanga, Johary Andriambeloson, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), University of Kinshasa (UNIKIN), Universidade Federal do Rio Grande do Sul [Porto Alegre] (UFRGS), LIttoral ENvironnement et Sociétés - UMR 7266 (LIENSs), Institut national des sciences de l'Univers (INSU - CNRS)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), University of Stuttgart, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères (LERMA (UMR_8112)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Université d'Antananarivo, Interactions Sol Plante Atmosphère (UMR ISPA), Ecole Nationale Supérieure des Sciences Agronomiques de Bordeaux-Aquitaine (Bordeaux Sciences Agro)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), and Centre National d'Études Spatiales [Toulouse] (CNES)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)
Subjects: Hydrology, geography, geography.geographical_feature_category, Flood myth, Drainage basin, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Structural basin, Spatial distribution, 6. Clean water, Hydrology (agriculture), 13. Climate action, [SDU]Sciences of the Universe [physics], Tributary, Environmental science, Stage (hydrology), [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology, Surface water
Abstract: The Congo River basin (CRB) is the second largest river system in the world, but its hydroclimatic characteristics remain relatively poorly known. Here, we jointly analyse a large record of in situ and satellite-derived observations, including a long-term time series of surface water height (SWH) from radar altimetry (a total of 2311 virtual stations) and surface water extent (SWE) from a multi-satellite technique, to characterize the CRB surface hydrology and its variability. First, we show that SWH from altimetry multi-missions agrees well with in situ water stage at various locations, with the root mean square deviation varying from 10 cm (with Sentinel-3A) to 75 cm (with European Remote Sensing satellite-2). SWE variability from multi-satellite observations also shows a plausible behaviour over a ∼25-year period when evaluated against in situ observations from the subbasin to basin scale. Both datasets help to better characterize the large spatial and temporal variability in hydrological patterns across the basin, with SWH exhibiting an annual amplitude of more than 5 m in the northern subbasins, while the Congo River main stream and Cuvette Centrale tributaries vary in smaller proportions (1.5 to 4.5 m). Furthermore, SWH and SWE help illustrate the spatial distribution and different timings of the CRB annual flood dynamic and how each subbasin and tributary contribute to the hydrological regime at the outlet of the basin (the Brazzaville/Kinshasa station), including its peculiar bimodal pattern. Across the basin, we estimate the time lag and water travel time to reach the Brazzaville/Kinshasa station to range from 0–1 month in its vicinity in downstream parts of the basin and up to 3 months in remote areas and small tributaries. Northern subbasins and the central Congo region contribute highly to the large peak in December–January, while the southern part of the basin supplies water to both hydrological peaks, in particular to the moderate one in April–May. The results are supported using in situ observations at several locations in the basin. Our results contribute to a better characterization of the hydrological variability in the CRB and represent an unprecedented source of information for hydrological modelling and to study hydrological processes over the region.
Published: 2021
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36. A 1D-Var Approach to Retrieve Clear-Sky Wet Tropospheric Correction from Current and Future Altimetry Missions

Author: Laura Hermozo, Bruno Picard, Mickael Pardé, Laurence Eymard, Fatima Karbou, Collecte Localisation Satellites (CLS), Observatoire des sciences de l'univers Ecce Terra [Paris] (OSU ECCE TERRA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes de la Neige (CEN), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, media_common.quotation_subject, 0211 other engineering and technologies, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Ocean Engineering, 02 engineering and technology, 01 natural sciences, Atmosphere, Current (stream), Troposphere, Data assimilation, Sky, Radiative transfer, Environmental science, Altimeter, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, media_common, Remote sensing
Abstract: Statistical methods are usually used to provide estimations of the wet tropospheric correction (WTC), necessary to correct altimetry measurements for atmospheric path delays, using brightness temperatures measured at two or three low frequencies from a passive microwave radiometer on board the altimeter mission. Despite their overall accuracy over oceanic surfaces, uncertainties still remain in specific regions of complex atmospheric stratification. Thus, there is still a need to improve the methods currently used by taking into account the frequency-dependent information content of the observations and the atmospheric and surface variations in the surroundings of the observations. In this article we focus on the assimilation of relevant passive microwave observations to retrieve the WTC over ocean using different altimeter mission contexts (current and future, providing brightness temperature measurements at higher frequencies in addition to classical low frequencies). Data assimilation is performed using a one-dimensional variational data assimilation (1D-Var) method. The behavior of the 1D-Var is evaluated by verifying its physical consistency when using pseudo- and real observations. Several observing-system simulation experiments are run and their results are analyzed to evaluate global and regional WTC retrievals. Comparisons of 1D-Var-based TWC retrieval and reference products from classical WTC retrieval algorithms or radio-occultation data are also performed to assess the 1D-Var performances.
Published: 2019
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37. Impact of Tropical Cyclones on Inhabited Areas of the SWIO Basin at Present and Future Horizons. Part 2: Modeling Component of the Research Program RENOVRISK-CYCLONE

Author: Fabrice Chauvin, Olivier Bousquet, Jonas Zucule, Frauke Fleischer-Dogley, Quoc-Phi Duong, Edouard Lees, Romain Husson, Alexis Mouche, Callum Thompson, Emmanuel Cordier, François Bonnardot, Radiance Calmer, Navalona Manitriniana Ravoson, Guilhem Barruol, Vincent Amelie, M. Singh, Julien Cattiaux, Bruno Razafindradina, Nicolas Marquestaut, Sylvie Malardel, Alberto Mavume, Chia-Lun Tsai, Stéphane Ciccione, Dominique Mekies, Soline Bielli, Joris Pianezze, M Claeys, E. J. Rindraharisaona, Christelle Barthe, Lova Zakariasy, Gregory Roberts, Pierre Tulet, Jonathan Durand, Marie-Noëlle Bouin, Laboratoire de l'Atmosphère et des Cyclones (LACy), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Météo France, Laboratoire d'aérologie (LAERO), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Institute for Coastal Marine Research (CMR), Nelson Mandela University, Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Center for Atmospheric REmote Sensing (CARE), Kyungpook National University [Daegu], Direction Interrégionale de Météo-Franc pour l'océan Indien, Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Seychelles Meteorological Authority, Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire GéoSciences Réunion (LGSR), Université de La Réunion (UR)-Institut de Physique du Globe de Paris, National Snow and Ice Data Center (NSIDC), University of Colorado [Boulder], Kélonia - Observatoire des tortues marines, Observatoire des Sciences de l'Univers de La Réunion (OSU-Réunion), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR), Seychelles Islands Foundation (SIF), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Eduardo Mondlane University, Institut et Observatoire de Géophysique d’Antisiranana (IOGA), Institut Supérieur de Technologie d’Antisiranana, Scripps Institution of Oceanography (SIO), University of California [San Diego] (UC San Diego), University of California-University of California, Mauritius Oceanography Institute, University of Mauritius, Instituto Nacional de Meteorologia (INAM), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Météo-France, Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Kyungpook National University [Daegu] (KNU), Direction Interrégionale de Météo-France pour l'océan Indien (DIROI), Météo-France, Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris), Scripps Institution of Oceanography (SIO - UC San Diego), and University of California (UC)-University of California (UC)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, tropical cyclone, ocean-wave-atmosphere coupling, Climate change, Context (language use), Environmental Science (miscellaneous), 01 natural sciences, Meteorology. Climatology, 14. Life underwater, climate modeling, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, cloud-resolving model, geography.geographical_feature_category, Microphysics, 010505 oceanography, Global warming, ocean–wave–atmosphere coupling, 13. Climate action, Climatology, Archipelago, south-west Indian ocean, Environmental science, Cyclone, Climate model, Tropical cyclone, QC851-999
Abstract: International audience; The ReNovRisk-Cyclone program aimed at developing an observation network in the south-west Indian ocean (SWIO) in close synergy with the implementation of numerical tools to model and analyze the impacts of tropical cyclones (TC) in the present and in a context of climate change. This paper addresses the modeling part of the program. First, a unique coupled system to simulate TCs in the SWIO is developed. The ocean–wave–atmosphere coupling is considered along with a coherent coupling between sea surface state, wind field, aerosol, microphysics, and radiation. This coupled system is illustrated through several simulations of TCs: the impact of air–sea flux parameterizations on the evolution of TC Fantala is examined, the full coupling developed during the program is illustrated on TC Idai, and the potential of novel observations like space-borne synthetic aperture radar and sea turtles to validate the atmosphere and ocean models is presented with TC Herold. Secondly, the evolution of cyclonic activity in the SWIO during the second half of the 21st century is assessed. It was addressed both using climate simulation and through the implementation of a pseudo global warming method in the high-resolution coupled modeling platform. Our results suggest that the Mascarene Archipelago should experience an increase of TC related hazards in the medium term.
Published: 2021
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38. Atlas de marée de l'océan global FES2014: conception et performance

Author: Lyard, Florent, Allain, Damien, Cancet, Mathilde, Carrère, Loren, Picot, Nicolas, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), NOVELTIS LABEGE FRA, Partenaires IRSTEA, Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Centre National d'Études Spatiales [Toulouse] (CNES), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2021
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39. NOUVELLE DISTRIBUTION VERTICALE GLOBALE DE LA CONCENTRATION DE CARBONE ORGANIQUE PARTICULAIRE ET DE CHLOROPHYLLE-A MAILLEE, UTILISANT L'APPRENTISSAGE AUTOMATIQUE POUR LE CMEMS

Author: Sauzède, Raphaëlle, Claustre, Hervé, Pannimpullath, Remanan, Uitz, Julia, Guinehut, Stéphanie, Collecte Localisation Satellites (CLS), Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Shom, Ifremer, EuroGOOS AISBL, and Institut de la Mer de Villefranche, CNRS-INSU, Sorbonne Université, Villefranche-Sur-Mer, France
Subjects: Multi-observations, Chlorophyll-a concentration, Machine learning, [SDE]Environmental Sciences, CMEMS, Particulate organic carbon
Abstract: International audience; As part of Copernicus Marine Environmental Monitoring Service (CMEMS), the multi-observations thematic assembly center aims to provide products based on observations and data fusion techniques (Guinehut et al., 2021). Sauzede et al., (2016) have demonstrated the potential of using hydrological measurements and ocean color satellite observations to infer the vertical distribution of backscattering coeffi cient, a proxy for the stock of particulate organic carbon (POC). The 'Satellite Ocean-Color merged with Argo data to infer bio-optical properties to depth' (SOCA) method is a neural-network-based method trained using the Biogeochemical-Argo database. SOCA has been upgraded to improve the POC retrieval and additionally retrieve the chlorophyll-a concentration (Chl). Using this method with CMEMS hydrological and satellite products, weekly 3-dimensional fi elds of POC and associated uncertainty were retrieved for the 1998-2018 period and made available from the CMEMS online portal since July 2020. The 3-dimensional products of SOCA-retrieved Chl will be made available by the end of 2021. Both of these products will be updated yearly as new input data become available. These new CMEMS products represent a most valuable source of data useful not only for supporting the quality control of Biogeochemical-Argo fl oat observations but also for data assimilation and initialization/validation of biogeochemical models.
Published: 2021

40. LE CENTRE D'ASSEMBLAGE THÉMATIQUE MULTI-OBSERVATIONS DU SERVICE DE SURVEILLANCE DE L'ENVIRONNEMENT MARIN COPERNICUS

Author: Bruno Buongiorno Nardelli, Eric Greiner, Stephanie Guinehut, Hélène Etienne, Hervé Claustre, Solene Jousset, Sandrine Mulet, Trang Chau, Daniele Ciani, Raphaëlle Sauzède, Nathalie Verbrugge, Frédéric Chevallier, Marion Gehlen, Collecte Localisation Satellites (CLS), Consiglio Nazionale delle Ricerche [Napoli] (CNR), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Consiglio Nazionale delle la Ricerche, Istituto di Scienze Marine, Rome, Italy, Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Shom, Ifremer, EuroGOOS AISBL, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Observatoire océanologique de Villefranche-sur-mer (OOVM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
Subjects: Service (systems architecture), satellite, in situ, data fusion techniques, Sensor fusion, multi observations, Thematic map, 13. Climate action, [SDE]Environmental Sciences, Satellite, 14. Life underwater, CMEMS, Scale (map), Remote sensing, Copernicus
Abstract: Complementary to ocean state estimate provided by modelling/assimilation systems, a multi observations-based approach is available through the MULTI OSERVATIONS (MULTIOBS) Thematic Assembly Center (TAC) of the European Copernicus Marine Environment Monitoring Service (CMEMS).CMEMS MULTIOBS TAC proposes products based on satellite & in situ observations and state-of-the-art data fusion techniques. These products are fully qualified and documented and, are distributed through the CMEMS catalogue (http://marine.copernicus.eu/services-portfolio). They cover the global ocean for physical and biogeochemical (BGC) variables. They are available in Near-Real-Time (NRT) or as Multi-Year Products (MYP) for the past 28 to 36 years.Satellite input observations include altimetry but also sea surface temperature, sea surface salinity as well as ocean color. In situ observations of physical and BGC variables are from autonomous platform such as Argo, moorings and ship-based measurements. Data fusion techniques are based on multiple linear regression method, multidimensional optimal interpolation method or neural networks.MULTIOBS TAC provides the following products at global scale:3D temperature, salinity and geostrophic current fields, both in NRT and as MYP; 2D sea surface salinity and sea surface density fields, both in NRT and as MYP; 2D total surface and near-surface currents, both in NRT and as MYP; 3D vertical current as MYP; 2D surface carbon fields of CO2 flux (fgCO2), pCO2 and pH as MYP; Nutrient vertical distribution (including nitrate, phosphate and silicate) profiles as MYP; 3D Particulate Organic Carbon (POC) and Chlorophyll-a (Chl-a) fields as MYP. Furthermore, MULTIOBS TAC provides specific Ocean Monitoring Indicators (OMIs), based on the above products, to monitor the global ocean 3D hydrographic variability patterns (water masses) and the global ocean carbon sink.
Published: 2021

41. Impact of Tropical Cyclones on Inhabited Areas of the SWIO Basin at Present and Future Horizons. Part 1: Overview and Observing Component of the Research Project RENOVRISK-CYCLONE

Author: Joris Pianezze, M Claeys, E. J. Rindraharisaona, Pierre Tulet, Bruno Razafindradina, Guilhem Barruol, Romain Husson, Callum Thompson, François Bonnardot, Chia-Lun Tsai, Frauke Fleischer-Dogley, Christelle Barthe, Lova Zakariasy, M. Singh, Julien Cattiaux, Nicolas Marquestaut, Alberto Mavume, Fabrice Chauvin, Stéphane Ciccione, Jonas Zucule, Dominique Mekies, Gregory Roberts, Jonathan Durand, Olivier Bousquet, Emmanuel Cordier, Edouard Lees, Alexis Mouche, Radiance Calmer, Vincent Amelie, Soline Bielli, Laboratoire de l'Atmosphère et des Cyclones (LACy), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Météo-France, Institute for Coastal Marine Research (CMR), Nelson Mandela University, Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Observatoire des Sciences de l'Univers de La Réunion (OSU-Réunion), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR), Laboratoire d'aérologie (LAERO), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), National Snow and Ice Data Center (NSIDC), University of Colorado [Boulder], Laboratoire GéoSciences Réunion (LGSR), Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Scripps Institution of Oceanography (SIO - UC San Diego), University of California [San Diego] (UC San Diego), University of California (UC)-University of California (UC), Seychelles Meteorological Authority, Seychelles Islands Foundation (SIF), Eduardo Mondlane University, Institut Supérieur de Technologie d’Antisiranana, Direction Interrégionale de Météo-France pour l'océan Indien (DIROI), Météo-France, Mauritius Oceanography Institute, University of Mauritius, Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Kélonia - Observatoire des tortues marines, Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Météo France, Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Université de La Réunion (UR)-Institut de Physique du Globe de Paris, Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Scripps Institution of Oceanography (SIO), University of California-University of California, Direction Interrégionale de Météo-Franc pour l'océan Indien, and Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, tropical cyclone, gliders, Satellite system, Environmental Science (miscellaneous), Structural basin, sea turtles, 010502 geochemistry & geophysics, 01 natural sciences, seismic data, biologging, Meteorology. Climatology, 14. Life underwater, south-west Indian Ocean, unmanned airborne system, 0105 earth and related environmental sciences, Atmospheric sounding, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, global satellite navigation system, ReNovRisk, austral and cyclonic swells, numerical modelling, climate modelling, Drone, Swell, 13. Climate action, GNSS applications, Cyclone, Environmental science, QC851-999, Tropical cyclone
Abstract: International audience; The international research program “ReNovRisk-CYCLONE” (RNR-CYC, 2017–2021) directly involves 20 partners from 5 countries of the south-west Indian-Ocean. It aims at improving the observation and modelling of tropical cyclones in the south-west Indian Ocean, as well as to foster regional cooperation and improve public policies adapted to present and future tropical cyclones risk in this cyclonic basin. This paper describes the structure and main objectives of this ambitious research project, with emphasis on its observing components, which allowed integrating numbers of innovative atmospheric and oceanic observations (sea-turtle borne and seismic data, unmanned airborne system, ocean gliders), as well as combining standard and original methods (radiosoundings and global navigation satellite system (GNSS) atmospheric soundings, seismic and in-situ swell sampling, drone and satellite imaging) to support research on tropical cyclones from the local to the basin-scale.
Published: 2021
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42. C-Band SAR Winds for Tropical Cyclone Monitoring and Forecast in the South-West Indian Ocean

Author: Quoc-Phi Duong, Christophe Payan, Sébastien Langlade, Romain Husson, Alexis Mouche, Sylvie Malardel, Laboratoire de l'Atmosphère et des Cyclones (LACy), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Météo-France, Direction Interrégionale de Météo-France pour l'océan Indien (DIROI), Météo-France, Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Collecte Localisation Satellites (CLS), Laboratoire d'Océanographie Physique et Spatiale (LOPS), and Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, C band, tropical cyclone, 3D-Var, 0211 other engineering and technologies, 02 engineering and technology, Environmental Science (miscellaneous), Structural basin, 01 natural sciences, Wind speed, law.invention, Data assimilation, law, Meteorology. Climatology, Radar, sentinel, data assimilation, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 13. Climate action, Climatology, Cyclone, Environmental science, IDAI, QC851-999, Tropical cyclone, GELENA, Intensity (heat transfer), SAR
Abstract: International audience; Tropical cyclone (TC) monitoring and forecast in the South West Indian Ocean (SWIO) basin remain challenging, notably because of the lack of direct observations. During the 2018–2019 cyclone season, S-1 Sentinel SAR images were acquired, as part of the ReNovRisk-Cyclone research program, giving access to unprecedented detailed TC wind structure description without wind speed limitation. This paper assesses the quality of these data and the impact of their assimilation for TC forecasts. SAR observations are compared with analyses from a convection-permitting, limited area model AROME OI 3D-Var and with wind products used for operational TC monitoring. Their bias depends on the angle of incidence of the radar and the observation error is larger for extreme wind speed. The impact of SAR assimilation in AROME OI 3D-Var is assessed through two case studies. In the TC GELENA case, it leads to a better TC positioning and an improved representation of inner and outer vortex structures. The TC intensity reduction in the analysis propagates through subsequent analyses and it has an impact on forecasts for around 12 h. In the TC IDAI case, the 3D-Var does not manage to reproduce TC intensity captured by SAR. In both cases, the modification of the initial conditions has little influence on the intensification rate of the model forecasts. Sensitivity tests show that these results are robust to different observation errors and thinning.
Published: 2021
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43. New Directional Wave Satellite Observations: Towards Improved Wave Forecasts and Climate Description in Southern Ocean

Author: Danièle Hauser, Cedric Tourain, Charles Peureux, Alessandro Toffoli, Lotfi Aouf, Bertrand Chapron, Centre national de recherches météorologiques (CNRM), Météo France-Centre National de la Recherche Scientifique (CNRS), SPACE - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), University of Melbourne, Centre National d'Études Spatiales [Toulouse] (CNES), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Météo France-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Centre National d'Études Spatiales [Toulouse] (CNES)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, 01 natural sciences, Physics::Geophysics, Wind wave, Wavenumber, 14. Life underwater, Southern Ocean, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Physics::Atmospheric and Oceanic Physics, SWH, 0105 earth and related environmental sciences, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], assimilation, 010505 oceanography, Fetch, Westerlies, Swell, Wavelength, Geophysics, directional, 13. Climate action, wave age, Climatology, General Earth and Planetary Sciences, Satellite, wave number, Significant wave height, Geology
Abstract: In spite of continuous improvements of ocean wave models in the last decades, large errors still remain in particular under strongly forced conditions, often encountered in the Southern Ocean, where strong westerly winds generate some of the fiercest waves on Earth in almost unlimited fetch conditions. The newly launched China‐France Oceanography SATellite (CFOSAT) provides directional spectra of ocean waves for both wind seas and swells. Compared to Synthetic Aperture Radar (SAR), it can resolve shorter wavelengths in all directions, which dominate in non‐fully developed wind waves. Here, the assimilation of these CFOSAT wave number components is proved to bring more accurate predictions of wave growth compared to the assimilation of significant wave height alone. A notable reduction of model bias is found in the Southern Ocean, especially in the Pacific Ocean sector. Results further exhibit a downward shift of the wave age, consistent with theoretical wave growth curves. Plain Language Summary This work focuses on the importance of using directional wave observations to improve model wave prediction in the Southern Ocean. The results indicate a significant impact on the transition from a wind‐dependent sea to a well‐developed sea. A direct consequence of this work will concern a better understanding of the wave climate in the Southern Ocean and therefore an improvement of coupled ocean/waves/atmosphere systems.
Published: 2021
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44. Reconstructing Ocean Surface Current Combining Altimetry and Future Spaceborne Doppler Data

Author: Clement Ubelmann, Gérald Dibarboure, Lucile Gaultier, Aurélien Ponte, Fabrice Ardhuin, Maxime Ballarotta, Yannice Faugère, OceanNext, Centre National d'Études Spatiales [Toulouse] (CNES), OceanDataLab, Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), and Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], 010504 meteorology & atmospheric sciences, Surface ocean, Gaussian, Ocean current, Oceanography, 01 natural sciences, symbols.namesake, Geophysics, Space and Planetary Science, Geochemistry and Petrology, 13. Climate action, Earth and Planetary Sciences (miscellaneous), symbols, Satellite, Altimeter, 14. Life underwater, Current (fluid), Doppler effect, Physics::Atmospheric and Oceanic Physics, Geology, Sea level, 0105 earth and related environmental sciences, Remote sensing
Abstract: Two methods for the mapping of ocean surface currents from satellite measurements of sea level and future current vectors are presented and contrasted. Both methods rely on the linear and Gaussian analysis framework with different levels of covariance definitions. The first method separately maps sea level and currents with single‐scale covariance functions and leads to estimates of the geostrophic and ageostrophic circulations. The second maps both measurements simultaneously and projects the circulation onto 4 contributions: geostrophic, ageostrophic rotary, ageostrophic divergent and inertial. When compared to the first method, the second mapping moderately improves the resolution of geostrophic currents but significantly improves estimates of the ageostrophic circulation, in particular near‐inertial oscillations. This method offers promising perspectives for reconstructions of the ocean surface circulation. Even the hourly dynamics can be reconstructed from measurements made locally every few days because nearby measurements are coherent enough to help fill the gaps. Based on numerical simulation of ocean surface currents, the proposed SKIM mission that combines a nadir altimeter and a Doppler scatterometer with a 300 km wide swath (with a mean revisit time of 3 days) would allow the reconstruction of 50% of the near‐inertial variance around an 18 hour period of oscillation. Plain Language Summary Ocean surface currents are caused by a variety of phenomena that varies at different space and time scales. Here we mainly consider the two dominant contributions. The first is the current resulting from the quasi‐equilibrium between the sloping sea level and the Coriolis force, slowly evolving over a few days. The second is also associated with the Coriolis force, but out of equilibrium: oscillating currents caused by rapid changes of the wind with a narrow range of periods around a natural period of oscillation that increase with latitude from 12 hours at the poles. For many applications it is desirable to separate these two contributions, for example to compute transports associated to the slowly evolving component and to evaluate the amount of kinetic energy pumped by the wind, mostly in the fast oscillations. This separation is easy with hourly sampled in situ measurements, but few are available. Here we show that we can perform this separation using satellite passes with measurements of sea level and a swath of surface current vectors, as can be measured by proposed future satellites. The fast oscillations can be reproduced even if data is available every few days, thanks to their spatial patterns and temporal coherence.
Published: 2021
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45. The new CNES-CLS18 Global Mean Dynamic Topography

Author: S. Mulet, M.-H. Rio, H. Etienne, C. Artana, M. Cancet, G. Dibarboure, H. Feng, R. Husson, N. Picot, C. Provost, P. T. Strub, Collecte Localisation Satellites (CLS), Agence Spatiale Européenne (ESA), European Space Agency (ESA), Mercator Océan, Société Civile CNRS Ifremer IRD Météo-France SHOM, Austral, Boréal et Carbone (ABC), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), NOVELTIS [Sté], Centre National d'Études Spatiales [Toulouse] (CNES), University of New Hampshire (UNH), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Oregon State University (OSU), Agence Spatiale Européenne = European Space Agency (ESA), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: Data processing, 010504 meteorology & atmospheric sciences, Buoy, 010505 oceanography, Ocean current, General Medicine, Geodesy, 01 natural sciences, Environmental sciences, Ocean surface topography, Geoid, Geography. Anthropology. Recreation, GE1-350, 14. Life underwater, Altimeter, Geology, Geostrophic wind, Argo, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences
Abstract: The Mean Dynamic Topography (MDT) is a key reference surface for altimetry. It is needed for the calculation of the ocean absolute dynamic topography, and under the geostrophic approximation, the estimation of surface currents. CNES-CLS Mean Dynamic Topography (MDT) solutions are calculated by merging information from altimeter data, GRACE and GOCE gravity field and oceanographic in-situ measurements (drifting buoy velocities, hydrological profiles). The objective of this paper is to present the newly updated CNES-CLS18 MDT. The main improvement compared to the previous CNES-CLS13 solution is the use of updated input datasets: the GOCO05S geoid model is used based on the complete GOCE mission (November 2009–October 2013) and 10.5 years of GRACE data, together with all drifting buoy velocities (SVP-type and Argo floats) and hydrological profiles (CORA database) available from 1993–2017 (instead of 1993–2012). The new solution also benefits from improved data processing – in particular a new wind-driven current model has been developed to extract the geostrophic component from the buoy velocities; and methodology – in particular the computation of the medium scale GOCE-based MDT first guess and the correlation scales used for the multivariate mapping have been revised. An evaluation of the new solution compared to the previous version and to other existing MDT show significant improvements both in strong currents and coastal areas.
Published: 2021
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46. GeoTrackNet-A Maritime Anomaly Detector using Probabilistic Neural Network Representation of AIS Tracks and A Contrario Detection

Author: Rene Garello, Duong Nguyen, Rodolphe Vadaine, Ronan Fablet, Guillaume Hajduch, Département Signal et Communications (IMT Atlantique - SC), IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), GEVES Station nationale d'essais de semences, Institut National de la Recherche Agronomique (INRA), Collecte Localisation Satellites (CLS), Département lmage et Traitement Information (IMT Atlantique - ITI), Lab-STICC_TB_CID_TOMS, Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Télécom Bretagne-Institut Brestois du Numérique et des Mathématiques (IBNM), Université de Brest (UBO)-Université européenne de Bretagne - European University of Brittany (UEB)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Télécom Bretagne-Institut Brestois du Numérique et des Mathématiques (IBNM), Université de Brest (UBO)-Université européenne de Bretagne - European University of Brittany (UEB)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS), Département Mathematical and Electrical Engineering (IMT Atlantique - MEE), Equipe Observations Signal & Environnement (Lab-STICC_OSE), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), and Institut Mines-Télécom [Paris] (IMT)
Subjects: FOS: Computer and information sciences, Computer Science - Machine Learning, Situation awareness, Computer Science - Artificial Intelligence, Computer science, Machine Learning (stat.ML), computer.software_genre, GeneralLiterature_MISCELLANEOUS, Machine Learning (cs.LG), [INFO.INFO-AI]Computer Science [cs]/Artificial Intelligence [cs.AI], a contrario detection, Probabilistic neural network, maritime surveillance, [INFO.INFO-LG]Computer Science [cs]/Machine Learning [cs.LG], Statistics - Machine Learning, 0502 economics and business, Index Terms-AIS, 050210 logistics & transportation, Artificial neural network, Data stream mining, business.industry, Mechanical Engineering, Deep learning, 05 social sciences, AIS, variational recurrent neural networks, Probabilistic logic, deep learning, anomaly detection, Computer Science Applications, Artificial Intelligence (cs.AI), ComputingMethodologies_PATTERNRECOGNITION, Automotive Engineering, Key (cryptography), Anomaly detection, Data mining, Artificial intelligence, business, computer
Abstract: Representing maritime traffic patterns and detecting anomalies from them are key to vessel monitoring and maritime situational awareness. We propose a novel approach -- referred to as GeoTrackNet -- for maritime anomaly detection from AIS data streams. Our model exploits state-of-the-art neural network schemes to learn a probabilistic representation of AIS tracks and a contrario detection to detect abnormal events. The neural network provides a new means to capture complex and heterogeneous patterns in vessels' behaviours, while the \textit{a contrario} detector takes into account the fact that the learnt distribution may be location-dependent. Experiments on a real AIS dataset comprising more than 4.2 million AIS messages demonstrate the relevance of the proposed method compared with state-of-the-art schemes., Comment: IEEE Transactions on Intelligent Transportation Systems
Published: 2021
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47. Local sea level trends, accelerations and uncertainties over 1993–2019

Author: Aurélien Ribes, Giorgio Spada, Pierre Prandi, Benoit Meyssignac, Jérôme Benveniste, Michael Ablain, Collecte Localisation Satellites (CLS), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Prandi, Pierre, Meyssignac, Benoit, Ablain, Michaël, Spada, Giorgio, Ribes, Aurélien, and Benveniste, Jérôme
Subjects: Statistics and Probability, Data Descriptor, 010504 meteorology & atmospheric sciences, Meteorology, SURFACE, Calibration (statistics), IMPACT, Science, Climate science, Library and Information Sciences, 01 natural sciences, Education, JASON-1, Range (statistics), 14. Life underwater, Sensitivity (control systems), Sea level, Physics::Atmospheric and Oceanic Physics, ERROR, 0105 earth and related environmental sciences, PATH DELAYS, CALIBRATION, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, TOPEX/POSEIDON, 010505 oceanography, Physical oceanography, Natural hazards, Ranging, RECORD, SATELLITE ALTIMETRY, Confidence interval, Computer Science Applications, MODEL, 13. Climate action, Satellite altimetry, Environmental science, Statistics, Probability and Uncertainty, Climate-change impacts, Information Systems
Abstract: Satellite altimetry missions provide a quasi-global synoptic view of sea level variations over more than 25 years and provide regional sea level (SL) indicators such as trends and accelerations. Estimating realistic uncertainties on these quantities is crucial to address current climate science questions. While uncertainty estimates are available for the global mean sea level (GMSL), information is not available at local scales so far. We estimate a local satellite altimetry error budget and use it to derive local error variance-covariance matrices, and estimate confidence intervals on trends and accelerations at the 90% confidence level. Over 1993–2019, we find that the average local sea level trend uncertainty is 0.83 mm.yr−1 with values ranging from 0.78 to 1.22 mm.yr−1. For accelerations, uncertainties range from 0.057 to 0.12 mm.yr−1, with a mean value of 0.062. We also perform a sensitivity study to investigate a range of plausible error budgets. Local error levels, error variance-covariance matrices, SL trends and accelerations, along with corresponding uncertainties are provided., Measurement(s) sea surface height Technology Type(s) satellite radar altimetry Factor Type(s) year of data collection Sample Characteristic - Environment sea • ocean Sample Characteristic - Location global Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.13297757
Published: 2021
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48. The X-TRACK/ALES multi-mission processing system: New advances in altimetry towards the coast

Author: Florence Birol, Christian Schwatke, Anny Cazenave, Marcello Passaro, Francisco M. Calafat, Fernando Niño, Andy Shaw, Fabien Léger, Yvan Gouzenes, Jean-François Legeais, Jérôme Benveniste, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Collecte Localisation Satellites (CLS), and Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, Ocean current, Coastal ocean, Aerospace Engineering, Climate change, Astronomy and Astrophysics, Context (language use), Track (rail transport), 01 natural sciences, Geophysics, Mediterranean sea, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Climatology, 0103 physical sciences, General Earth and Planetary Sciences, Tide gauge, Satellite altimetry, Sea level, Altimeter, 010303 astronomy & astrophysics, Geology, 0105 earth and related environmental sciences
Abstract: International audience; In the context of the ESA Climate Change Initiative project, a new coastal sea level altimetry product has been developed in order to support advances in coastal sea level variability studies. Measurements from Jason-1,2&3 missions have been retracked with the Adaptive Leading Edge Subwaveform (ALES) Retracker and then ingested in the X-TRACK software with the best possible set of altimetry corrections. These two coastal altimetry processing approaches, previously successfully validated and applied to coastal sea level research, are combined here for the first time in order to derive a 16-year-long (June 2002 to May 2018), high-resolution (20-Hz), along-track sea level dataset in six regions: Northeast Atlantic, Mediterranean Sea, West Africa, North Indian Ocean, Southeast Asia and Australia. The study demonstrates that this new coastal sea level product called X-TRACK/ALES is able to extend the spatial coverage of sea level altimetry data ~3.5 km in the land direction, when compared to the X-TRACK 1-Hz dataset. We also observe a large improvement in coastal sea level data availability from Jason-1 to Jason-3, with data at 3.6 km, 1.9 km and 0.9 km to the coast on average, for Jason-1, Jason-2 and Jason-3, respectively. When combining measurements from Jason-1 to Jason-3, we reach a distance of 1.2-4 km to the coast. When compared to tide gauge data, the accuracy of the new altimetry near-shore sea level estimations also improves. In terms of correlations with a large set of independent tide gauge observations selected in the six regions, we obtain an average value of 0.77. We also show that it is now possible to derive from the X-TRACK/ALES product an estimation of the ocean current variability up to 5 km to the coast. This new altimetry dataset, freely available, will provide a valuable contribution of altimetry in coastal marine research community.
Published: 2021
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49. Changes in Atlantic Water Circulation Patterns and Volume Transports North of Svalbard Over the Last 12 Years (2008–2020)

Author: Nathalie Sennéchael, Gilles Garric, Marylou Athanase, P. Prandi, Camila Artana, M. Dolores Pérez-Hernández, Jean-Michel Lellouche, Christine Provost, Cécilia Bertosio, Austral, Boréal et Carbone (ABC), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Mercator Océan, Société Civile CNRS Ifremer IRD Météo-France SHOM, Université de Las Palmas de Gran Canaria [Espagne] (ULPGC), Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), IAOOS grant A18JROI002 at Sorbonne University, ANR-14-AORS-0003,PAN-ARCTIC OPTIONS,PAN-ARTIC OPTIONS: HOLISTIC INTEGRATION FOR ARCTIC COASTAL-MARINE SUSTAINABILITY(2014), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, Plateau, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Nansen Basin, Continental shelf, [SDE.MCG]Environmental Sciences/Global Changes, Mesoscale meteorology, Oceanography, 01 natural sciences, Boundary current, Current (stream), Geophysics, Circulation (fluid dynamics), 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Submarine pipeline, 14. Life underwater, Geology, 0105 earth and related environmental sciences
Abstract: International audience; tlantic Water (AW) enters the Arctic through Fram Strait as the West Spitsbergen Current (WSC). When reaching the south of Yermak Plateau, the WSC splits into the Svalbard, Yermak Pass, and Yermak Branches. Downstream of Yermak Plateau, AW pathways remain unclear and uncertainties persist on how AW branches eventually merge and contribute to the boundary current along the continental slope. We took advantage of the good performance of the 1/12° Mercator Ocean model in the Western Nansen Basin (WNB) to examine the AW circulation and volume transports in the area. The model showed that the circulation changed in 2008–2020. The Yermak Branch (YB) strengthened over the northern Yermak Plateau, feeding the Return YB along the eastern flank of the Plateau. West of Yermak Plateau, the Transpolar Drift likely shifted westward while AW recirculations progressed further north. Downstream of the Yermak Plateau, an offshore current developed above the 3,800 m isobath, fed by waters from the Yermak Plateau tip. East of 18°E, enhanced mesoscale activity from the boundary current injected additional AW basin‐ward, further contributing to the offshore circulation. A recurrent anticyclonic circulation developed in the Sofia Deep, which also occasionally fed the western part of the offshore flow. The intensification of the circulation coincided with an overall warming in the upper WNB (0–1,000 m), consistent with the progression of AW. This regional description of the changing circulation provides a background for the interpretation of upcoming observations.
Published: 2021
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50. THE WAVY DRIFTERS AND THEIR ROLE IN OCEAN OBSERVATION

Author: Chumbinho, Rogério, Pinto, José, Silva, Raquel, Rio, Joaquín, Gonçalves, Pedro, Sousa, Alexandre, Pedrera, Félix, Lucas, Marc, Almeida, Nuno, Neta, Ricardo, Rocha, Artur, Gomes, Sara, Lozano, Diego, António, Jorge, MORVAN, Gaël, Bluewise, Instituto Hidrografico (Hidrografico ), DEIMOS Engenharia, SARTI-MAR Research Group Universitat Politècnica de Catalunya, Vilanova i la Geltrú, Instituto de Sistemas e Robótica. Department of Electrical and Computer Engineering, Coimbra, OceanScan Marine Systems and Technologies, Deimos Space, Collecte Localisation Satellites (CLS), Composite Solutions, Instituto de Engenharia de Sistemas e Computadores (INESC), Shom, Ifremer, and EuroGOOS AISBL
Subjects: Ocean currents, [SDE] Environmental Sciences, Lagrangean current meters, [SDE]Environmental Sciences, surface drifters, Sea Surface Temperature, near real-time in situ data, Ocean waves, Ocean observation, data validation
Abstract: The WAVY family of drifters, developed in the EU H2020 project MELOA, range from small drifters, suitable for beach and surf zone studies, to somewhat larger drifters, tailored for coastal and long-term open ocean observations, and consists of five members, namely the WAVYs Basic (WB), Littoral (WL), Ocean (WO), Ocean-plus (WP) and Ocean-Atmo (WA). The main characteristics of all WAVY drifters are their small size and weight, their optimized buoyancy, minimizing the vulnerability to direct wind effect; and the internal mass distribution, that minimizes the pendular motion. Other characteristics, such as wave measurement ability and energy management, will be presented.The WB and WL are currently at TRL 8, having been validated and used in real operational environments in a series of demonstrative use cases; the WOs are currently at TRL6 and undergoing use cases designed to bring them to TRL8.MELOA also developed a suite of user-oriented data and SW products, accessible to anyone, that not only facilitate the interface with the drifters, but also allow easy handling and dissemination of both the raw and processed data acquired by the drifters to central ocean data repositories and even creation or use of custom software., La famille de dériveurs WAVY, développée dans le cadre du projet MELOA de l'UE H2020, va des petits dériveurs, adaptés à l'étude des plages et des zones de surf, aux dériveurs un peu plus grands, adaptés aux observations côtières et océaniques à long terme, et se compose de cinq membres, à savoir les WAVY Basic (WB), Littoral (WL), Ocean (WO), Ocean-plus (WP) et Ocean-Atmo (WA). Les principales caractéristiques de tous les dériveurs WAVY sont leur taille et leur poids réduits, leur flottabilité optimisée, minimisant la vulnérabilité à l'effet direct du vent, et la distribution interne de la masse, qui minimise le mouvement pendulaire. D'autres caractéristiques, telles que la capacité de mesure des vagues et la gestion de l'énergie, seront présentées.Les WB et WL sont actuellement au TRL 8, ayant été validés et utilisés dans des environnements opérationnels réels dans une série de cas d'utilisation démonstratifs ; les WO sont actuellement au TRL 6 et font l'objet de cas d'utilisation conçus pour les amener au TRL 8.MELOA a également développé une suite de données orientées utilisateur et de produits logiciels, accessibles à tous, qui non seulement facilitent l'interface avec les dériveurs, mais permettent également une manipulation et une diffusion aisées des données brutes et traitées acquises par les dériveurs vers des dépôts centraux de données océaniques et même la création ou l'utilisation de logiciels personnalisés.
Published: 2021

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