Author: "Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)" / Topic: 010504 meteorology & atmospheric sciences - Searchworks@Jio Institute Digital Library Search Results

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190 results on '"Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)"'

1. Methods for improving species distribution models in data-poor areas: example of sub-Antarctic benthic species on the Kerguelen Plateau

Author: Alexis Martin, Charlène Guillaumot, Thomas Saucède, Marc Eléaume, Laboratoire de Biologie Marine, Université Libre de Bruxelles [Bruxelles] ( ULB ), Biologie des Organismes et Ecosystèmes Aquatiques ( BOREA ), Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Muséum National d'Histoire Naturelle ( MNHN ) -Institut de Recherche pour le Développement ( IRD ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université des Antilles ( UA ), Institut de Systématique, Evolution, Biodiversité ( ISYEB ), Muséum National d'Histoire Naturelle ( MNHN ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ) -École pratique des hautes études ( EPHE ), Biogéosciences [Dijon] ( BGS ), AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Université de Bourgogne ( UB ) -Centre National de la Recherche Scientifique ( CNRS ), Université libre de Bruxelles (ULB), Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Institut de Systématique, Evolution, Biodiversité (ISYEB ), Muséum national d'Histoire naturelle (MNHN)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Biogéosciences [UMR 6282] [Dijon] (BGS), and Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, 010504 meteorology & atmospheric sciences, Environmental change, Presence-only data, Species distribution, Distribution (economics), Model performance, Historical datasets, Aquatic Science, 01 natural sciences, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, Relevance (information retrieval), 14. Life underwater, Ecology, Evolution, Behavior and Systematics, Reliability (statistics), 0105 earth and related environmental sciences, Ecological niche, Kerguelen Plateau, [ SDE.BE ] Environmental Sciences/Biodiversity and Ecology, Ecology, business.industry, 010604 marine biology & hydrobiology, Environmental resource management, Sampling (statistics), 15. Life on land, [ SDV.EE.ECO ] Life Sciences [q-bio]/Ecology, environment/Ecosystems, Species distribution modeling, Habitat, 13. Climate action, Environmental science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, business
Abstract: 16 pages; International audience; Species distribution models (SDMs) are essential tools to aid conservation biologists in evaluating the combined effects of environmental change and human activities on natural habitats and for the development of relevant conservation plans. However, modeling species distributions over vast and remote regions is often challenging due to poor and heterogeneous data sets, and this raises questions regarding the relevance of the modeling procedures. In recent years, there have been many methodological developments in SDM procedures using virtual species and broad data sets, but few solutions have been proposed to deal with poor or heterogeneous data. In the present work, we address this methodological challenge by studying the performance of different modeling procedures based on 4 real species, using presence-only data compiled from various oceanographic surveys on the Kerguelen Plateau (Southern Ocean). We followed a practical protocol to test for the reliability and performance of the models and to correct for limited and aggregated data, as well as accounting for spatial and temporal sampling biases. Our results show that producing reliable SDMs is feasible as long as the amount and quality of available data allow testing and correcting for these biases. However, we found that SDMs could be corrected for spatial and temporal heterogeneities in only 1 of the 4 species we examined, highlighting the need to consider all potential biases when modeling species distributions. Finally, we show that model reliability and performance also depend on the interaction between the incompleteness of the data and species niches, with the distribution of narrow-niche species being less sensitive to data gaps than species occupying wider niches.
Published: 2018

2. Trophic position increases with thermocline depth in yellowfin and bigeye tuna across the Western and Central Pacific Ocean

Author: Aurore Receveur, Lydie I. E. Couturier, Heidi Pethybridge, Jean-Marie Munaron, Elodie Vourey, Yves Letourneur, Patrick Raimbault, Brittany S. Graham, Tsuguo Otake, Sophie Bonnet, Eric Feunteun, Laura Tremblay-Boyer, Valerie Allain, Anne Lorrain, Petra M. Kuhnert, Christophe E. Menkès, Brian P. V. Hunt, Martine Rodier, Bruno Leroy, Benoit Lebreton, Patrick Houssard, David Point, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Insulaire du Vivant et de l'Environnement (LIVE), Université de la Nouvelle-Calédonie (UNC), Institut de Recherche pour le Développement (IRD), Pacific community (SPC), National Institute of Water and Atmospheric Research [Wellington] (NIWA), Processus de couplage à Petite Echelle, Ecosystèmes et Prédateurs Supérieurs (PEPS), 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 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), CSIRO Marine and Atmosphere Research [Hobart], Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-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 Fédérale Toulouse Midi-Pyrénées-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), University of British Columbia (UBC), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN), Institut de Recherche pour le Développement (IRD [Polynésie]), Ecosystèmes Insulaires Océaniens (UMR 241) (EIO), Université de la Polynésie Française (UPF)-Institut Louis Malardé [Papeete] (ILM), Institut de Recherche pour le Développement (IRD)-Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Station marine Dinard, Centre National de la Recherche Scientifique (CNRS), Data61 [Canberra] (CSIRO), Australian National University (ANU)-Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), The University of Tokyo (UTokyo), GOPS HISPANIC, PACIMER, the Pacific Fund VACOPA project, Government of New Caledonia, BIOPELAGOS project funded by the European Union BEST 2.0 Programme, ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), Laboratoire des Sciences de l'Environnement Marin (LEMAR) ( LEMAR ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Brest ( UBO ) -Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ) -Institut Universitaire Européen de la Mer ( IUEM ), Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ), Laboratoire Insulaire du Vivant et de l'Environnement ( LIVE ), Université de la Nouvelle-Calédonie, Secretariat of the Pacific Community ( Secretariat of the Pacific Community ), Secretariat of the Pacific Community, National Institute of Water and Atmospheric Research [Wellington] ( NIWA ), Processus de couplage à Petite Echelle, Ecosystèmes et Prédateurs Supérieurs ( PEPS ), 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 ), CISRO Oceans and Atmosphere, Géosciences Environnement Toulouse ( GET ), Institut de Recherche pour le Développement ( IRD ) -Université Paul Sabatier - Toulouse 3 ( UPS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), University of British Columbia ( UBC ), Institut méditerranéen d'océanologie ( MIO ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Toulon ( UTLN ) -Aix Marseille Université ( AMU ) -Institut de Recherche pour le Développement ( IRD ), Institut de Recherche pour le Développement ( IRD [Polynésie] ), Ecosystèmes Insulaires Océaniens (UMR 241) ( EIO ), Institut de Recherche pour le Développement ( IRD ) -Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ) -Institut Louis Malardé [Papeete] ( ILM ), Institut de Recherche pour le Développement ( IRD ) -Université de la Polynésie Française ( UPF ), Biologie des Organismes et Ecosystèmes Aquatiques ( BOREA ), Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Muséum National d'Histoire Naturelle ( MNHN ) -Institut de Recherche pour le Développement ( IRD ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université des Antilles ( UA ), Centre National de la Recherche Scientifique ( CNRS ), LIttoral ENvironnement et Sociétés - UMR 7266 ( LIENSs ), Université de La Rochelle ( ULR ) -Centre National de la Recherche Scientifique ( CNRS ), The University of Tokyo, ANR-10-LABX-0019/10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean ( 2010 ), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-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)), 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), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de la Polynésie Française (UPF)-Institut Louis Malardé [Papeete] (ILM), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Centre De Recherche et d'Enseignement sur les Systèmes Côtiers (CRESCO), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire Européen de la Mer (IUEM), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)
Subjects: 0106 biological sciences, Delta, Yellowfin tuna, 010504 meteorology & atmospheric sciences, Mesopelagic zone, Depth of the 20°C isotherm, Bigeye tuna, Aquatic Science, 01 natural sciences, [ SDV.EE ] Life Sciences [q-bio]/Ecology, environment, Isoscapes Bigeye tuna, Compound-specific isotope analysis, 14. Life underwater, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Trophic level, [SDV.EE]Life Sciences [q-bio]/Ecology, environment, POM, biology, Depth of the 20 degrees C isotherm, 010604 marine biology & hydrobiology, Nitrogen isotopes, ACL, Biochemical markers, food and beverages, Geology, biology.organism_classification, Food web, Amino acid, Fishery, Oceanography, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Tuna, Thermocline, human activities
Abstract: International audience; Estimates of trophic position are used to validate ecosystem models and understand food web structure. A consumer's trophic position can be estimated by the stable nitrogen isotope values (delta N-15) of its tissue, once the baseline isotopic variability has been accounted for. Our study established the first data-driven baseline delta N-15 isoscape for the Western and Central Pacific Ocean using particulate organic matter. Bulk delta N-15 analysis on 1039 muscle tissue of bigeye and yellowfin tuna were conducted together with amino acid compound-specific delta N-15 analysis (AA-CSIA) on a subset of 21 samples. Both particulate organic matter and tuna bulk delta N-15 values varied by more than 10 parts per thousand across the study area. Fine-scaled trophic position maps were constructed and revealed higher tuna trophic position (by similar to 1) in the southern latitudes compared to the equator. AA-CSIA confirmed these spatial patterns for bigeye and, to a lesser extent, yellowfin tuna. Using generalized additive models, spatial variations of tuna trophic positions were mainly related to the depth of the 20 degrees C isotherm, a proxy for the thermocline behavior, with higher tuna trophic position estimates at greater thermocline depths. We hypothesized that a deeper thermocline would increase tuna vertical habitat and access to mesopelagic prey of higher trophic position. Archival tagging data further suggested that the vertical habitat of bigeye tuna was deeper in the southern latitudes than at the equator. These results suggest the importance of thermocline depth in influencing tropical tuna diet, which affects their vulnerability to fisheries, and may be altered by climate change.
Published: 2017

3. Benthic and fish aggregation inside an offshore wind farm: Which effects on the trophic web functioning?

Author: Aurore Raoux, Géraldine Lassalle, François Le Loc'h, Camille Le Guen, Nathalie Niquil, Jean-Philippe Pezy, Dan Wilhelmsson, Steven Degraer, Jean-Claude Dauvin, Karine Grangeré, Matilda Haraldsson, Bruno Ernande, Samuele Tecchio, Marie Cachera, Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Sorbonne Université (SU)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut de Recherche pour le Développement (IRD), Morphodynamique Continentale et Côtière (M2C), Centre National de la Recherche Scientifique (CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Ecosystèmes aquatiques et changements globaux (UR EABX), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Royal Belgian Institute of Natural Sciences (RBINS), The Royal Swedish Academy of Sciences, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), IFREMER Laboratoire Ressources Halieutiques (IFREMER Laboratoire Ressources Halieutiques), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ressources halieutiques Manche Mer du nord, IFREMER Centre Manche Mer du Nord, (HMMN), Institut de Recherche pour le Développement (IRD), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ressources halieutiques Boulogne sur mer (LRHBL), Halieutique Manche Mer du Nord (HMMN), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Biologie des Organismes et Ecosystèmes Aquatiques ( BOREA ), Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Muséum National d'Histoire Naturelle ( MNHN ) -Institut de Recherche pour le Développement ( IRD ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université des Antilles ( UA ), Morphodynamique Continentale et Côtière ( M2C ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Rouen Normandie ( UNIROUEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ), Ecosystèmes aquatiques et changements globaux ( UR EABX ), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture ( IRSTEA ), Royal Belgian Institute of Natural Sciences ( RBINS ), Laboratoire des Sciences de l'Environnement Marin (LEMAR) ( LEMAR ), Institut de Recherche pour le Développement ( IRD ) -Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ) -Université de Brest ( UBO ) -Institut Universitaire Européen de la Mer ( IUEM ), Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ), IFREMER Laboratoire Ressources Halieutiques ( IFREMER Laboratoire Ressources Halieutiques ), Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ), Institut Universitaire Européen de la Mer (IUEM), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)
Subjects: 0106 biological sciences, Reef effect, 010504 meteorology & atmospheric sciences, General Decision Sciences, 01 natural sciences, [ SDE.IE ] Environmental Sciences/Environmental Engineering, Wind farm, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, Ecosystem model, Ecosystem-based approach, EcoSim, Ecosystem, 14. Life underwater, Ecology, Evolution, Behavior and Systematics, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Trophic level, Biomass (ecology), [ SDU.STU.OC ] Sciences of the Universe [physics]/Earth Sciences/Oceanography, Ecology, [SDE.IE]Environmental Sciences/Environmental Engineering, 010604 marine biology & hydrobiology, ACL, 15. Life on land, Marine renewable energies, Food web, [ SDV.EE.ECO ] Life Sciences [q-bio]/Ecology, environment/Ecosystems, Fishery, Offshore wind power, 13. Climate action, Benthic zone, Ecopath with Ecosim, Environmental science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract: International audience; As part of the energy transition, the French government is planning the construction of three offshore wind farms in Normandy (Bay of Seine and eastern part of the English Channel, northwestern France) in the next years. These offshore wind farms will be integrated into an ecosystem already facing multiple anthropogenic disturbances such as maritime transport, fisheries, oyster and mussel farming, and sediment dredging. Currently no integrated, ecosystem-based study on the effects of the construction and exploitation of offshore wind farms exists, where biological approaches generally focused on the conservation of some valuable species or groups of species. Complementary trophic web modelling tools were applied to the Bay of Seine ecosystem (to the 50 km 2 area covered by the wind farm) to analyse the potential impacts of benthos and fish aggregation caused by the introduction of additional hard substrates from the piles and the turbine scour protections. An Ecopath ecosystem model composed of 37 compartments, from phytoplankton to seabirds, was built to describe the situation " before " the construction of the wind farm. Then, an Ecosim projection over 30 years was performed after increasing the biomass of targeted benthic and fish compartments. Ecological Network Analysis (ENA) indices were calculated for the two periods, " before " and " after " , to compare network functioning and the overall structural properties of the food web. Our main results showed (1) that the total ecosystem activity, the overall system omnivory (proportion of generalist feeders), and the recycling increased after the construction of the wind farm; (2) that higher trophic levels such as piscivorous fish species, marine mammals, and seabirds responded positively to the aggregation of biomass on piles and turbine scour protections; and (3) a change in key-stone groups after the construction towards more structuring and dominant compartments. Nonetheless, these changes could be considered as limited impacts of the wind farm installation on this coastal trophic web structure and functioning.
Published: 2017

4. Evaluating ecosystem-level anthropogenic impacts in a stressed transitional environment: The case of the Seine estuary

Author: Marie Cachera, Nathalie Niquil, Justine Lequesne, Valérie Girardin, Jean-Claude Dauvin, Armonie Tous Rius, Aurore Raoux, Géraldine Lassalle, Samuele Tecchio, Philippe Riou, Jérémy Lobry, Aurélie Chaalali, Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Sorbonne Université (SU)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut de Recherche pour le Développement (IRD), Morphodynamique Continentale et Côtière (M2C), Centre National de la Recherche Scientifique (CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Laboratoire de Mathématiques Nicolas Oresme (LMNO), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Environnement et Ressources de Normandie, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Institut Français de Recherche pour l'Exploitation de la Mer - Atlantique (IFREMER Atlantique), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Ecosystèmes aquatiques et changements globaux (UR EABX), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Environnement Ressources de Normandie (LERN), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Biologie des Organismes et Ecosystèmes Aquatiques ( BOREA ), Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Muséum National d'Histoire Naturelle ( MNHN ) -Institut de Recherche pour le Développement ( IRD ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université des Antilles ( UA ), Morphodynamique Continentale et Côtière ( M2C ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Rouen Normandie ( UNIROUEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ), Laboratoire de Mathématiques Nicolas Oresme ( LMNO ), Normandie Université ( NU ) -Normandie Université ( NU ) -Centre National de la Recherche Scientifique ( CNRS ), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture ( IRSTEA ), Laboratoire des Sciences de l'Environnement Marin (LEMAR) ( LEMAR ), Institut de Recherche pour le Développement ( IRD ) -Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ) -Université de Brest ( UBO ) -Institut Universitaire Européen de la Mer ( IUEM ), Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ), and Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER )
Subjects: 0106 biological sciences, 010504 meteorology & atmospheric sciences, Seine estuary, General Decision Sciences, Estuarine ecosystem, Ecological succession, Linear inverse model, 01 natural sciences, E3, media_common.cataloged_instance, Ecosystem, 14. Life underwater, European union, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, media_common, Trophic level, geography, Biomass (ecology), Ecosystem health, [ SDE.BE ] Environmental Sciences/Biodiversity and Ecology, English Channel, geography.geographical_feature_category, Ecology, 010604 marine biology & hydrobiology, ACL, Estuary, 15. Life on land, Food web, 13. Climate action, Environmental science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract: 00000; International audience; During 2002–2005, a new container terminal in the commercial harbour of Le Havre, named “Port2000”, was built on the northern flank of the Seine estuary, northern France. This extension is already known to have modified the estuary current and sediment dynamics, as well as reducing biomass of the suprabenthos assemblage, for the whole downstream part of the system. However, studies on other biotic communities were largely inconclusive, and an ecosystem-wide analysis was still lacking. Here, we performed a before/after study of ecosystem dynamics of the different habitats of the Seine estuary, using a Linear Inverse Modelling technique (LIM-MCMC) to estimate all flows occurring in the food web. Ecological Network Analysis indices were calculated, summarising ecosystem functioning traits and giving indications about the habitat health status. Results showed that the southern flank (FS, Fosse Sud) exhibits all characteristics to be considered as the least stressed habitat of the estuary: system activity and functional specialisation of flows were stable between periods, ecosystem recycling processes and detrital dynamics were also stable; an increase in trophic specialisation (decrease in system omnivory) was the only change confirming a general ecological succession. The northern flank (FN, Fosse Nord), where the actual terminal was built, showed a food web with increased importance of lower trophic levels (increased detritivory and carbon recycling), increased stability and flow efficiency, but possibly regressed to a previous step in ecological succession. In the central navigation channel (CH), patterns of network indices were overall inconclusive and the general image is one of a constantly shifting food web, a condition possibly caused by the year-round dredging activities. The functioning of the Seine estuary – especially of FN and FS – seems to have been modified by the combination of harbour construction and the related mitigation measures. Network indices partially captured this combination of changes and, although not fully operational yet, they are promising tools to comply with the European Union mandate of defining ecosystem health status.
Published: 2016

5. Demersal ichthyofaunal shelf communities from the Dumont d’Urville Sea (East Antarctica)

Author: Guy Duhamel, Dominique Lamy, Martin J. Riddle, Robin J. Beaman, Patrice Pruvost, Agnès Dettai, Romain Causse, Frédéric Busson, Marc Eléaume, Alexandra L. Post, Catherine Ozouf-Costaz, Philippe Koubbi, Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Systématique, adaptation, évolution (SAE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Royal Netherlands Institute for Sea Research (NIOZ), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Geoscience Australia, Australian Antarctic Division (AAD), Australian Government, Department of the Environment and Energy, Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Institut de Systématique, Evolution, Biodiversité (ISYEB ), Muséum national d'Histoire naturelle (MNHN)-École pratique des hautes études (EPHE), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)
Subjects: 0106 biological sciences, 010504 meteorology & atmospheric sciences, [SDV]Life Sciences [q-bio], Earth and Planetary Sciences(all), Notothenioidei, Aquatic Science, 01 natural sciences, Demersal zone, Demersal fish, Dominance (ecology), 14. Life underwater, ComputingMilieux_MISCELLANEOUS, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, Bathydraconidae, biology, Ecology, 010604 marine biology & hydrobiology, East Antarctica, 15. Life on land, biology.organism_classification, Community structure, Oceanography, Habitat, [SDE]Environmental Sciences, General Earth and Planetary Sciences, Nototheniidae, Species richness
Abstract: The RSV Aurora Australis survey allowed the first comprehensive study of the demersal ichthyofaunal environment and of the diversity of the Dumont d’Urville Sea. We observed a high dominance of the Notothenioidei in both the number of species and in integrated abundances. The Nototheniidae was the most abundant family with 44.7% of the total integrated abundance, followed by Bathydraconidae (18.8%). Trematomus eulepidotus was the dominant species with 19.9% of the total individuals catch. Nevertheless, 43 of the 53 species caught could be considered as very rare. The Bathydraconidae was the most diversified family with 11 species caught. The highest integrated abundances of fish were found from 400 to 800 m. Well-structured species communities were observed, with high species richness from 570 to 681 m. The richest zones were located along the basins and along their upper-sides. Statistical analyses indicated large-scale spatial patterns in species composition, with clear differences in fish communities from the continental slopes, the basins and on the shelf. At a finer spatial scale, the current in the George V Basin and iceberg scouring on the banks and their sides tended to create locally heterogeneous small-scale habitats. We suggest that the glacial history and the structured habitats allowed successive colonisations of the seabed by demersal fish.
Published: 2011
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6. Incorporating food-web parameter uncertainty into Ecopath-derived ecological network indicators

Author: Vanessa Guesnet, Kelly A. Kearney, Géraldine Lassalle, Aurélie Chaalali, Nathalie Niquil, Samuele Tecchio, Boutheina Grami, Battle Karimi, Jérémy Lobry, Blanche Saint-Béat, Ecosystèmes aquatiques et changements globaux (UR EABX), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), University of Miami [Coral Gables], LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Centre National de la Recherche Scientifique (CNRS), LIttoral ENvironnement et Sociétés - UMR 7266 (LIENSs), Sorbonne Université (SU)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut de Recherche pour le Développement (IRD), Laboratoire Chrono-environnement - UFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement (UMR 6249) (LCE), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Ecosystèmes aquatiques et changements globaux ( UR EABX ), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture ( IRSTEA ), Environnements et Paléoenvironnements OCéaniques ( EPOC ), Observatoire aquitain des sciences de l'univers ( OASU ), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -École pratique des hautes études ( EPHE ) -Centre National de la Recherche Scientifique ( CNRS ), LIttoral ENvironnement et Sociétés - UMR 7266 ( LIENSs ), Université de La Rochelle ( ULR ) -Centre National de la Recherche Scientifique ( CNRS ), Biologie des Organismes et Ecosystèmes Aquatiques ( BOREA ), Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Muséum National d'Histoire Naturelle ( MNHN ) -Institut de Recherche pour le Développement ( IRD ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université des Antilles ( UA ), Laboratoire Chrono-environnement ( LCE ), and Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC )
Subjects: 0106 biological sciences, 010504 meteorology & atmospheric sciences, Computer science, Parameter uncertainty, Ecosystem models, computer.software_genre, 01 natural sciences, [ SDE ] Environmental Sciences, Set (abstract data type), Robustness (computer science), Statistics, Range (statistics), EcoSim, Sensitivity (control systems), 0105 earth and related environmental sciences, Interpretability, 010604 marine biology & hydrobiology, Ecological Modeling, Ecological network, Comparative studies, Ecopath with Ecosim, [SDE]Environmental Sciences, Network analysis, Data mining, computer
Abstract: [Departement_IRSTEA]Eaux [TR1_IRSTEA]QUASARE; International audience; Ecological network analysis (ENA) provides numerous ecosystem level indices offering a valuable approach to compare and categorize the ecological structure and function of ecosystems. The inclusion of ENA methods in Ecopath with Ecosim (EwE) has insured their continued contribution to ecosystem-based management. In EwE, ENA-derived ecological conclusions are currently based on single values of ENA indices calculated from a unique input flow matrix. Here, we document an easy-to-use routine that allows EwE users to incorporate uncertainty in EwE input data into the calculation of ENA indices. This routine, named ENAtool, is a suite of Matlab functions that performs three main steps: (1) import of an existing Ecopath model and its associated parameter uncertainty values in the form of uncertainty intervals into Matlab; (2) generation of an ensemble of Ecopath models with the same structure as the original, and with parameter values varying based on the prescribed uncertainty limits; and (3) calculation of a set of 13 ENA indices for each ensemble member (one set of flow values) and of summary statistics across the whole ensemble. This novel routine offers the opportunity to calculate ENA indices ranges and confidence intervals, and thus to perform quantitative data analyses. An application of ENAtool on a pre-existing Ecopath model of the Bay of Biscay continental shelf is presented, with a focus on the robustness of previously published ENA-based ecological traits of this ecosystem when the newly introduced uncertainty values are added. We also describe the sensitivity of the ENAtool results to both the number of ensemble members used and to the uncertainty interval set around each input parameter. Ecological conclusions derived from EwE, particularly those regarding the comparison of structural and functional elements for a range of ecosystem types or the assessment of ecosystem properties along gradients of environmental conditions or anthropogenic disturbances, will gain in statistical interpretability.
Published: 2015

7. Tropical extra-tropical thermocline water mass exchanges in the Community Climate Model v.3 Part I: the Atlantic Ocean

Author: Alban Lazar, Amy Solomon, Ilana Wainer, Department of Physical Oceanography, University of São Paulo (USP), Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), NOAA-CIRES Climate Diagnostics Center, Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado [Boulder]-National Oceanic and Atmospheric Administration (NOAA)-University of Colorado [Boulder]-National Oceanic and Atmospheric Administration (NOAA), and Universidade de São Paulo = University of São Paulo (USP)
Subjects: lcsh:GE1-350, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Water mass, 010504 meteorology & atmospheric sciences, 010505 oceanography, North Atlantic Deep Water, lcsh:Geography. Anthropology. Recreation, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Subtropics, 01 natural sciences, Atlantic Equatorial mode, lcsh:G, 13. Climate action, Climatology, Community Climate System Model, Environmental science, Thermohaline circulation, Climate model, 14. Life underwater, Thermocline, lcsh:Environmental sciences, 0105 earth and related environmental sciences
Abstract: The NCAR CCSM numerical coupled model is used to understand the tropical-extra-tropical pathways of thermocline waters in the Atlantic Ocean. Climatological annual mean simulation results from three numerical experiments are analyzed. Two are fully coupled runs with different spatial resolution (T42 and T85) for the atmospheric component. The third numerical experiment is an ocean-only run forced by NCEP winds and fluxes. Results show that the different atmospheric resolutions have a significant impact on the subduction pathways in the Atlantic because of how the wind field is represented. These simulation results also show that the water subducted at the subtropics reaching the EUC is entirely from the South Atlantic. The coupled model ability to simulate the STCs is discussed.
Published: 2006

8. Projection of future climate change conditions using IPCC simulations, neural networks and Bayesian statistics. Part 2: Precipitation mean state and seasonal cycle in South America

Author: Boulanger, Jean-Philippe, Martinez, F., Segura, E.C., 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 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), Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-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), 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)-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)
Subjects: MODELE MATHEMATIQUE, RESEAU NEURONAL, Atmospheric Science, VARIATION SAISONNIERE, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, 0207 environmental engineering, INTELLIGENCE ARTIFICIELLE, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 02 engineering and technology, 01 natural sciences, VARIATION ANNUELLE, CHANGEMENT CLIMATIQUE, MODELE CLIMATIQUE, 020701 environmental engineering, ANALYSE STATISTIQUE, 0105 earth and related environmental sciences
Published: 2006

9. Variability of the Horizontal Velocity Structure in the Upper 1600 m of the Water Column on the Equator at 10°W

Author: Christine Provost, Jonathan M. Lilly, Jean-Luc Mélice, Annie Kartavtseff, Marc D'orgeville, L. Bunge, Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique des océans (LPO), 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), and Institut de Recherche pour le Développement (IRD)
Subjects: 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], 010505 oceanography, Ocean current, Equator, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Forcing (mathematics), Oceanography, Mooring, Geodesy, 01 natural sciences, Current (stream), Current meter, Acoustic Doppler current profiler, Water column, 13. Climate action, Climatology, Geology, 0105 earth and related environmental sciences
Abstract: This paper presents initial results from new velocity observations in the eastern part of the equatorial Atlantic Ocean from a moored current-meter array. During the “EQUALANT” program (1999–2000), a mooring array was deployed around the equator near 10°W that recorded one year of measurements at various depths. Horizontal velocities were obtained in the upper 60 m from an upward-looking acoustic Doppler current profiler (ADCP) and at 13 deeper levels from current meters between 745 and 1525 m. To analyze the quasiperiodic variability observed in these records, a wavelet-based technique was used. Quasiperiodic oscillations having periods between 5 and 100 days were separated into four bands: 5–10, 10–20, 20–40, and 40–100 days. The variability shows (i) a strong seasonality (the first half of the series is dominated by larger periods than the second one) and (ii) a strong dependence with depth (some oscillations are present in the entire water column while others are only present at certain depths). For the oscillations that are present in the entire water column the origin of the forcing can be traced to the surface, while for the others the question of their origin remains open. Phase shifts at different depths generate vertical shears in the horizontal velocity component with relatively short vertical scales. This is especially visible in long-duration events (>100 days) of the zonal velocity component. Comparison with a simultaneous lowered acoustic Doppler current profiler (LADCP) section suggests that some of these flows may be identified with equatorial deep jets. A striking feature is a strong vertical shear lasting about 7 months between 745 and 1000 m. These deep current-meter observations would then imply a few months of duration for the jets in this region.
Published: 2006

10. Wavelet ridge diagnosis of time-varying elliptical signals with application to an oceanic eddy

Author: Jonathan M. Lilly, Jean-Claude Gascard, Earth and Space Research Institute [Seattle] (ESR), Laboratoire d'océanographie dynamique et de climatologie (LODYC), and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 02 engineering and technology, Ellipse, 01 natural sciences, Instantaneous phase, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Wavelet, Control theory, Position (vector), 0202 electrical engineering, electronic engineering, information engineering, Elliptic integral, lcsh:Science, 0105 earth and related environmental sciences, Mathematics, Series (mathematics), [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Mathematical analysis, lcsh:QC801-809, 020206 networking & telecommunications, Ridge (differential geometry), lcsh:QC1-999, lcsh:Geophysics. Cosmic physics, Orbital motion, lcsh:Q, lcsh:Physics
Abstract: A method for diagnosing the physical properties of a time-varying ellipse is presented. This essentially involves extending the notion of instantaneous frequency to the bivariate case. New complications, and possibilities, arise from the fact that there are several meaningful forms in which a time-varying ellipse may be represented. A perturbation analysis valid for the near-circular case clarifies these issues. Diagnosis of the ellipse properties may then be performed using wavelet ridge analysis, and slowly-varying changes in the ellipse structure may be decoupled from the fast orbital motion through the use of elliptic integrals, without the need for additional explicit filtering. The theory is presented in parallel with an application to a position time series of a drifting subsurface float trapped in an oceanic eddy.
Published: 2006

11. Analysis of the mesoscale circulation in the occidental Mediterranean Sea during winter 1999–2000 given by a regional circulation model

Author: Vincent Echevin, Michel Crépon, Flore Mounier, Laurent Mortier, École Nationale Supérieure de Techniques Avancées (ENSTA Paris), Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), 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), 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)-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)
Subjects: 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], 010505 oceanography, Mesoscale meteorology, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Geology, Aquatic Science, 01 natural sciences, Circulation (fluid dynamics), Mediterranean sea, Oceanography, Hydrology (agriculture), 13. Climate action, Climatology, General Circulation Model, Period (geology), Environmental science, Satellite, 14. Life underwater, 0105 earth and related environmental sciences, Downscaling
Abstract: We present a modelling study of the circulation of the North Western Mediterranean Sea done with a high-resolution regional model (1/16°) embedded in a general circulation model of the Mediterranean Sea of lower resolution (1/8°). Focus is given on coastal and near coastal processes, which are the most sensitive for operational oceanography. The models were forced by 6 h atmospheric fluxes. The regional model was validated over the three-month winter period December 1999–February 2000 by comparing its results with literature, in situ and satellite observations. The hydrology and various features of the circulation on the North Western Mediterranean Sea were reproduced acceptably. This experiment highlights that the downscaling system we dealt with can be used to study a large variety of oceanic features occurring in specific oceanic area. However, the quality of the regional model results are strongly dependent on the quality of the initial state and consequently on the general circulation model.
Published: 2005

12. Reducing Climatology Bias in an Ocean–Atmosphere CGCM with Improved Coupling Physics

Author: Erich Roeckner, Gurvan Madec, Sébastien Masson, Jing-Jia Luo, Toshio Yamagata, Frontier Research Center for Global Change (FRCGC), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Max Planck Institute for Meteorology (MPI-M), Max-Planck-Gesellschaft, Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Department of Earth and Planetary Science [Tokyo], The University of Tokyo (UTokyo), Graduate School of Science [Tokyo], and The University of Tokyo (UTokyo)-The University of Tokyo (UTokyo)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, Momentum transfer, Ocean current, 0207 environmental engineering, Wind stress, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 02 engineering and technology, Entrainment (meteorology), 01 natural sciences, Atmosphere, Sea surface temperature, 13. Climate action, Climatology, Environmental science, Climate model, 14. Life underwater, Current (fluid), 020701 environmental engineering, 0105 earth and related environmental sciences
Abstract: The cold tongue in the tropical Pacific extends too far west in most current ocean–atmosphere coupled GCMs (CGCMs). This bias also exists in the relatively high-resolution SINTEX-F CGCM despite its remarkable performance of simulating ENSO variations. In terms of the importance of air–sea interactions to the climatology formation in the tropical Pacific, several sensitivity experiments with improved coupling physics have been performed in order to reduce the cold-tongue bias in CGCMs. By allowing for momentum transfer of the ocean surface current to the atmosphere [full coupled simulation (FCPL)] or merely reducing the wind stress by taking the surface current into account in the bulk formula [semicoupled simulation (semi-CPL)], the warm-pool/cold-tongue structure in the equatorial Pacific is simulated better than that of the control simulation (CTL) in which the movement of the ocean surface is ignored for wind stress calculation. The reduced surface zonal current and vertical entrainment owing to the reduced easterly wind stress tend to produce a warmer sea surface temperature (SST) in the western equatorial Pacific. Consequently, the dry bias there is much reduced. The warming tendency of the SST in the eastern Pacific, however, is largely suppressed by isopycnal diffusion and meridional advection of colder SST from south of the equator due to enhanced coastal upwelling near Peru. The ENSO signal in the western Pacific and its global teleconnection in the North Pacific are simulated more realistically. The approach as adopted in the FCPL run is able to generate a correct zonal SST slope and efficiently reduce the cold-tongue bias in the equatorial Pacific. The surface easterly wind itself in the FCPL run is weakened, reducing the easterly wind stress further. This is related with a weakened zonal Walker cell in the atmospheric boundary layer over the eastern Pacific and a new global angular momentum balance of the atmosphere associated with reduced westerly wind stress over the southern oceans.
Published: 2005

13. Use of a Neurovariational Inversion for Retrieving Oceanic and Atmospheric Constituents from Ocean Color Imagery: A Feasibility Study

Author: Cédric Jamet, Michel Crépon, Sylvie Thiria, Cyril Moulin, Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-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), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), 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), 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: Atmospheric Science, Quadratic cost, 010504 meteorology & atmospheric sciences, Artificial neural network, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, Inverse, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Ocean Engineering, Inversion (meteorology), 01 natural sciences, Synthetic data, 010309 optics, Wavelength, 13. Climate action, Ocean color, 0103 physical sciences, Radiative transfer, Environmental science, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, Remote sensing
Abstract: This paper presents a neurovariational method for inverting satellite ocean-color signals. The method is based on a combination of neural networks and classical variational inversion. The radiative transfer equations are modeled by neural networks whose inputs are the oceanic and atmospheric parameters, and outputs the top of the atmosphere reflectance at several wavelengths. The procedure consists in minimizing a quadratic cost function that is the distance between the satellite-observed reflectance and the computed neural-network reflectance, the control parameters being the oceanic and atmospheric parameters. First, a feasibility experiment using synthetic data is presented to show that chlorophyll-a can be retrieved with an error of 19.7% when the atmospheric parameters are known exactly. Then both atmospheric and oceanic parameters are relaxed. A first guess for the atmospheric parameters was provided by a direct inverse neural network whose inputs are at near-infrared wavelengths. Sensitivity experiments showed that these parameters can be retrieved with an adequate accuracy. An inversion of a composite SeaWiFS image is presented. Optical thickness and chlorophyll-a both give coherent spatial structures when a background term is added to the cost function. Finally, chlorophyll-a retrievals are compared with SeaWiFS product through in situ data. It shows a better estimation of the chlorophyll-a with the neurovariational inversion for the oligotrophic regions.
Published: 2005

14. Observed precipitation in the Paran�-Plata hydrological basin: long-term trends, extreme conditions and ENSO teleconnections

Author: Walter M. Vargas, Florence Lafon, Jean-Philippe Boulanger, Julie Leloup, Matilde Rusticucci, Olga Penalba, Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), 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 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), 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), 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)-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)
Subjects: Atmospheric Science, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Anomaly (natural sciences), 0207 environmental engineering, Drainage basin, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 02 engineering and technology, 15. Life on land, Structural basin, Monsoon, 01 natural sciences, La Niña, Sea surface temperature, 13. Climate action, Climatology, Environmental science, Precipitation, 020701 environmental engineering, 0105 earth and related environmental sciences, Teleconnection
Abstract: The Parana-Plata basin is the second largest hydrological basin in South America and is of great importance for the countries of the region (Argentina, Bolivia, Brazil, Paraguay and Uruguay). The present study focuses on the long-term trends in basin-scale precipitation with special emphasis on the role of distribution changes in extreme large-scale precipitation events and on the characteristics and evolution of ENSO teleconnections over the last 50 years. First, we defined a Parana-Plata basin total precipitation index (PTPI) as the precipitations spatially averaged over the hydrological basin. On interannual time scales, such an index is mainly representative of anomalous monsoon precipitations in the northern part of the basin and large convective precipitation anomalies in the center of the basin (Paraguay-southern Brazil-Uruguay-northern Argentina) typical of the canonical ENSO teleconnection pattern. Our major findings clearly highlight a positive trend in yearly averaged PTPI mainly from the late 1960s to the early 1980s with a strong dependence from month-to-month. The largest precipitation increase is observed from November to May in southern Brazil and Argentina. A close examination of PTPI distributions during the two halves of the period 1950–2001 shows that the changes in the mean state from 1950–1975 to 1976–2001 result from significant changes in each calendar month mean state and in the tails of the PTPI anomaly distributions in May with lesser and weaker large-scale dry events and stronger large-scale wet events. Further studies will be needed to assess whether the observed trend in large-scale extreme precipitation conditions can be related to natural climate variability or anthropogenic activities and whether it is associated to changes in local/regional extreme events. The stronger wet conditions in different months seem to be associated to changes in ENSO characteristics (amplitude, propagation, spatial structure, ...) since the 1982–1983 El Nino. Indeed, spatial ENSO teleconnections (stronger in November and April–May) have greatly evolved from 1950–1975 to 1976–2001. Moreover, we demonstrate that there is a strong modulation and displacement of the teleconnection patterns from one event to another, impeding the definition of robust statistical relationship between ENSO and precipitation in the Parana-Plata basin (except maybe over a very limited area near the common border between Paraguay, Argentina and Brazil). Finally, the non-antisymmetrical patterns of precipitation between El Nino and La Nina conditions and the non-linear relationship between precipitation and either Nino3.4 or Nino1+2 sea surface temperature indices show that linear statistical forecast systems are actually of very limited use for impact predictions on society on a local or regional scale.
Published: 2005

15. Incorporating State-Dependent Temperature–Salinity Constraints in the Background Error Covariance of Variational Ocean Data Assimilation

Author: Jérôme Vialard, Anthony T. Weaver, Sophie Ricci, Philippe Rogel, Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), 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), CERFACS, Laboratoire d'océanographie dynamique et de climatologie (LODYC), and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheric Science, Multivariate statistics, 010504 meteorology & atmospheric sciences, Global temperature, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, Ocean current, 0207 environmental engineering, Univariate, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 02 engineering and technology, Ocean general circulation model, Covariance, Atmospheric sciences, 01 natural sciences, Salinity, Data assimilation, 13. Climate action, Climatology, 14. Life underwater, 020701 environmental engineering, 0105 earth and related environmental sciences, Mathematics
Abstract: Several studies have illustrated how the univariate assimilation of temperature data can have a detrimental effect on the ocean-state variables (salinity, currents, etc.) not directly constrained by the data. In this paper, the authors describe how the salinity adjustment method proposed by Troccoli and Haines can be included as a multivariate temperature–salinity (T–S) constraint within a background-error covariance model for variational data assimilation. The method is applied to a three-dimensional variational assimilation (3DVAR) system for a tropical Pacific version of the Océan Parallélisé (OPA) ocean general circulation model. An identical twin experiment is presented first to illustrate how the method is effective in reconstructing a density profile using only temperature observations from that profile. The 3DVAR system is then cycled over the period 1993–98 using in situ temperature data from the Global Temperature and Salinity Pilot Programme. Relative to a univariate (T) 3DVAR, the multivariate (T, S) 3DVAR significantly improves the salinity mean state. A comparison with salinity data that are not assimilated is also presented. The fit to these observations is improved when the T–S constraint is applied. The salinity correction leads to a better preservation of the salinity structure and avoids the development of spurious geostrophic currents that were evident in the univariate analysis. The currents at the surface and below the core of the undercurrent are also improved. Examination of the heat budget highlights how the temperature increment must compensate for a perpetual degradation of the temperature field by abnormally strong advection in the univariate experiment. When the T–S constraint is applied, this spurious advection is reduced and the mean temperature increment is decreased. Examination of the salt budget shows that spurious advection is also the main cause of the upper-ocean freshening. When the T–S constraint is applied, the salinity structure is improved allowing for a better representation of the advection term and better preservation of the salt content in the upper ocean. The T–S constraint does not correct for all problems linked to data assimilation: vertical mixing is still too strong, and the surface salinity state and currents still have substantial errors. Improvements can be expected by including additional constraints in the background error covariances and by assimilating salinity data.
Published: 2005

16. Life at cold seeps: a synthesis of biogeochemical and ecological data from Kazan mud volcano, eastern Mediterranean Sea

Author: Werne, J.P., Haese, R.R., Zitter, T.A.C., Aloisi, G, Bouloubassi, I., Heijs, S., Fiala-Medioni, A., Pancost, R.D., Sinninghe Damste, J.S., de Lange, G., Forney, L.J., Gottschal, J.C., Foucher, J.-P., Mascle, J., Woodside, J.M., MEDINAUT and MEDINETH, Party, Sedimentology, Department of Marine Biogeochemistry and Toxicology, Royal Netherlands Institute for Sea Research (NIOZ), Department of Earth Sciences - Geochemistry [Utrecht], Utrecht University [Utrecht], Department of Sedimentology and Marine Geology Faculty of Earth and Life Sciences, Free University of Amsterdam, Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de biogéochimie et chimie marines (LBCM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Department of Microbiology, University of Groningen [Groningen]-Center for Ecological and Evolutionary Studies, Laboratoire d'océanographie biologique de Banyuls (LOBB), Observatoire océanologique de Banyuls (OOB), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Center for Marine Earth Sciences [Amsterdam], Géosciences Marines (GM), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: GAS HYDRATE, Biogeochemical cycle, 010504 meteorology & atmospheric sciences, Aardwetenschappen, MARINE-SEDIMENTS, Clathrate hydrate, MID-ATLANTIC RIDGE, Geochemistry, FLUID-FLOW, 010502 geochemistry & geophysics, 01 natural sciences, Methane, chemistry.chemical_compound, mud volcano, biogeochemistry, Geochemistry and Petrology, cold seep fauna, ARCHAEA, SDG 14 - Life Below Water, 14. Life underwater, ComputingMilieux_MISCELLANEOUS, AUTHIGENIC CARBONATES, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, IN-SITU, microbiology, Geology, Authigenic, anaerobic oxidation of methane, 15. Life on land, Cold seep, Petroleum seep, Oceanography, chemistry, 13. Climate action, Anaerobic oxidation of methane, ALEUTIAN SUBDUCTION ZONE, ANAEROBIC METHANE OXIDATION, LIPIDS, Mud volcano
Abstract: Recent field observations have identified the widespread occurrence of fluid seepage through the eastern Mediterranean Sea floor in association with mud volcanism or along deep faults. Gas hydrates and methane seeps are frequently found in cold seep areas and were anticipated targets of the MEDINAUT/MEDINETH initiatives. The study presented herein has utilized a multi-disciplinary approach incorporating observations and sampling of visually selected sites by the manned submersible Nautile and by ship-based sediment coring and geophysical surveys. The study focuses on the biogeochemical and ecological processes and conditions related to methane seepage, especially the anaerobic oxidation of methane (AOM), associated with ascending fluids on Kazan mud volcano in the eastern Mediterranean. Sampling of adjacent box cores for studies on the microbiology, biomarkers, pore water and solid phase geochemistry allowed us to integrate different biogeochemical data within a spatially highly heterogeneous system. Geophysical results clearly indicate the spatial heterogeneity of mud volcano environments. Results from pore water geochemistry and modeling efforts indicate that the rate of AOM is similar to 6 mol m(-2) year(-1), which is lower than at active seep sites associated with conditions of focused flow, but greater than diffusion-dominated sites. Furthermore, under the non-focused flow conditions at Kazan mud volcano advective flow velocities are of the order of a few centimeters per year and gas hydrate formation is predicted to occur at a sediment depth of about 2 m and below. The methane flux through these sediments supports a large and diverse community of micro- and macrobiota, as demonstrated by carbon isotopic measurements on bulk organic matter, authigenic carbonates, specific biomarker compounds, and macrofaunal tissues. Because the AOM community appears to be able to completely oxidize methane at the rate it is seeping through the sediments, ultimate sinks for methane in this environment are authigenic carbonates and biomass. Significant differences in organic geochemical data between this site and those of other cold seep environments, even within the eastern Mediterranean mud volcanoes, indicate that the microbiological communities carrying out AOM varies depending on specific conditions such as methane flux and salinity. (C) 2004 Elsevier B.V. All rights reserved.
Published: 2004

17. An intercomparison between the surface heat flux feedback in five coupled models, COADS and the NCEP reanalysis

Author: Michael Botzet, Rowan Sutton, Andrea F. Carril, Laurent Terray, Helge Drange, A. Pardaens, Claude Frankignoul, Elodie Kestenare, Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS), and CERFACS
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, Tropical Atlantic Variability, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, Northern Hemisphere, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Atmospheric model, Tropical Atlantic, 010502 geochemistry & geophysics, 01 natural sciences, Physics::Geophysics, Sea surface temperature, Heat flux, 13. Climate action, Climatology, Middle latitudes, Environmental science, Climate model, 14. Life underwater, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences
Abstract: The surface heat flux feedback is estimated in the Atlantic and the extra-tropical Indo-Pacific, using monthly heat flux and sea surface temperature anomaly data from control simulations with five global climate models, and it is compared to estimates derived from COADS and the NCEP reanalysis. In all data sets, the heat flux feedback is negative nearly everywhere and damps the sea surface temperature anomalies. At extratropical latitudes, it is strongly dominated by the turbulent fluxes. The radiative feedback can be positive or negative, depending on location and season, but it remains small, except in some models in the tropical Atlantic. The negative heat flux feedback is strong in the mid-latitude storm tracks, exceeding 40 W m-2 K-1 at place, but in the Northern Hemisphere it is substantially underestimated in several models. The negative feedback weakens at high latitudes, although the models do not reproduce the weak positive feedback found in NCEP in the northern North Atlantic. The main differences are found in the tropical Atlantic where the heat flux feedback is weakly negative in some models , as in the observations, and strongly negative in others where it can exceed 30 W m-2 K-1 at large scales, in part because of a strong contribution of the radiative fluxes, in particular during spring. A comparison between models with similar atmospheric or oceanic components suggests that the atmospheric model is primarily responsible for the heat flux feedback differences at extra-tropical latitudes. In the tropical Atlantic, the ocean behavior plays an equal role. The differences in heat flux feedback in the tropical Atlantic are reflected in the sea surface temperature anomaly persistence, which is too small in models where the heat flux damping is large. A good representation of the heat flux feedback is thus required to simulate climate variability realistically. acceptedVersion
Published: 2004

18. Variability of the partial pressure of CO2 on diel to annual time scales in the Northwestern Mediterranean Sea

Author: Miléna Bégovic, Liliane Merlivat, Claire Copin-Montégut, Laboratoire d'océanographie de Villefranche (LOV), 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), Laboratoire d'océanographie dynamique et de climatologie (LODYC), and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, Mediterranean climate, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Buoy, 010604 marine biology & hydrobiology, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], General Chemistry, Oceanography, 01 natural sciences, Sink (geography), Mediterranean sea, 13. Climate action, Environmental Chemistry, Environmental science, Spatial variability, 14. Life underwater, Transect, Diel vertical migration, Surface water, 0105 earth and related environmental sciences, Water Science and Technology
Abstract: Continuous underway measurements of the partial pressure of CO2 in surface water were performed on a monthly basis from February 1998 to February 2000 along a transect between Nice and the Dyfamed site located in the open central zone of the Ligurian–Provencal basin of the Northwestern Mediterranean. Hourly measurements of pCO2 were also performed with Carioca buoys moored at the Dyfamed site from February to May 1999 and in October 1999. The shipboard measurements allowed the spatial variability of pCO2 from the coastal area to the central part of the basin over diel and annual time scales to be evaluated. The variability over scales of a few hours or a few kilometers was highest in winter in the central part of the basin, when the surface temperature was close to 13 °C. During this period, the pCO2 variations were correlated to salinity and variations in pCO2 of up to 70 μatm over a period of 16 h were observed. This winter variability can be explained by vertical mixing. The annual variations in pCO2 range from 300 to 420 μatm at the Dyfamed site and from 315 to 450 μatm in the Ligurian current. They are mostly due to temperature variations (13 to 26 °C), but the effect of temperature is counterbalanced mainly by biological production in spring and by vertical mixing in autumn. The results obtained at the Dyfamed site confirm those obtained by Hood and Merlivat [J. Mar. Res. 59 (2001) 113] with a Carioca buoy, but show interannual variability. Over short time scales, the variations of pCO2 normalized to 13 °C are linked to the wind speed variations or to the chlorophyll fluorescence during periods of high biological productivity. As well in the central part of the basin as in the coastal Ligurian current, this region of the Mediterranean Sea is a medium sink for the atmospheric CO2.
Published: 2004

19. The dynamics of the Sicily Strait: a comprehensive study from observations and models

Author: Laurent Mortier, Michel Crépon, Karine Béranger, L. Gervasio, M. Astraldi, Gian Pietro Gasparini, Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), 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 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), Istituto per lo studio dell'Oceanografia Fisica, Consiglio Nazionale delle Ricerche [Roma] (CNR), and National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR)
Subjects: 0106 biological sciences, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, 010604 marine biology & hydrobiology, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Context (language use), Ocean general circulation model, Oceanography, 01 natural sciences, language.human_language, Mediterranean sea, Sill, Anticyclone, Ocean gyre, Climatology, language, Upwelling, 14. Life underwater, Sicilian, Geology, 0105 earth and related environmental sciences
Abstract: The dynamics of the Sicily Strait are investigated in a comprehensive study using recent in situ observations, Ocean General Circulation Model (OGCM) simulations and process model results. In particular, results of a very high-resolution Mediterranean model (MED16) developed in the context of the Mercator project are described. The circulation in the Sicily Strait can be described as a two-layer exchange of Atlantic Water (AW) and Eastern Mediterranean Outflow Water (EOW). The Algerian Current brings AW (the upper layer) eastwards and splits into two branches at the entrance to the Sicily Strait, one flowing to the Tyrrhenian Sea, the other into the Sicily Strait. The later is composed of two streams, referred to as the Atlantic Ionian Stream (AIS) and the Atlantic Tunisian Current (ATC). In winter, the ATC signature is more pronounced. In summer, the AIS is associated with a number of well-known semi-permanent features including the intermittent northward extension of the AIS (called NAIS) at the Ionian shelf break, which seems to be driven by the surface density contrast between waters of the Sicilian and the Ionian basins. New intermittent patterns are shown by the MED16 simulations, for example an anticyclonic eddy (called MCA) south of the Malta Channel and an anticyclonic gyre associated to the NAIS (called NAISA). Upwelling is well developed in August, with temperature lower than 24°C along the western and southern coasts of Sicily. The seasonal transport of the AW through the strait has a maximum value (1.4 Sv ) in winter, and a minimum value at the end of summer (0.8 Sv ) . In the lower layer, at the exit of the Sicily Strait, the EOW, mainly composed of Levantine Intermediate Water (LIW), outflows into the Tyrrhenian Sea and veers to the right. Then, as well known, the LIW flows along the northern coast of Sicily before reaching the Sardinia Channel. A new LIW path from the Sicily Strait towards the Sardinia Channel is shown by the MED16 model, and is due to intermediate eddy shedding at the exit of the Sicily Strait. The topography of the sill in the Sicily Strait plays a major role in the circulation. A combination of barotropic/baroclinic double Kelvin waves on both side of the sill provides a mechanism, for splitting the Algerian Current.
Published: 2004

20. DMS atmospheric concentrations and sulphate aerosol indirect radiative forcing: a sensitivity study to the DMS source representation and oxidation

Author: Olivier Boucher, Mark Lawrence, Cyril Moulin, M. S. Reddy, Jean Sciare, Chandra Venkataraman, R. von Kuhlmann, Maï Pham, Laurent Bopp, Emmanuel Cosme, Sauveur Belviso, Olivier Aumont, Laboratoire d’Optique Atmosphérique - UMR 8518 (LOA), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lille-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), Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Écoulements Géophysiques et Industriels [Grenoble] (LEGI), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Chemistry (MPIC), Max-Planck-Gesellschaft, Max-Planck-Institut für Chemie (MPIC), Service d'aéronomie (SA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-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 for Environmental Science and Engineering [Bombay] (CESE), Indian Institute of Technology Bombay (IIT Bombay), Correspondant HAL 2, LEGI, 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), Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Recherche pour le Développement (IRD), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble [1985-2015] (OSUG [1985-2015]), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology [2007-2019] (Grenoble INP [2007-2019])-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology [2007-2019] (Grenoble INP [2007-2019])-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), ICOS-RAMCES (ICOS-RAMCES), 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)-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 des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Chimie Atmosphérique Expérimentale (CAE), 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), 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)-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)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Lille, Université Paris-Saclay-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), and Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheric Science, Seasonal-Variation, 010504 meteorology & atmospheric sciences, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], [SPI.MECA.MEFL] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph], 010501 environmental sciences, Atmospheric sciences, 01 natural sciences, [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph], Atmosphere, lcsh:Chemistry, chemistry.chemical_compound, [PHYS.MECA.MEFL] Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], 14. Life underwater, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], Sulfate, 0105 earth and related environmental sciences, Dimethyl Sulfide, Climate Model, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Sulfur cycle, Radiative forcing, Sulfur Cycle, Global Distributions, lcsh:QC1-999, Aerosol, Bromine Oxide, chemistry, lcsh:QD1-999, 13. Climate action, Cloud albedo, Environmental science, Dimethyl sulfide, Climate model, Amsterdam-Island, lcsh:Physics, Southern Indian-Ocean, Cloud Albedo
Abstract: PAR00002853; International audience; The global sulphur cycle has been simulated using a general circulation model with a focus on the source and oxidation of atmospheric dimethylsulphide (DMS). The sensitivity of atmospheric DMS to the oceanic DMS climatology, the parameterisation of the sea-air transfer and to the oxidant fields have been studied. The importance of additional oxidation pathways (by O3 in the gas- and aqueous-phases and by BrO in the gas phase) not incorporated in global models has also been evaluated. While three different climatologies of the oceanic DMS concentration produce rather similar global DMS fluxes to the atmosphere at 24-27 Tg S yr -1, there are large differences in the spatial and seasonal distribution. The relative contributions of OH and NO3 radicals to DMS oxidation depends critically on which oxidant fields are prescribed in the model. Oxidation by O3 appears to be significant at high latitudes in both hemispheres. Oxidation by BrO could be significant even for BrO concentrations at sub-pptv levels in the marine boundary layer. The impact of such refinements on the DMS chemistry onto the indirect radiative forcing by anthropogenic sulphate aerosols is also discussed.
Published: 2003

21. Evaluation of ocean model ventilation with CFC-11: comparison of 13 global ocean models

Author: Jean-Claude Dutay, John Marshall, Gurvan Madec, Akio Ishida, J.-M. Campin, Anne Mouchet, Ken Caldeira, Richard D. Slater, Yongqi Gao, Andrew Yool, Yasuhiro Yamanaka, John L. Bullister, Helge Drange, Gian-Kasper Plattner, Michael J. Follows, Jorge L. Sarmiento, Richard J. Matear, Scott C. Doney, Marie-France Weirig, Ernst Maier-Reimer, Raymond G. Najjar, Keith Lindsay, Patrick Monfray, Fortunat Joos, Matthew W. Hecht, Nicolas Gruber, I. Totterdell, Reiner Schlitzer, James C. Orr, 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), Modélisation du climat (CLIM), 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)-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), NOAA Pacific Marine Environmental Laboratory [Seattle] (PMEL), National Oceanic and Atmospheric Administration (NOAA), National Center for Atmospheric Research [Boulder] (NCAR), Pennsylvania State University (Penn State), Penn State System, Lawrence Livermore National Laboratory (LLNL), Institut d'Astronomie et de Géophysique Georges Lemaître (UCL-ASTR), Université Catholique de Louvain = Catholic University of Louvain (UCL), Nansen Environmental and Remote Sensing Center [Bergen] (NERSC), Massachusetts Institute of Technology (MIT), Atmospheric and Oceanic Sciences Program [Princeton] (AOS Program), NOAA Geophysical Fluid Dynamics Laboratory (GFDL), National Oceanic and Atmospheric Administration (NOAA)-National Oceanic and Atmospheric Administration (NOAA)-Princeton University, Research Institute for Global Change (RIGC), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Climate and Environmental Physics [Bern] (CEP), Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE)-Universität Bern [Bern] (UNIBE), Oeschger Centre for Climate Change Research (OCCR), University of Bern, Climate and Global Dynamics Division [Boulder] (CGD), Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Meteorology (MPI-M), Max-Planck-Gesellschaft, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Astrophysics and Geophysics Institute [Liège], Université de Liège, Institute of Applied Physics [Bern] (IAP), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), National Oceanography Centre [Southampton] (NOC), University of Southampton, 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), 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)-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), and Universität Bern [Bern]-Universität Bern [Bern]
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Ocean ventilation, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Physical oceanography, Oceanography, 01 natural sciences, Bottom water, Models, Ocean gyre, Computer Science (miscellaneous), 14. Life underwater, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, 010505 oceanography, North Atlantic Deep Water, Geotechnical Engineering and Engineering Geology, Ocean dynamics, Antarctic Bottom Water, CFC, 13. Climate action, Climatology, Thermohaline circulation, Ocean heat content, Transient tracers, Geology
Abstract: International audience; We compared the 13 models participating in the Ocean Carbon Model Intercomparison Project (OCMIP) with regards to their skill in matching observed distributions of CFC-11. This analysis characterizes the abilities of these models to ventilate the ocean on timescales relevant for anthropogenic CO2 uptake. We found a large range in the modeled global inventory (±30%), mainly due to differences in ventilation from the high latitudes. In the Southern Ocean, models differ particularly in the longitudinal distribution of the CFC uptake in the intermediate water, whereas the latitudinal distribution is mainly controlled by the subgrid-scale parameterization. Models with isopycnal diffusion and eddy-induced velocity parameterization produce more realistic intermediate water ventilation. Deep and bottom water ventilation also varies substantially between the models. Models coupled to a sea-ice model systematically provide more realistic AABW formation source region; however these same models also largely overestimate AABW ventilation if no specific parameterization of brine rejection during sea-ice formation is included. In the North Pacific Ocean, all models exhibit a systematic large underestimation of the CFC uptake in the thermocline of the subtropical gyre, while no systematic difference toward the observations is found in the subpolar gyre. In the North Atlantic Ocean, the CFC uptake is globally underestimated in subsurface. In the deep ocean, all but the adjoint model, failed to produce the two recently ventilated branches observed in the North Atlantic Deep Water (NADW). Furthermore, simulated transport in the Deep Western Boundary Current (DWBC) is too sluggish in all but the isopycnal model, where it is too rapid.
Published: 2002

22. Modeled and observed impacts of the 1997-1998 El Niño on nitrate and new production in the equatorial Pacific

Author: Anne Stoens, Cyril Moulin, Yves Dandonneau, Thierry Delcroix, Jérôme Vialard, Christophe E. Menkès, Pierre-Yves Deschamps, Cécile Dupouy, Marie-Helene Radenac, Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), 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), Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie]), Laboratoire d’Optique Atmosphérique - UMR 8518 (LOA), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), and 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)
Subjects: 0106 biological sciences, Atmospheric Science, Biogeochemical cycle, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Soil Science, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Aquatic Science, Structural basin, Oceanography, 01 natural sciences, Sink (geography), MODELE, chemistry.chemical_compound, Nitrate, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, EL NINO, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, geography, geography.geographical_feature_category, Ecology, DONNEES SATELLITE, PRODUCTION BIOLOGIQUE, 010604 marine biology & hydrobiology, Ocean current, Paleontology, Biogeochemistry, Forestry, New production, CHLOROPHYLLE, VARIATION INTERANNUELLE, Geophysics, chemistry, 13. Climate action, Space and Planetary Science, FACTEUR CLIMATIQUE, PLANCTON, Bloom, NITRATE, IMPACT SUR L'ENVIRONNEMENT
Abstract: The impact of the strong 1997-1998 E1Nifio event on nitrate distribution and new production in the equatorial Pacific is investigated, using a combination of satellite and in situ observations, and an ocean circulation-biogeochemical model. The general circulation model is forced with realistic wind stresses deduced from ERS-1 and ERS-2 scatterometers over the 1993-1998 period. Its outputs are used to drive a biogeochemical model where biology is parameterized as a nitrate sink. We first show that the models capture the essential circulation and biogeochemical equatorial features along with their temporal evolution during the 1997-1998 event, although the modeled variability seems underestimated. In particular, the model fails to reproduce unusual bloom conditions. This is attributed to the simplicity of the biological model. An analysis of the physical mechanisms responsible for the dramatic decrease of the biological equatorial production during E1 Nifio is then proposed. During the growth phase (November 1996 through June 1997), nitrate-poor waters of the western Pacific are advected eastward, and the vertical supply of nitrate is reduced due to nitracline deepening. These processes result in the invasion of the equatorial Pacific by nitrate-poor waters during the mature phase (November 1997 through January 1998). At that time, the central Pacific is nitrate limited and experiences warm pool oligotrophic conditions. As a result, the modeled new production over the equatorial Pacific drops by 40% compared to the mean 1993-1996 values. Then, while E1Nifio conditions are still present at the surface, the nitracline shallows over most of the basin in early 1998. Therefore the strengthening of the trade winds in May 1998 efficiently switches on the nitrate vertical supply over a large part of the equatorial Pacific, leading to a rapid return of high biological production conditions. Strong La Nifia conditions then develop, resulting in a biologically rich tongue extending as far west as 160°E for several months.
Published: 2001

23. Choice of an advection scheme for biogeochemical models

Author: Marina Lévy, Audrey Estublier, Gurvan Madec, Laboratoire d'océanographie dynamique et de climatologie (LODYC), and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Scheme (programming language), Biogeochemical cycle, 010504 meteorology & atmospheric sciences, Meteorology, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], 010505 oceanography, Advection, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Context (language use), 01 natural sciences, Geophysics, General Earth and Planetary Sciences, Environmental science, Applied mathematics, computer, 0105 earth and related environmental sciences, computer.programming_language
Abstract: Five advection schemes are compared and evaluated in the context of biogeochemical modeling. Using three schemes of comparable quality that have been used in recent biogeochemical models, we found that new production estimates vary by as much as 30%. Test experiments are presented that explain the large discrepancies in terms of the different types of numerical errors inherent to each scheme. One scheme is suggested for eddy-resolving models and another one for coarse resolution models.
Published: 2001

24. Mixing in weakly turbulent stably stratified flows

Author: Pascale Bouruet-Aubertot, Chantal Staquet, Laboratoire des Écoulements Géophysiques et Industriels [Grenoble] (LEGI), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), 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 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), 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)-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)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, Stratified flows, Oceanography, 01 natural sciences, Stably stratified flows, [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph], 010305 fluids & plasmas, Physics::Fluid Dynamics, symbols.namesake, Mixing, Geophysical fluid dynamics, 0103 physical sciences, Froude number, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], Computers in Earth Sciences, Stratified flow, Mixing (physics), 0105 earth and related environmental sciences, Physics, Richardson number, Turbulence, Breaking wave, Geology, Mechanics, Classical mechanics, symbols
Abstract: We analyse mixing in three weakly turbulent stably stratified flows, namely low amplitude breaking internal gravity waves, stably stratified homogeneous decaying turbulence and a stably stratified unstable shear layer. We use the method proposed by Winter et al. [J. Fluid Mech. 289 (1995) 115], which provides an exact expression of the diffusive flux of density responsible for mixing. When the three flows have stabilized and organized into quasi-horizontal layers, we show that the diffusion coefficient behaves linearly as a function of a dynamical parameter that characterizes the largest scales of the flow (a Froude number squared or the inverse of a Richardson number) and we provide a simple expression of this linear law.
Published: 2001

25. Short timescale variations of ƒCO2in a North Atlantic warm-core eddy: Results from the Gas-Ex 98 carbon interface ocean atmosphere (CARIOCA) buoy data

Author: E. M. Hood, Liliane Merlivat, Rik Wanninkhof, Laboratoire d'océanographie dynamique et de climatologie (LODYC), and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, Atmospheric Science, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Soil Science, Flux, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Forcing (mathematics), Aquatic Science, Oceanography, 01 natural sciences, Wind speed, Atmosphere, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Ecology, Buoy, 010604 marine biology & hydrobiology, Paleontology, Forestry, Storm, Oceanography: General, Sea surface temperature, Geophysics, 13. Climate action, Space and Planetary Science, Climatology, Environmental science, Upwelling
Abstract: International audience; During a Lagrangian deliberate tracer study in the North Atlantic, the 1998 Gas Exchange Experiment, hourly measurements of wind speed, sea surface temperature, fCO2, and fluorescence were made from two carbon interface ocean atmosphere (CARIOCA) drifting buoys in a warm-core eddy near 46°N and 21.5°W over a period of approximately 20 days. Shipboard measurements of fCO2 near the buoys were used to verify the buoy operation, calibrate the buoy measurements, and assess the performance of the fCO2 sensor. The strong air-sea fCO2 gradient in the eddy and intense atmospheric forcing during the experiment provided ideal conditions for demonstrating the potential of autonomous drift buoy measurements for studies of surface ocean biogeochemistry, where changes of fCO2 were rapid and large. During the experiment a storm occurred with wind speeds reaching as high as 16-17 m s-1, leading to a sharp decrease in sea surface temperature and an increase in fCO2 of ~30 μatm. The magnitude of this sudden change in fCO2 is equal to approximately half of the annual range of fCO2 in this area. The air-sea flux estimate for the ~20 day experiment using the Wanninkhof [1992] gas transfer velocity formulation was -0.012 mol m-2 d-1 and using the Liss and Merlivat [1986] formulation was -0.007 mol m-2 d-1. The storm event, lasting 3-4 days, accounted for ~38% of the flux over this period. Approximately 16 hours after the onset of the storm, there was an increase in surface fluorescence coincident with the initial increase in fCO2. Nitrate measurements made from the ship in the eddy show a sharp peak in surface concentrations ~24 hours after the increase in winds and ~6-8 hours after the increase in surface fluorescence. After the upwelling of the NO3 the fluorescence increases more sharply while the fCO2 decreases, consistent with biological productivity. The surface fluorescence measurements remain higher than prestorm conditions for ~5 days after the NO3 has disappeared.
Published: 2001

26. Warm and cold water routes of an O.G.C.M. thermohaline conveyor belt

Author: Bruno Blanke, Gurvan Madec, Sabrina Speich, Laboratoire d'océanographie dynamique et de climatologie (LODYC), and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Water mass, Throughflow, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], 010505 oceanography, North Atlantic Deep Water, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Conveyor belt, 01 natural sciences, Ocean dynamics, Current (stream), Geophysics, Oceanography, 13. Climate action, General Circulation Model, General Earth and Planetary Sciences, Thermohaline circulation, 14. Life underwater, Geology, 0105 earth and related environmental sciences
Abstract: A global general circulation model analyzed with a Lagrangian methodology is used to describe and quantify the paths, transports, and characteristics of the “warm” waters forming the upper branch of the conveyor belt in the North Atlantic Ocean. The total transport for this branch turns out to be 17.8 Sv in the North Atlantic at 20°N: 11.8 Sv are composed of waters coming from the two classical origins, the Drake Passage and the Indonesian Throughflow, which contribute with 6.5 and 5.3 Sv respectively. The remaining 6 Sv find their origins partly in the passage between Antarctica and the Australian Continent (with 3.1 Sv) and partly in the Indo-Atlantic sector itself (i.e., with 2.9 Sv). The geographical structure of the different routes emphasizes the role of the Southern Ocean and large-scale current systems in water mass transformation and distribution.
Published: 2001

27. Salt conservation, free surface, and varying levels: A new formulation for ocean general circulation models

Author: Gurvan Madec, Guillaume Roullet, Laboratoire d'océanographie dynamique et de climatologie (LODYC), and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Surface (mathematics), Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, Discretization, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Soil Science, Flux, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Aquatic Science, Oceanography, 01 natural sciences, Geochemistry and Petrology, Potential vorticity, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, Gravity wave, Physics::Atmospheric and Oceanic Physics, Oceanography: General: Numerical modeling, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Mathematics, Ecology, 010505 oceanography, Paleontology, Forestry, Mechanics, Nonlinear system, Geophysics, Volume (thermodynamics), 13. Climate action, Space and Planetary Science, Free surface, Oceanography: Physical: Surface waves and tides
Abstract: International audience; In order to clarify the link between ocean salt content (OSC) conservation and the freshwater flux formulation in ocean general circulation models (OGCMs), a varying level thickness, nonlinear free surface version of the OPA is presented. Linear/nonlinear free surface equations are solved using an original approach based on an explicit damping of fast external gravity waves. The method leaves both the potential vorticity equation and the equilibrium state unchanged. Its numerics and cost are quite similar to those of implicit schemes. When nonlinearities are kept, a variable first level thickness is required. Its discretization is determined by volume and energy constraints. The OSC conservation depends on the surface kinematic equation used. Four formulations are presented: (1) virtual salt flux (fixed ocean volume and no volume flux), (2) natural (fixed ocean volume and volume flux), (3) linear free surface (fixed volume and volume flux computed from a linear free surface equation), and (4) assumption free (variable volume computed from a nonlinear free surface equation). Their impact is illustrated in 25 year low-resolution global OGCM simulations. In all cases the first-order ocean response is quite similar, as the concentration-dilution effect always exists. Formulations 4 and 2 ensure a strict conservation of the OSC. Nevertheless, the difference in formulation 3 is not strong enough to play a significant role: the conservation is almost perfect. Only formulation 1 neglects fresh water-driven surface pumping. This mainly modifies the sea surface salinity of the ocean basin where river runoffs are strong. No significant difference is found between the other formulations as a large time step dampens high-frequency free surface motion. The best compromise for climate is the linear free surface formulation. It allows a nearly exact OSC conservation, introduces the fresh water-driven pumping, and runs faster than all the other formulations.
Published: 2000

28. The seasonal cycle in coupled ocean-atmosphere general circulation models

Author: Gerald A. Meehl, Akira Noda, Ayako Abe-Ouchi, Gurvan Madec, Byron A. Boville, Eric Guilyardi, Ronald J. Stouffer, Curt Covey, Gary L. Russell, Ulrich Cubasch, J.-S. von Storch, T. C. Johns, George J. Boer, Scott B. Power, Erich Roeckner, Xing-Jian Jiang, Laurent Fairhead, Gregory M. Flato, Edwin K. Schneider, Ron L. Miller, H. Le Treut, Laurent Terray, H. B. Gordon, Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS), CERFACS, Laboratoire d'océanographie dynamique et de climatologie (LODYC), and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheric Science, Coupled model intercomparison project, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Global warming, Northern Hemisphere, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Seasonality, 010502 geochemistry & geophysics, medicine.disease, Atmospheric sciences, Atmospheric temperature, 01 natural sciences, Standard deviation, Physics::Geophysics, Latitude, 13. Climate action, Climatology, medicine, Climate sensitivity, Environmental science, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences
Abstract: We examine the seasonal cycle of near-surface air temperature simulated by 17 coupled ocean-atmosphere general circulation models participating in the Coupled Model Intercomparison Project (CMIP). Nine of the models use ad hoc “flux adjustment” at the ocean surface to bring model simulations close to observations of the present-day climate. We group flux-adjusted and non-flux-adjusted models separately and examine the behavior of each class. When averaged over all of the flux-adjusted model simulations, near-surface air temperature falls within 2 K of observed values over the oceans. The corresponding average over non-flux-adjusted models shows errors up to ∼6 K in extensive ocean areas. Flux adjustments are not directly applied over land, and near-surface land temperature errors are substantial in the average over flux-adjusted models, which systematically underestimates (by ∼5 K) temperature in areas of elevated terrain. The corresponding average over non-flux-adjusted models forms a similar error pattern (with somewhat increased amplitude) over land. We use the temperature difference between July and January to measure seasonal cycle amplitude. Zonal means of this quantity from the individual flux-adjusted models form a fairly tight cluster (all within ∼30% of the mean) centered on the observed values. The non-flux-adjusted models perform nearly as well at most latitudes. In Southern Ocean mid-latitudes, however, the non-flux-adjusted models overestimate the magnitude of January-minus-July temperature differences by ∼5 K due to an overestimate of summer (January) near-surface temperature. This error is common to five of the eight non-flux-adjusted models. Also, over Northern Hemisphere mid-latitude land areas, zonal mean differences between July and January temperatures simulated by the non-flux-adjusted models show a greater spread (positive and negative) about observed values than results from the flux-adjusted models. Elsewhere, differences between the two classes of models are less obvious. At no latitude is the zonal mean difference between averages over the two classes of models greater than the standard deviation over models. The ability of coupled GCMs to simulate a reasonable seasonal cycle is a necessary condition for confidence in their prediction of long-term climatic changes (such as global warming), but it is not a sufficient condition unless the seasonal cycle and long-term changes involve similar climatic processes. To test this possible connection, we compare seasonal cycle amplitude with equilibrium warming under doubled atmospheric carbon dioxide for the models in our data base. A small but positive correlation exists between these two quantities. This result is predicted by a simple conceptual model of the climate system, and it is consistent with other modeling experience, which indicates that the seasonal cycle depends only weakly on climate sensitivity.
Published: 2000

29. The water masses along the western boundary of the south and equatorial Atlantic

Author: Aida F. Ríos, Herlé Mercier, Marie-José Messias, Michel Arhan, Laurent Mémery, Carmen G. Castro, Xosé Antón Álvarez-Salgado, Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique des océans (LPO), 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), Instituto de Investigaciones Marinas, and Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)
Subjects: Water mass, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, 010505 oceanography, North Atlantic Deep Water, Geology, Aquatic Science, 01 natural sciences, Gulf Stream, Oceanography, Ocean gyre, Circumpolar deep water, Mode water, Thermohaline circulation, 14. Life underwater, Subtropical front, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences
Abstract: 30 pages, 1 table, 20 figures, A quasi-meridional hydrographic section located offshore from South America from 50°S to 10°N, and three shorter transverse lines to the continental slope, are used for a descriptive study of the water masses along the western boundary of the South and Equatorial Atlantic. At the upper and intermediate levels, the tracer analysis provides geographical limits of the wind-driven circulation regimes, and a comparison of the tracer values at the continental slope and along the meridional section shows where the boundary currents originate. At depths shallower than about 200 m, the subdivision of the subtropical gyre into two cells separated by the Subtropical Countercurrent near 28°S, that was pointed out in a previous study, is corroborated. South of this front, a warm variety (∼18°C) of Subtropical Mode Water in the inner recirculation of the Brazil Current appears, despite its limited extent, as a southern counterpart of the North Atlantic 18°C water. At the deep levels, the Upper Circumpolar Water and Upper North Atlantic Deep Water enter the South Atlantic in a significantly overlapping density range. The ensuing lateral encounter of both water masses occurs at 26°S near the western boundary, where most of the boundary flow of the latter water is stopped and deflected seaward by the base of the subtropical gyre. Other tracer anomalies signal significant eastward escapes of North Atlantic Deep Water: within two jets at about two degrees of latitude on either side of the equator, in another narrow current at 10°S, and at 34°S. The latter latitude marks the confluence, and eastward deflection, of the opposite boundary currents of Lower North Atlantic Deep Water and Lower Circumpolar Water. Near the bottom of the Argentine Basin, the Weddell Sea Deep Water that flows westward north of the Zapiola Ridge is more recently ventilated than the water carried by the boundary current near the Falkland Escarpment. While a part of it flows anticyclonically around the ridge, another part turns equatorward and enhances the southern property signatures of the water farther north, This investigation was supported by IFREMER (Grant 210161), INSU (Institut National des Sciences de l'Univers) and the CNRS (Centre de la Recherche Scientifique), in the framework of the Programme National d'Etude de la Dynamique du Climat (PNEDC) and its WOCE/France subprogramme. X.A. Alvarez-Salgado, C.G. Castro, and A.F. Rios acknowledge financial support from the Spanish CICYT (Contract No ANT93-1156-E)
Published: 2000

30. Upper ocean variability between Iceland and Newfoundland, 1993-1998

Author: Hedinn Valdimarsson, Gilles Reverdin, Nathalie Verbrugge, Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), 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 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), 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)-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)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Effects of global warming on oceans, Soil Science, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Aquatic Science, Oceanography, 01 natural sciences, Oceanography: Physical: Sea level variations, Oceanography: Physical: Hydrography, Geochemistry and Petrology, Ocean gyre, Oceanography: General: Climate and interannual variability, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, World Ocean Circulation Experiment, Sea level, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, geography, geography.geographical_feature_category, Ecology, 010505 oceanography, Meteorology and Atmospheric Dynamics: Ocean/atmosphere interactions, Paleontology, Forestry, Westerlies, Sea surface temperature, Geophysics, 13. Climate action, Space and Planetary Science, Climatology, Thermohaline circulation, Ocean heat content, Geology
Abstract: International audience; We investigate the variability of upper ocean temperature and surface salinity between Iceland and Newfoundland along World Ocean Circulation Experiment line AX2 in 1993-1998. North of 54°N, as well as close to Newfoundland, deviations from the seasonal cycle indicate upper ocean warming from 1994 to 1998, with largest anomalous warming during late 1995/early 1996 and during the winter 1997/1998. North of 54°N, surface salinity increases after mid-1996. The winter of 1995/1996 is the first winter of weak westerlies after more than 20 years of strong westerly conditions in the subarctic gyre, and the ocean loses less heat during that winter than during a normal year. The magnitude of upper ocean heat content change is at least twice as large as what results from the change in air-sea fluxes, which indicates a complementary contribution to heat content change by advection. Altimetric sea level data indicate also an increase of sea level of the order of 6.5 cm during that year, out of which more than 4 cm is contributed by the steric change associated with the temperature increase. A principal component analysis of the sea level data suggests that the increase sensed along line AX2 west of the Reykjanes ridge is found in most of the subpolar gyre, although to a lesser extent in most other areas.
Published: 1999

31. Variations of ƒCO2and air-sea flux of CO2in the Greenland Sea gyre using high-frequency time series data from CARIOCA drift buoys

Author: E. M. Hood, L. Merlivat, T. Johannessen, Laboratoire d'océanographie dynamique et de climatologie (LODYC), and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, Weather forecasting, Soil Science, Flux, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Aquatic Science, Oceanography, computer.software_genre, 01 natural sciences, Wind speed, Atmosphere, Geochemistry and Petrology, Ocean gyre, Earth and Planetary Sciences (miscellaneous), Sea ice, Time series, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, geography, geography.geographical_feature_category, Ecology, 010505 oceanography, Paleontology, Forestry, Sea surface temperature, Geophysics, 13. Climate action, Space and Planetary Science, Climatology, Environmental science, computer
Abstract: International audience; A 6 month, high-frequency (hourly) time series of fCO2 and sea surface temperature measured by CARIOCA drift buoys in the Greenland Sea gyre is presented. The fCO2 shows the effects of photosynthetic activity in the summer, with fCO2 values as low as 260 μatm, followed by an increase to approximately 310 μatm in the late fall and winter due to mixing with CO2-rich deep water from below, remineralization, and gas exchange. The time series shows that fCO2 in the Greenland Sea gyre is undersaturated with respect to the atmosphere year-round, having an average ΔfCO2 of -71 μatm. Linear correlations between the measured fCO2 normalized to a constant temperature of -1°C and sea surface temperature (SST) are used to construct high-resolution fCO2 and air-sea CO2 flux maps for the Greenland Sea gyre area using SST and wind speed data from the European Center for Medium-Range Weather Forecasting and ice information from the Special Sensor Microwave/Imager on a 0.5°×0.5° grid. The CO2 flux for the Greenland Sea gyre calculated for 1996-1997 considering the effects of blockage of gas exchange by sea ice is estimated to be -2.4 to -4.2 × 1012 g C yr-1 depending on the gas exchange parameterization used.
Published: 1999

32. Performance of the OPA/ARPEGE-T21 global ocean-atmosphere coupled model

Author: Gurvan Madec, Eric Guilyardi, Laboratoire d'océanographie dynamique et de climatologie (LODYC), and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, Computer simulation, Atmospheric circulation, Ocean current, Equator, 0207 environmental engineering, Energy balance, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 02 engineering and technology, 01 natural sciences, Atmosphere, 13. Climate action, Climatology, 14. Life underwater, 020701 environmental engineering, Thermocline, Southern Hemisphere, 0105 earth and related environmental sciences
Abstract: The climatology of the OPA/ARPEGE-T21 coupled general circulation model (GCM) is presented. The atmosphere GCM has a T21 spectral truncation and the ocean GCM has a 2°×1.5° average resolution. A 50-year climatic simulation is performed using the OASIS coupler, without flux correction techniques. The mean state and seasonal cycle for the last 10 years of the experiment are described and compared to the corresponding uncoupled experiments and to climatology when available. The model reasonably simulates most of the basic features of the observed climate. Energy budgets and transports in the coupled system, of importance for climate studies, are assessed and prove to be within available estimates. After an adjustment phase of a few years, the model stabilizes around a mean state where the tropics are warm and resemble a permanent ENSO, the Southern Ocean warms and almost no sea-ice is left in the Southern Hemisphere. The atmospheric circulation becomes more zonal and symmetric with respect to the equator. Once those systematic errors are established, the model shows little secular drift, the small remaining trends being mainly associated to horizontal physics in the ocean GCM. The stability of the model is shown to be related to qualities already present in the uncoupled GCMs used, namely a balanced radiation budget at the top-of-the-atmosphere and a tight ocean thermocline.
Published: 1997

33. The macro- and megabenthic fauna on the continental shelf of the eastern Amundsen Sea, Antarctica

Author: Peter Enderlein, Chester J. Sands, Lenaïg G. Hemery, Mark O′Loughlin, Adrian G. Glover, Christopher L. Mah, Thomas Saucède, Tomás Munilla, Bruno David, Sammy De Grave, Katrin Linse, D. K.A. Barnes, Marc Eléaume, Huw J. Griffiths, Niki Davey, Benjamin Pierrat, Rafael Martín-Ledo, Angelika Brandt, Cédric d′Udekem d′Acoz, Jan M. Strugnell, British Antarctic Survey ( BAS ), Natural Environment Research Council ( NERC ), Biocenter Grindel and Zoological Museum, University of Hamburg, National Institute of Water and Atmosphere Research [Nelson] ( NIWA ), Biogéosciences [Dijon] ( BGS ), Université de Bourgogne ( UB ) -AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique ( CNRS ), Museum of Natural History, Oxford University, Integrated Marine Information System ( IMIS ), Royal Belgian Institute of Natural Sciences ( RBINS ), Biologie des Organismes et Ecosystèmes Aquatiques ( BOREA ), Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Muséum National d'Histoire Naturelle ( MNHN ) -Institut de Recherche pour le Développement ( IRD ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université des Antilles ( UA ), Department of Zoology, The Natural History Museum, Department of Invertebrate Zoology, Smithsonian Institution-National Museum of Natural History, Area de Zoología, Universidad de Extremadura, Laboratorio de Zoologia, Universitat Autònoma de Barcelona [Barcelona] ( UAB ), Marine Biology Section, Museum Victoria [Melbourne], Department of Genetics, La Trobe University [Melbourne]-La Trobe Institute for Molecular Science, Study funded by The Natural Environment Research Council., British Antarctic Survey (BAS), Natural Environment Research Council (NERC), National Institute of Water and Atmosphere Research [Nelson] (NIWA), Biogéosciences [UMR 6282] (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), University of Oxford, Integrated Marine Information System (IMIS), Royal Belgian Institute of Natural Sciences (RBINS), Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Universidad de Extremadura - University of Extremadura (UEX), Universitat Autònoma de Barcelona (UAB), Biogéosciences [UMR 6282] [Dijon] (BGS), Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique (CNRS), University of Oxford [Oxford], and Universidad de Extremadura (UEX)
Subjects: 0106 biological sciences, 010504 meteorology & atmospheric sciences, Fauna, [SDV.BID]Life Sciences [q-bio]/Biodiversity, Aquatic Science, Oceanography, 01 natural sciences, Abundance, Abundance (ecology), Megafauna, 14. Life underwater, Transect, Southern Ocean, 0105 earth and related environmental sciences, [ SDV.BID ] Life Sciences [q-bio]/Biodiversity, geography, [ SDE.BE ] Environmental Sciences/Biodiversity and Ecology, geography.geographical_feature_category, Continental shelf, 010604 marine biology & hydrobiology, Geology, Biodiversity, 15. Life on land, Pine Island, Benthic zone, Species richness, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Megabenthos, Bay
Abstract: 11 pages; International audience; In 2008 the BIOPEARL II expedition on board of RRS James Clark Ross sailed to the eastern Amundsen Sea Embayment and Pine Island Bay, one of the least studied Antarctic continental shelf regions due to its remoteness and ice cover. A total of 37 Agassiz trawls were deployed at depth transects along the continental and trough slopes. A total of 5469 specimens, belonging to 32 higher taxonomic groups and more than 270 species, were collected. Species richness per station varied from 1 to 55. The benthic assemblages were dominated by echinoderms and clearly different to those in the Ross, Scotia and Weddell seas. Here we present the macro- and megafaunal assemblage structure, its species richness and the presence of several undescribed species.
Published: 2013

34. Southern Ocean transformation in a coupled model with and without eddy mass fluxes

Author: Gurvan Madec, Eric Guilyardi, Kevin Speer, Laboratoire d'océanographie dynamique et de climatologie (LODYC), and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheric Science, Water mass, Isopycnal, Buoyancy, 010504 meteorology & atmospheric sciences, Atmospheric circulation, Mixed layer, 020206 networking & telecommunications, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 02 engineering and technology, engineering.material, Oceanography, Atmospheric sciences, 01 natural sciences, Circulation (fluid dynamics), Eddy, 13. Climate action, Climatology, 0202 electrical engineering, electronic engineering, information engineering, engineering, Upwelling, 14. Life underwater, Geology, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences
Abstract: A coupled air–sea general circulation model is used to simulate the global circulation. Differentparameterizations of lateral mixing in the ocean by eddies, horizontal, isopycnal, and isopycnalplus eddy advective flux, are compared from the perspective of water mass transformation inthe Southern Ocean. The different mixing physics imply different buoyancy equilibria in thesurface mixed layer, different transformations, and therefore a variety of meridional overturningstreamfunctions. The coupled-model approach avoids strong artificial water mass transformationassociated with relaxation to prescribed mixed layer conditions. Instead, transformationresults from the more physical non-local, nonlinear interdependence of sea-surface temperature,air–sea fluxes, and circulation in the model’s atmosphere and ocean. The developmentof a stronger mid-depth circulation cell and associated upwelling when eddy fluxes arepresent, is examined. The strength of overturning is diagnosed in density coordinates using thetransformation framework. DOI: 10.1034/j.1600-0870.2000.01060.x
Published: 2011

35. 4th CO2 International Conference held in Carqueiranne, France, 13-17 September 1993

Author: Fung, I., Lambert, G., Merlivat, L., Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Centre des Faibles Radioactivités, and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, 010504 meteorology & atmospheric sciences, 13. Climate action, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 01 natural sciences, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: Atmospheric CO2 has been studied since the beginning of the 19th century. After rough evaluations by Dalton (680 ppmv) and Thenard (391 ppmv), an early systematic series of measurements was carried out by the Swiss chemist Nicolas Théodore de Saussure (1830, working in the vicinity of Geneva. He discovered the daily CO2 cycle, with concentrations between 315 and 540 ppmv at noon, and between 321 and 574 ppmv at night.DOI: 10.1034/j.1600-0889.47.issue1.1.x
Published: 2011

36. Seasonal variation of the CO2 exchange coefficient over the global ocean using satellite wind speed measurements

Author: J. ETCHETO, J. BOUTIN, L. MERLIVAT, Laboratoire d'océanographie dynamique et de climatologie (LODYC), and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, 13. Climate action, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 14. Life underwater, 010501 environmental sciences, 01 natural sciences, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: We used one year (July 1987 to June 1988) of wind speed measurements made by the microwave radiometer SSM/I to determine the CO2 exchange coefficient between air and sea on a global scale through the Liss and Merlivat relationship. We determined the seasonal variation in every region of the world ocean. It can be as high as a factor of 4 in some areas. An estimate of the accuracy of the retrieved wind speeds showed that this variation is likely to be underestimated. The global averaged CO2 exchange coefficient obtained is 3.34. 10-2 mol m-2 yr-1µatm-1, close to previous estimates. A study of the errors on the retrieved wind speed showed that the exchange coefficient is likely to be underestimated and could be as high as 4 10-2 mol m-2 yr-1µatm-1. We combined these results with various estimates of the annual CO2 partial pressure gradient at the air sea surface and get a net flux absorbed by the ocean. The flux so determined is not meaningful, however, since the covariant variability of the exchange coefficient and of the CO2 partial pressure gradient is not taken into account.DOI: 10.1034/j.1600-0889.1991.00017.x
Published: 2011

37. Modelling of gas flux through bubbles at the air-water interface

Author: Liliane Merlivat, Laurent Mémery, Laboratoire d'océanographie dynamique et de climatologie (LODYC), and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, Atmospheric Science, Supersaturation, SIMPLE (dark matter experiment), 010504 meteorology & atmospheric sciences, Chemistry, 010604 marine biology & hydrobiology, Bubble, Thermodynamics, Breaking wave, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 01 natural sciences, Overpressure, 13. Climate action, Mass transfer, Solubility, Dissolution, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: A theoretical approach to gas transfer by bubbles created by breaking waves at the air-waterinterface is undertaken. Based on a simple model, this study affords a basic understanding of thephysical mechanisms. The behaviour of a single bubble is examined. Similarities and differencesbetween the formulation of gas fluxes across a “flat” air-water interface and through bubbles areshown. The gas flux through bubbles is not strictly proportional to the solubility and to thedifference of concentrations between the bulk of the water and the surface. Nevertheless, fortrace gases, a linear relationship with this difference of concentrations, increasing with solubilityis predicted. Overpressure in the bubbles and dissolution favour invasion into the water andimply a water supersaturation at equilibrium. This supersaturation is more important when thegas solubility is low. The r61e of surfactants is studied and it is found that they can reduce the gasexchange by a factor of 5. The consequences of the model for the transfer velocity are brieflypresented. A better definition of the bubble lifetime, i t . , a better representation of waterdynamics under a breaking wave, is necessary to make more reliable model predictions, mostimportantly for gases with low solubility. Theoretical studies on the bubble source are necessaryin order to avoid, as far as possible, the use of the bubble distribution. DOI: 10.1111/j.1600-0889.1985.tb00075.x
Published: 2011

38. Skeletal growth, ultrastructure and composition of the azooxanthellate scleractinian coral Balanophyllia regia

Author: Julius Nouet, C. Djediat, Isabelle Domart-Coulon, C. Brahmi, Anders Meibom, Dominique Doumenc, Jarosław Stolarski, Stéphanie Auzoux-Bordenave, David Smith, Laboratoire de Minéralogie et Cosmochimie du Muséum (LMCM), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Institut Paleobiol (PAN), Institut Paleobiol, Station de Biologie Marine de Concarneau, Direction générale déléguée à la Recherche, à l’Expertise, à la Valorisation et à l’Enseignement-Formation (DGD.REVE), Muséum national d'Histoire naturelle (MNHN)-Muséum national d'Histoire naturelle (MNHN), Interactions et dynamique des environnements de surface (IDES), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Molécules de Communication et Adaptation des Micro-Organismes (MCAM), Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut National de la Santé et de la Recherche Médicale (INSERM), and Muséum national d'Histoire naturelle (MNHN)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, Cnidaria, Biomineralization, Phases, 010504 meteorology & atmospheric sciences, Porites, Cells, Coral, Transport, Scleractinia, Azooxanthellate, [SDV.BC]Life Sciences [q-bio]/Cellular Biology, Aquatic Science, 010603 evolutionary biology, 01 natural sciences, Mineralization (biology), Calcification, Chromophile cells, 14. Life underwater, [SDV.BDD]Life Sciences [q-bio]/Development Biology, 0105 earth and related environmental sciences, Calicoblastic epithelium, Matrix, biology, Growth rate, Anatomy, biology.organism_classification, Calcein, Ultrastructure, Biophysics, Mechanism, Coelenterata
Abstract: International audience; The biomineralization process and skeletal growth dynamics of azooxanthellate corals are poorly known. Here, the growth rate of the shallow-water dendrophyllid scleractinian coral Balanophyllia regia was evaluated with calcein-labeling experiments that showed higher lateral than vertical extension. The structure, mineralogy and trace element composition of the skeleton were characterized at high spatial resolution. The epitheca and basal floor had the same ultrastructural organization as septa, indicating a common biological control over their formation. In all of these aragonitic skeletal structures, two main ultrastructural components were present: “centers of calcification” (COC) also called rapid accretion deposits (RAD) and “fibers” (thickening deposits, TD). Heterogeneity in the trace element composition, i.e., the Sr/Ca and Mg/Ca ratios, was correlated with the ultrastructural organization: magnesium was enriched by a factor three in the rapid accretion deposits compared with the thickening deposits. At the interface with the skeleton, the skeletogenic tissue (calicoblastic epithelium) was characterized by heterogeneity of cell types, with chromophile cells distributed in clusters regularly spaced between calicoblasts. Cytoplasmic extensions at the apical surface of the calicoblastic epithelium created a three-dimensional organization that could be related to the skeletal surface microarchitecture. Combined measurements of growth rate and skeletal ultrastructural increments suggest that azooxanthellate shallow-water corals produce well-defined daily growth steps
Published: 2010

39. First observations of deep-sea coral reefs along the Angola margin

Author: Jean-François Bourillet, Samuel P. Iglésias, Myriam Sibuet, Bruno Savoye, Karine Olu, E Le Guilloux, Laboratoire Environnement Profond (LEP), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Unité de recherche Géosciences Marines (Ifremer) (GM), Station de Biologie Marine de Concarneau, Direction générale déléguée à la Recherche, à l’Expertise, à la Valorisation et à l’Enseignement-Formation (DGD.REVE), Muséum national d'Histoire naturelle (MNHN)-Muséum national d'Histoire naturelle (MNHN), Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Etudes des Ecosystèmes Profonds (EEP), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), and Géosciences Marines (GM)
Subjects: 010504 meteorology & atmospheric sciences, Angola margin, Coral, 010502 geochemistry & geophysics, Oceanography, Lucinids, 01 natural sciences, Deep sea, Paleontology, Lophelia, 14. Life underwater, Reef, 0105 earth and related environmental sciences, [SDV.EE]Life Sciences [q-bio]/Ecology, environment, geography, geography.geographical_feature_category, biology, Continental shelf, Lucinidae, Deep-sea corals, Coral reef, biology.organism_classification, Deep sea corals, Lophelia pertusa, Habitat mapping, ROV, Environmental issues with coral reefs, Geology
Abstract: International audience; The West African continental slope is an important theatre for geological survey prospecting and drilling for hydrocarbons but little is known about local deep-sea biological communities at these depths. While shallow-water reefs are common and well-known features in the tropics, only few records of deep-water corals exist at low latitudes, and most of them have been reported by historical oceanographic cruises undertaking circum-navigations of the world. This study, based on a multi-disciplinary approach, presents a description of newly discovered deep-water coral reef communities along the Angola margin. Data from ROV, multibeam bathymetry, side-scan sonar and seismics from a deep-towed acoustic system (SAR) were used to describe the morphology of the coral mounds and their relationship with the local geological setting. The reef-building scleractinian coral Lophelia pertusa has colonised carbonate mounds that reach heights of ca. 30 in and follow an orientation that is correlated with salt tectonic processes. Recent erosion is suggested as a process that influences the shape of the mounds. Sixteen fish taxa were identified during the ROV video surveys, with some of them likely to have a strong affinity with dense-living corals. The species observed belong to families commonly associated with deep-water corals (i.e. Sebastidae, Berycidae, Lophiidae and Chaunacidae), except an abundant species belonging to the family Zoarcidae, rarely observed in this type of environment. Lucinidae shells were found around mounds. As this bivalve family is indicative of reduced sediment and generally associated with cold-seep environments, this finding could revive the debate over the relationship between the distribution of cold-water coral habitat and gas seeps. However, there is no present-day nutritional relationship between living coral and chemosynthetic-derived biomass. The possible role of fluid expulsion in carbonate precipitation acting as the first step for coral colonisation is nevertheless discussed
Published: 2009

40. The near surface tropical Atlantic in 1982–1984: Results from a numerical simulation and a data analysis

Author: Alain Morlière, Jean-Marc Verstraete, Gilles Reverdin, P. Delécluse, P. Andrich, C. Lévy, Laboratoire d'océanographie dynamique et de climatologie (LODYC), and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: VARIATION SAISONNIERE, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, Equator, Wind stress, UPWELLING, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], COURANT EQUATORIAL, Forcing (mathematics), Aquatic Science, 01 natural sciences, COURANT SUBSUPERFICIEL, 010305 fluids & plasmas, 0103 physical sciences, 0105 earth and related environmental sciences, Ocean current, Geology, MODELISATION, VARIATION INTERANNUELLE, CIRCULATION OCEANIQUE, Ocean surface topography, Oceanography, PROFIL VERTICAL, 13. Climate action, Climatology, THERMOCLINE, SIMULATION, Upwelling, Tide gauge, Thermocline
Abstract: Isotherm vertical displacements within the thermocline and surface currents were investigated in the tropical Atlantic Ocean from 12°N to 12°S in 1982–1984, the period of the FOCAL-SEQUAL experiment. The study is based on a numerical simulation of an oceanic general circulation model tuned for the study of the equatorial regions, and on the analysis of the large scale thermocline displacements and currents using observed temperature profiles. Ground truth is provided by temperature and currents from moorings, records from inverted echo sounders and tide gauges as well as from drifting buoys. Comparison of the analysis with the ground truth shows that some important aspects of the low frequency variability are “captured” by the analysis when the data base is large enough. On large scales, the simulation generally resembles the analysis. Along the equator, the upwelling signal propagates eastward. The seasonal set-up of the westerly winds is associated with large westward currents, and a following overshoot of the zonal dynamic topography. Otherwise, the zonal dynamic topography is in near-equilibrium with the winds. The North Equatorial Countercurrent is portrayed comparably in the analysis and the simulation, where, after starting as a narrow eastward flow near 5°N, it extends northward through the northern summer. Interannual variations are found both in the analysis and the simulation. In particular, the thermocline flattened early in 1984. However, the simulation differs in significant respects from the real world: the equatorial undercurrent is too weak in the east and the model produces too much variability south of the equator. The 20°C isotherm is too shallow above the core of the thermocline, and the surface layer is too stratified. Because the surface layer is where the wind stress, main forcing of the model is applied, major effort will have to be devoted to parameterizing the near-surface downward mixing of momentum, heat and fresh water.
Published: 1991

41. Impact of partial steps and momentum advection schemes in a global ocean circulation model at eddy-permitting resolution

Author: Julien Le Sommer, Aike Beckmann, Elisabeth Rémy, Corine Derval, Anne-Marie Tréguier, Mathew Maltrud, Julie L. McClean, Claus W. Böning, Arne Biastoch, Bernard Barnier, Sébastien Theetten, Gurvan Madec, Thierry Penduff, Sergei K. Gulev, Jean-Marc Molines, Beverly A. de Cuevas, Edmée Durand, Claude Talandier, Joachim Dengg, Laboratoire des Écoulements Géophysiques et Industriels [Grenoble] (LEGI), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique des océans (LPO), 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), Division of Geophysics [Helsinki], Department of Physical Sciences [Helsinki], Helsingin yliopisto = Helsingfors universitet = University of Helsinki-Helsingin yliopisto = Helsingfors universitet = University of Helsinki, Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR), Mercator Océan, Société Civile CNRS Ifremer IRD Météo-France SHOM, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Shirshov Institut of Oceanography, Russian Academy of Sciences [Moscow] (RAS), Fluid Dynamics Group, Los Alamos National Laboratory (LANL), Scripps Institution of Oceanography (SIO - UC San Diego), University of California [San Diego] (UC San Diego), University of California (UC)-University of California (UC), National Oceanography Centre [Southampton] (NOC), University of Southampton, Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), P.P. Shirshov Institute of Oceanology (SIO), Institut des Géosciences de l’Environnement (IGE), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), 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), Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Université Joseph Fourier - Grenoble 1 (UJF), University of Helsinki, Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), University of Helsinki-University of Helsinki, Scripps Institution of Oceanography (SIO), and University of California-University of California
Subjects: 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, Eddy-permitting ocean model, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Oceanography, 01 natural sciences, [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph], Mean flow, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], 14. Life underwater, Global ocean, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Momentum (technical analysis), [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Mechanics of the fluids [physics.class-ph], Advection, 010505 oceanography, Numerical analysis, Boundary current, Gulf Stream, Current (stream), Circulation (fluid dynamics), Eddy/topography interactions, Momentum advection scheme, Eddy permitting ocean model, Climatology, Partial step topography, Geology
Abstract: http://www.springerlink.com/content/w8327463321564n3/fulltext.html; Series of sensitivity tests were performed with a z-coordinate, global eddy-permitting (1/4°) ocean/sea-ice model (the ORCA-R025 model configuration developed for the DRAKKAR project) to carefully evaluate the impact of recent state-of-the-art numerical schemes on model solutions. The combination of an energy–enstrophy conserving (EEN) scheme for momentum advection with a partial step (PS) representation of the bottom topography yields significant improvements in the mean circulation. Well known biases in the representation of western boundary currents, such as in the Atlantic the detachment of the Gulf Stream, the path of the North Atlantic Current, the location of the Confluence, and the strength of the Zapiola Eddy in the south Atlantic, are partly corrected. Similar improvements are found in the Pacific, Indian, and Southern Oceans, and characteristics of the mean flow are generally much closer to observations. Comparisons with other state-of-the-art models show that the ORCA-R025 configuration generally performs better at similar resolution. In addition, the model solution is often comparable to solutions obtained at 1/6 or 1/10° resolution in some aspects concerning mean flow patterns and distribution of eddy kinetic energy. Although the reasons for these improvements are not analyzed in detail in this paper, evidence is shown that the combination of EEN with PS reduces numerical noise near the bottom, which is likely to affect current–topography interactions in a systematic way. We conclude that significant corrections of the mean biases presently seen in general circulation model solutions at eddy-permitting resolution can still be expected from the development of numerical methods, which represent an alternative to increasing resolution.
Published: 2006

42. Gulf stream variability in five oceanic general circulation models

Author: Helmuth Haak, Gaëlle de Coëtlogon, Mats Bentsen, Anne Pardaens, Claude Frankignoul, Claire Delon, Simona Masina, Centre d'étude des environnements terrestre et planétaires (CETP), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Nansen Environmental and Remote Sensing Center [Bergen] (NERSC), 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), Max Planck Institute for Meteorology (MPI-M), Max-Planck-Gesellschaft, Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Catania (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Hadley Centre for Climate Prediction and Research, United Kingdom Met Office [Exeter], Centre d'étude des environnements terrestre et planétaires ( CETP ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire d'océanographie dynamique et de climatologie ( LODYC ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ), Nansen Environmental and Remote Sensing Center - Norway ( NERSC ), Laboratoire d'aérologie - LA ( LA ), Université Paul Sabatier - Toulouse 3 ( UPS ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), Max Planck Institute for Meteorology ( MPI-M ), Istituto Nazionale di Geofisica e Vulcanologia [Catania] ( INGV ), Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Recherche pour le Développement (IRD), 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), and Université Fédérale Toulouse Midi-Pyrénées
Subjects: 010504 meteorology & atmospheric sciences, Atmospheric circulation, Baroclinity, General circulation models, 0207 environmental engineering, 02 engineering and technology, Oceanography, 01 natural sciences, Ocean circulation, Ocean gyre, Currents, 020701 environmental engineering, Atlantic Ocean, 0105 earth and related environmental sciences, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], geography, geography.geographical_feature_category, Ocean models, Ocean current, Rossby wave, Gulf Stream, [ PHYS.PHYS.PHYS-AO-PH ] Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], 13. Climate action, North Atlantic oscillation, Climatology, Thermohaline circulation, Geology
Abstract: Five non-eddy-resolving oceanic general circulation models driven by atmospheric fluxes derived from the NCEP reanalysis are used to investigate the link between the Gulf Stream (GS) variability, the atmospheric circulation, and the Atlantic meridional overturning circulation (AMOC). Despite the limited model resolution, the temperature at the 200-m depth along the mean GS axis behaves similarly in most models to that observed, and it is also well correlated with the North Atlantic Oscillation (NAO), indicating that a northward (southward) GS shift lags a positive (negative) NAO phase by 0–2 yr. The northward shift is accompanied by an increase in the GS transport, and conversely the southward shift with a decrease in the GS transport. Two dominant time scales appear in the response of the GS transport to the NAO forcing: a fast time scale (less than 1 month) for the barotropic component, and a slower one (about 2 yr) for the baroclinic component. In addition, the two components are weakly coupled. The GS response seems broadly consistent with a linear adjustment to the changes in the wind stress curl, and evidence for baroclinic Rossby wave propagation is found in the southern part of the subtropical gyre. However, the GS shifts are also affected by basin-scale changes in the oceanic conditions, and they are well correlated in most models with the changes in the AMOC. A larger AMOC is found when the GS is stronger and displaced northward, and a higher correlation is found when the observed changes of the GS position are used in the comparison. The relation between the GS and the AMOC could be explained by the inherent coupling between the thermohaline and the wind-driven circulation, or by the NAO variability driving them on similar time scales in the models.
Published: 2006

43. Validation of a neuro-variational inversion of ocean colour images

Author: Cédric Jamet, Julien Brajard, Sylvie Thiria, Cyril Moulin, 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 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), Université Pierre et Marie Curie - Paris 6 (UPMC), Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), 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), 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), and 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)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Aerospace Engineering, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Radiation, Atmospheric sciences, 01 natural sciences, 010309 optics, Atmospheric radiative transfer codes, Mediterranean sea, 0103 physical sciences, Phytoplankton, 14. Life underwater, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Remote sensing, Scattering, Atmospheric correction, Astronomy and Astrophysics, Particulates, Geophysics, SeaWiFS, 13. Climate action, Space and Planetary Science, General Earth and Planetary Sciences, Environmental science
Abstract: Ocean colour sensors on board satellite measure the solar radiation reflected by the ocean and the atmosphere. This information, denoted reflectance, is affected for about 90% by air molecules and aerosols in the atmosphere and only for about 10% by water molecules and phytoplankton cells in the ocean. Our method focuses on the chlorophyll- a concentration (chl- a ) retrieval, which is commonly used as a proxy for phytoplankton concentration. Our algorithm, denoted NeuroVaria, computes relevant atmospheric (Angstrom coefficient, optical thickness, single-scattering albedo) and oceanic parameters (chl- a , oceanic particulate scattering) by minimizing the difference over the whole spectrum (visible + near-infrared) between the observed reflectance and the reflectance computed from artificial neural networks that have been trained with a radiative transfer model. This algorithm has been presented in [Jamet, C., Thiria, S., Moulin, C., Crepon, M. Use of a neuro-variational inversion for retrieving oceanic and atmospheric constituents from ocean colour imagery. a feasibility study. J. Atmo. Ocean. Tech. 22 (4), 460–475, doi: 10.1175/JTECH1688.1, 2005]. NeuroVaria has been applied to SeaWiFS imagery in the Mediterranean sea. A comparison in the Mediterranean with in-situ measurements of the water-leaving reflectance, optical thickness and chl- a shows that NeuroVaria is consistent to process accurate atmospheric corrections and chl- a estimation for case-I waters and weakly absorbing aerosols. It validates the first step of this new approach of ocean colour images processing.
Published: 2006

44. A Modeling Study of the Impact of Tropical Instability Waves on the Heat Budget of the Eastern Equatorial Pacific

Author: Gurvan V. Madec, Christophe E. Menkès, Jérôme Vialard, Jean-Philippe Boulanger, Sean C. Kennan, Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Oceanographic Center, and Nova Southeastern University (NSU)
Subjects: 010504 meteorology & atmospheric sciences, 010505 oceanography, Mixed layer, Advection, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, Tropical instability waves, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Forcing (mathematics), Oceanography, 01 natural sciences, Instability, Vortex, 13. Climate action, Downwelling, Climatology, Heat transfer, 14. Life underwater, Physics::Atmospheric and Oceanic Physics, Geology, 0105 earth and related environmental sciences
Abstract: A numerical simulation is used to investigate the mixed layer heat balance of the tropical Pacific Ocean including the equatorial cold tongue and the region of vortices associated with tropical instability waves (TIWs). The study is motivated by a need to quantify the effects that TIWs have on the climatological heat budget of the cold tongue mixed layer; there has been some discrepancy between observations indicating very large equatorward heat transport by TIWs and models that disagree on the full three-dimensional budget. Validation of the model reveals that the TIW-induced circulation patterns are realistic but may have amplitudes about 15% weaker than those in the observations. The SST budget within tropical instabilities is first examined in a frame of reference moving with the associated tropical instability vortices (TIVs). Zonal advection of temperature anomalies and meridional advection of temperature by current anomalies dominate horizontal advection. These effects strongly heat the cold cusps and slightly cool the downwelling areas located at the leading edge of the vortices. Cooling by vertical mixing is structured at the vortex scale and almost compensates for horizontal advective heating in the cold cusps. In contrast to some previous studies, TIW-induced vertical advection is found to be negligible in the SST budget. Cooling by this term is only significant below the mixed layer. The effect of TIWs on the climatological heat budget is then investigated for the region bounded by 2 degrees S - 6 degrees N, 160 degrees - 90 degrees W, where instabilities are most active. TIWinduced horizontal advection leads to a warming of 0.84 degrees C month(-1), which is of the same order as the 0.77 degrees C month(-1) warming effect of atmospheric fluxes, while the mean currents and vertical mixing cool the upper ocean by -0.59 degrees C month(-1) and -1.06 degrees C month(-1), respectively. The cooling effect of TIW-induced vertical advection is also negligible in the long-term surface layer heat budget and only becomes significant below the mixed layer. The results above, and in particular the absence of cancellation between horizontal and vertical TIW-induced eddy advection, are robust in three other sensitivity experiments involving different mixing parameterizations and increased vertical resolution.
Published: 2006

45. Internal and forced variability along a section between Greenland and Portugal in the CLIPPER Atlantic model

Author: Claire Gourcuff, Pascale Lherminier, Claus W. Böning, Gurvan Madec, Anne-Marie Tréguier, Bernard Barnier, Jean-Marc Molines, Thierry Penduff, Herlé Mercier, Lars Czeschel, Laboratoire de physique des océans (LPO), 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 des Écoulements Géophysiques et Industriels [Grenoble] (LEGI), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), 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), Leibniz Institute of Marine Science at the University of Kiel (IFM-GEOMAR), Kiel University, Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), 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: Ocean model, Thermohaline circulation, 010504 meteorology & atmospheric sciences, 010505 oceanography, North Atlantic Deep Water, Meridional overturning, North Atlantic, Oceanography, 01 natural sciences, [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph], Amplitude, Shutdown of thermohaline circulation, Eddy, 13. Climate action, Climatology, 14. Life underwater, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], Hydrography, Climate variability, Clipper (electronics), Geology, 0105 earth and related environmental sciences
Abstract: Numerical models are used to estimate the meridional overturning and transports along the paths of two hydrographic cruises, carried out in 1997 and 2002 from Greenland to Portugal. We have examined the influence of the different paths of the two cruises and found that it could explain 0.4 to 2 Sv of difference in overturning (the precise value is model-dependent). Models show a decrease in the overturning circulation between 1997 and 2002, with different amplitudes. The CLIPPER ATL6 model reproduces well the observed weakening of the overturning in density coordinates between the cruises; in the model, the change is due to the combination of interannual and high-frequency forcing and internal variability associated with eddies and meanders. Examination of the $z$-coordinate overturning reveals model–data discrepancies: the vertical structure in the models does not change as much as the observed one. The East Greenland current variability is mainly wind-forced in the ATL6 model, while fluctuations due to eddies and instabilities explain a large part of the North Atlantic Current variability. The time-residual transport of dense water and heat due to eddy correlations between currents and properties is small across this section, which is normal to the direction of the main current.
Published: 2006

46. Decay of semi-diurnal internal-tide beams due to subharmonic resonance

Author: Chantal Staquet, Theo Gerkema, Pascale Bouruet-Aubertot, Laboratoire des Écoulements Géophysiques et Industriels [Grenoble] (LEGI), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), 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), Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), 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), 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)-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)
Subjects: Physics, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Field (physics), Continental shelf, Internal tide, Equator, Resonance, Geophysics, 01 natural sciences, 010305 fluids & plasmas, Latitude, [SPI.MECA.MEFL]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Fluids mechanics [physics.class-ph], Middle latitudes, 0103 physical sciences, General Earth and Planetary Sciences, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], Beam (structure), 0105 earth and related environmental sciences
Abstract: [1] Results of a numerical study on internal-tide generation are presented, using the nonlinear nonhydrostatic MIT-GCM. In the model runs, a lunar semidiurnal (M2) internal tide beam is generated over the continental shelf break. Its further nonlinear evolution is analysed, in particular the generation of M1 internal tides by Subharmonic Resonance (SR). This is done for three different latitudes: at a mid-latitude, slightly below (i.e., equatorward of) the critical latitude (poleward of which the M1 internal tide cannot propagate as a free wave), and at the equator. In the second case the M2 beam loses much energy to M1 already over the continental slope, yielding a pronounced spectral peak at M1, as well as a distinct M1 signal in the current velocity field. At the equator, the transfer to M1 is less pronounced, but still noticeable. Analysis of the growth rate of M1 yields a timescale of two days.
Published: 2006

47. Biophysical regions identification using an artificial neuronal network: A case study in the South Western Atlantic

Author: Mustapha Lebbah, Martin Saraceno, Christine Provost, Laboratoire d'océanographie dynamique et de climatologie (LODYC), and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, Self-organizing map, Atmospheric Science, 010504 meteorology & atmospheric sciences, Meteorology, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, Aerospace Engineering, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 01 natural sciences, Multiple time dimensions, 14. Life underwater, Cluster analysis, 0105 earth and related environmental sciences, Artificial neural network, 010604 marine biology & hydrobiology, Probabilistic logic, Astronomy and Astrophysics, Identification (information), Sea surface temperature, Geophysics, 13. Climate action, Space and Planetary Science, General Earth and Planetary Sciences, Satellite, Cartography, Geology
Abstract: A classification method based on an artificial neuronal network is used to identify biophysical regions in the South Western Atlantic (SWA). The method comprises a probabilistic version of the Kohonen’s self-organizing map and a Hierarchical Ascending Clustering algorithm. It objectively defines the optimal number of classes and the class boundaries. The method is applied to ocean surface data provided by satellite: chlorophyll-a, sea surface temperature and sea surface temperature gradient, first to means and then, in an attempt to examine seasonal variations, to monthly climatologies. Both results reflect the presence of the major circulation patterns and frontal positions in the SWA. The provinces retrieved using mean fields are compared to previous results and show a more accurate description of the SWA. The classification obtained with monthly climatologies offers the flexibility to include the time dimension; the boundaries of biophysical regions established are not fixed, but vary in time. Perspectives and limitations of the methodology are discussed.
Published: 2006

48. Observations of SST, heat flux and North Atlantic Ocean-atmosphere interaction

Author: Qinyu Liu, Claude Frankignoul, Zhengyu Liu, Na Wen, Physical Oceanography Laboratory, Ocean University of China (OUC), Center for Climatic Research [Madison], Nelson Institute for Environmental Studies, University of Wisconsin-Madison-University of Wisconsin-Madison, Laboratoire d'océanographie dynamique et de climatologie (LODYC), and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Lead (sea ice), [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Forcing (mathematics), 010502 geochemistry & geophysics, 01 natural sciences, Atmosphere, Sea surface temperature, Geophysics, Heat flux, 13. Climate action, North Atlantic oscillation, Climatology, Heat transfer, General Earth and Planetary Sciences, Environmental science, 0105 earth and related environmental sciences, Horseshoe (symbol)
Abstract: [1] The relationship between the observed North Atlantic atmosphere and the forcing of SST and heat flux is investigated using the lagged MCA analysis. The dominant heat flux forcing to the North Atlantic Oscillation is associated with the later summer horseshoe SST forcing. The horseshoe SST is generated largely by the surface heat flux, and then forces the early winter atmosphere through the release of oceanic heat flux into the atmosphere. Independent of the horseshoe SST, there is no significant heat flux forcing on the atmosphere with a lead of longer than 1 month.
Published: 2005

49. Observed mean and mesoscale upper ocean circulation in the midlatitude northeast Atlantic

Author: Gilles Reverdin, Michel Assenbaum, Bernard Le Cann, Jean-Claude Gascard, Laboratoire de physique des océans (LPO), 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'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), Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), 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), 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: Atmospheric Science, 010504 meteorology & atmospheric sciences, Lagrangian circulation, Mesoscale meteorology, Soil Science, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Aquatic Science, Oceanography, 01 natural sciences, Geochemistry and Petrology, Mesoscale eddies, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, Acoustic floats, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, Ecology, Buoy, 010505 oceanography, Ocean current, Rossby wave, Paleontology, Forestry, Geophysics, Eddy, 13. Climate action, Space and Planetary Science, Anticyclone, Climatology, Middle latitudes, Mode water, Northeastern Atlantic, Altimetry, Drifting buoys, Geology
Abstract: Lagrangian instruments and altimetry data are used to investigate the upper ( 0 to similar to 500 m) mean and mesoscale circulations in a region of the midlatitude northeast Atlantic (36 degrees - 47 degrees N, 13 degrees - 23 degrees W), a formation and subduction area of Subpolar Mode Water. Lagrangian data were collected between September 2000 and September 2001 with isobaric subsurface floats, totaling 34.0 float years, and surface drifting buoys, totaling 27.9 buoy years. The near-surface ( 0 - 100 m) mean circulation is dominated by two weak ( similar to 5 cm/s) eastward currents which veer southward in the domain. In the 100- to 500-m-deep layer, these eastward mean currents retroflect westward and form two anticyclonic circulation cells, opened to the west and separated by a cyclonic cell. Eddy kinetic energy is decreasing from the northwest to the southeast of the area, from similar to 100-200 (cm/s)(2) to similar to 20 - 30 (cm/s)(2). Long-lived anticyclones and cyclones display mean coherent displacements, both to the southwest. Westward eddy propagation speeds, close to that of long Rossby waves, increase southward and are consistent with a superposition of beta effect and advection by mean currents. Southward eddy displacements are coherent with the observed mean currents. In the north, anticyclones are seen to consist of Central and Subpolar Mode Water eddies, most of them likely originating from the eastern boundary, whereas in the south, most anticyclonic features result from the influence of "Mediterranean Water Eddies'' (meddies) on the upper layers. Cyclonic activity is concentrated in "cyclonic zones,'' which are seen to exchange floats and water properties.
Published: 2005

50. A fifty-year climatic signal in three Holocene stalagmite records from Mato Grosso, Brazil

Author: Roberto Ventura Santos, Alexandre Seidel, François Soubiès, S. Hirooka, Dominique Genty, Valérie Plagnes, Josyane Ronchail, Alain Mangin, Paléo-environnements tropicaux et variabilité climatique (PALEOTROPIQUE), Instituto de Geociências, Universidade de Brasilia [Brasília] (UnB), Laboratoire d'écologie des hydrosystèmes (LEH), Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), 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), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), 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)-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), Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Université Paris Diderot - Paris 7 (UPD7), ECOSS, Instituto Ecosistemas e Populações Tradicionais, Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), 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), and 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)-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)
Subjects: geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Stalagmite, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 010502 geochemistry & geophysics, Climate history, 01 natural sciences, Proxy (climate), Cave, 13. Climate action, Climatology, Geology, Holocene, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract: Three stalagmites were collected in the “Perolas” cave, 150 km NW of Cuiaba, Mato Grosso, Brazil, in order to reconstruct the climate history of the surrounding region. These stalagmites were similarly formed by stacking of thousands of calcitic pairs of laminae. Microphotographs of polished thin sections were used to count the laminae pairs and measure their width. A reasonable fit was found between the counting results and U/Th and 14C geochronological data, proving that these pairs are annually deposited; and correlations were also found between the annual growth rate of the stalagmites and the annual water excess in the Perolas region, proving that the former parameter could be used as a climatic proxy. Three files of climatic proxy data covering 256 years were thus obtained and statistically treated to restore the historical fluctuations of the climate. Apart from well-documented periodicities, a still poorly known but very strong half-century climatic oscillation appeared in the results.
Published: 2005

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