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1. Halogen chemistry in volcanic plumes: a 1D framework based on MOCAGE 1D (version R1.18.1) preparing 3D global chemistry modelling

Author: Virginie Marécal, Ronan Voisin-Plessis, Tjarda Jane Roberts, Alessandro Aiuppa, Herizo Narivelo, Paul David Hamer, Béatrice Josse, Jonathan Guth, Luke Surl, Lisa Grellier, Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Dipartimento di Scienze della Terra e del Mare [Palermo] (DiSTeM), Università degli studi di Palermo - University of Palermo, Norwegian Institute for Air Research (NILU), Department of Chemistry [Aberdeen], School of Natural and Computing Sciences, University of Aberdeen-University of Aberdeen, STRATO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre Interprofessionnel Technique d'Etude des Pollutions Atmosphériques (CITEPA), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Norsk Institutt for Luftforskning (NILU), VOLC-HAL-CLIM: ANR-18-CE1-0018, and ANR-18-CE01-0018,VOLC-HAL-CLIM,Halogènes volcaniques : de la Terre profonde aux impacts atmosphériques(2018)
Subjects: [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Halogen chemistry, [SDE]Environmental Sciences, Volcanic emissions, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, General Medicine
Abstract: HBr emissions from volcanoes lead rapidly to the formation of BrO within volcanic plumes and have an impact on tropospheric chemistry, at least at the local and regional scales. The motivation of this paper is to prepare a framework for further 3D modelling of volcanic halogen emissions in order to determine their fate within the volcanic plume and then in the atmosphere at the regional and global scales. The main aim is to evaluate the ability of the model to produce a realistic partitioning of bromine species within a grid box size typical of MOCAGE (Model Of atmospheric Chemistry At larGE scale) 3D (0.5∘ × 0.5∘). This work is based on a 1D single-column configuration of the global chemistry-transport model MOCAGE that has low enough computational cost to allow us to perform a large set of sensitivity simulations. This paper uses the emissions from the Mount Etna eruption on 10 May 2008. Several reactions are added to MOCAGE to represent the volcanic plume halogen chemistry. A simple plume parameterisation is also implemented and tested. The use of this parameterisation tends to only slightly limit the efficiency of BrO net production. Both simulations with and without the parameterisation give results for the partitioning of the bromine species, of ozone depletion and of the BrO/SO2 ratio that are consistent with previous studies. A series of test experiments were performed to evaluate the sensitivity of the results to the composition of the emissions (primary sulfate aerosols, Br radical and NO) and to the effective radius assumed for the volcanic sulfate aerosols. Simulations show that the plume chemistry is sensitive to all these parameters. We also find that the maximum altitude of the eruption changes the BrO production, which is linked to the vertical variability of the concentrations of oxidants in the background air. These sensitivity tests display changes in the bromine chemistry cycles that are generally at least as important as the plume parameterisation. Overall, the version of the MOCAGE chemistry developed for this study is suitable to produce the expected halogen chemistry in volcanic plumes during daytime and night-time.
Published: 2023

2. Lunar eclipses illuminate timing and climate impact of medieval volcanism

Author: Guillet, Sébastien, Corona, Christophe, Oppenheimer, Clive, Lavigne, Franck, Khodri, Myriam, Ludlow, Francis, Sigl, Michael, Toohey, Matthew, Atkins, Paul S, Yang, Zhen, Muranaka, Tomoko, Horikawa, Nobuko, Stoffel, Markus, Climate Change Impacts and Risks in the Anthropocene (C-CIA), Institute for Environmental Sciences, University of Geneva, Geneva, Switzerland (University of Geneva), Laboratoire de Géographie Physique et Environnementale (GEOLAB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), University of Cambridge [UK] (CAM), Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-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)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Trinity Centre for Environmental Humanities, Department of History, School of Histories & Humanities, Trinity College Dublin, Dublin, Ireland (Trinity College Dublin), Universität Bern [Bern] (UNIBE), Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan, Canada. (University of Saskatchewan), Department of Asian Languages & Literature, University of Washington, Seattle, WA, USA (University of Washington), Climate Change Impacts and Risks in the Anthropocene (C-CIA), Institute for Environmental Sciences, University of Geneva, Geneva, Switzerland. (University of Geneva), Department of Asian Languages & Literature, University of Washington, Seattle, WA, USA. (University of Washington), ANR-11-IDEX-0004,SUPER,Sorbonne Universités à Paris pour l'Enseignement et la Recherche(2011), European Project: 820047,THERA, European Project: 951649,4-OCEANS, Guillet, Sébastien [0000-0002-0602-0518], Corona, Christophe [0000-0002-7645-6157], Oppenheimer, Clive [0000-0003-4506-7260], Khodri, Myriam [0000-0003-1941-1646], Ludlow, Francis [0000-0003-0008-0314], Toohey, Matthew [0000-0002-7070-405X], Atkins, Paul S. [0000-0002-4048-5036], Stoffel, Markus [0000-0003-0816-1303], Apollo - University of Cambridge Repository, and Atkins, Paul S [0000-0002-4048-5036]
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 13 Climate Action, Multidisciplinary, 530 Physics, 520 Astronomy, article, 704/106/694/1108, 37 Earth Sciences, 3705 Geology, 3709 Physical Geography and Environmental Geoscience, 530 Physik, [SHS.HISPHILSO]Humanities and Social Sciences/History, Philosophy and Sociology of Sciences, 540 Chemistry, 704/106/413, 550 Earth sciences & geology, 900 History
Abstract: Acknowledgements: S.G., C.C., M.K. and M. Stoffel were supported by the Swiss National Science Foundation Sinergia Project CALDERA (CRSII5_183571). S.G. acknowledges A. Harrak (Department of Near and Middle Eastern Civilizations, University of Toronto), F. Espenak (NASA Goddard Space Flight Center), F. Hierink (Institute for Environmental Sciences, University of Geneva) and P. Souyri (Department of East Asian Studies, University of Geneva) for providing advice on the manuscript. F. Lavigne was supported by Institut Universitaire de France (IUF, Academic Institute of France). M.K. received funding from the EUR IPSL – Climate Graduate School project, managed by the ANR within the “Investissements d’avenir” programme under reference ANR-11-IDEX-0004-17-EURE-0006. F. Ludlow received funding from an Irish Research Council Starting Laureate Award (CLICAB project, IRCLA/2017/303). F. Ludlow and Z.Y. also received funding from a European Research Council (ERC) Synergy Grant (4-OCEANS; grant agreement no. 951649) under the European Union’s Horizon 2020 research and innovation programme. M. Sigl received funding from the ERC under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 820047). This paper is a product of the Volcanic Impacts on Climate and Society (VICS) working group., Explosive volcanism is a key contributor to climate variability on interannual to centennial timescales1. Understanding the far-field societal impacts of eruption-forced climatic changes requires firm event chronologies and reliable estimates of both the burden and altitude (that is, tropospheric versus stratospheric) of volcanic sulfate aerosol2, 3. However, despite progress in ice-core dating, uncertainties remain in these key factors4. This particularly hinders investigation of the role of large, temporally clustered eruptions during the High Medieval Period (HMP, 1100–1300 ce), which have been implicated in the transition from the warm Medieval Climate Anomaly to the Little Ice Age5. Here we shed new light on explosive volcanism during the HMP, drawing on analysis of contemporary reports of total lunar eclipses, from which we derive a time series of stratospheric turbidity. By combining this new record with aerosol model simulations and tree-ring-based climate proxies, we refine the estimated dates of five notable eruptions and associate each with stratospheric aerosol veils. Five further eruptions, including one responsible for high sulfur deposition over Greenland circa 1182 ce, affected only the troposphere and had muted climatic consequences. Our findings offer support for further investigation of the decadal-scale to centennial-scale climate response to volcanic eruptions.
Published: 2023

3. Expanded geographic distribution and dietary strategies of the earliest Oldowan hominins and Paranthropus

Author: Plummer, TW, Oliver, JS, Finestone, EM, Ditchfield, PW, Bishop, LC, Blumenthal, SA, Lemorini, C, Caricola, I, Bailey, SE, Herries, AIR, Parkinson, JA, Whitfield, E, Hertel, F, Kinyanjui, RN, Vincent, TH, Li, Y, Louys, J, Frost, SR, Braun, DR, Reeves, JS, Early, EDG, Onyango, B, Lamela-Lopez, R, Forrest, FL, He, H, Lane, TP, Frouin, M, Nomade, S, Wilson, EP, Bartilol, SK, Rotich, NK, Potts, R, 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), Paléocéanographie (PALEOCEAN), 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: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Multidisciplinary
Abstract: The oldest Oldowan tool sites, from around 2.6 million years ago, have previously been confined to Ethiopia’s Afar Triangle. We describe sites at Nyayanga, Kenya, dated to 3.032 to 2.581 million years ago and expand this distribution by over 1300 kilometers. Furthermore, we found two hippopotamid butchery sites associated with mosaic vegetation and a C4 grazer–dominated fauna. Tool flaking proficiency was comparable with that of younger Oldowan assemblages, but pounding activities were more common. Tool use-wear and bone damage indicate plant and animal tissue processing. Paranthropus sp. teeth, the first from southwestern Kenya, possessed carbon isotopic values indicative of a diet rich in C4 foods. We argue that the earliest Oldowan was more widespread than previously known, used to process diverse foods including megafauna, and associated with Paranthropus from its onset. Oldowan tools, consisting of stones with one to a few flakes removed, are the oldest widespread and temporally persistent hominin tools. The oldest of these were previously known from around 2.6 million years ago in Ethiopia, and by 2 million years ago, they were found to be quite widespread. Plummer et al. report on an older fossil site from around 3 to 2.6 million years ago in Kenya, where Oldowan tools were not only present, but were also being used to process a variety of foods, including hippopotamus. Thus, it appears that these tools were widespread much earlier than previous estimates and were widely used for food processing. Which hominins were using these tools remains uncertain, but Paranthropus fossils occur at the site. —SNV Ancient Oldowan sites from Nyayanga show evidence of hippo butchery, plant processing, and the first Paranthropus, a type of extinct hominin, from southwest Kenya.
Published: 2023

4. Temperature Changes Induced by Biogeochemical and Biophysical Effects of Bioenergy Crop Cultivation

Author: Jingmeng Wang, Philippe Ciais, Thomas Gasser, Jinfeng Chang, Hanqin Tian, Zhe Zhao, Lei Zhu, Zhao Li, Wei Li, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), 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: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Environmental Chemistry, General Chemistry
Published: 2023

5. Lead from Notre-Dame Fire Plume Caught 15 km from Paris

Author: Gaël Le Roux, Olivier Masson, Christophe Cloquet, Marie-José Tavella, Magali Beguin-Leprieur, Olivier Saunier, David Baqué, Thierry Camboulive, Julien Berger, Thierry Aigouy, Françoise Maube, Sandrine Baron, Sophie Ayrault, Maxime L’Héritier, Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Pôle Santé Environnement- Direction Environnement (IRSN/PSE-ENV), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Service d'intervention radiologique et de surveillance de l'environnement (IRSN/PSE-ENV/SIRSE), Bureau de Modélisation des transferts dans l'environnement pour l'études des Conséquences des accidents (IRSN/PSE-SANTE/SESUC/BMCA), Service des situations d'urgence et d'organisation de crise (IRSN/PSE-SANTE/SESUC), Institut de Radioprotection et de Sûreté Nucléaire (IRSN)-Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Service d'expertise et d'étude en radioprotection des populations et de la radioactivité dans l'environnement (IRSN/PSE-ENV/SEREN), 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), Géochimie Des Impacts (GEDI), 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: urban fire, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Pb isotopes, Atmospheric Science, Notre-Dame de Paris, Historical monument fire, Space and Planetary Science, Geochemistry and Petrology, lead plume, air monitoring, aerosols
Abstract: International audience; Thanks to the use of filters collected daily in the west of Paris, we confirm the passage of the lead-laden plume following the fire on the roof and spire of Notre-Dame Cathedral in April 2019. The measured concentrations on the filter (Pb = 1.4 μg m–3), scanning electron microscopy and Hysplit simulation, correspond to an estimate of a few hundred kilograms of lead that would have been volatilized and then oxidized in the form of micronic and submicronic aerosols. The concentrations found in the plume are, however, much lower than those found in the environment in the 1980s and 1990s but are 100 times higher than those found in times prior to and after the fire. The isotopic signature of the plume is almost identical to that of the fine Pb dust found inside the Notre-Dame building. It is different from the isotopic signature of the Parisian atmosphere before and after the fire, but it is similar to that of the atmospheric Pb legacy recorded by peat cores over the last 300 years in France. The presence of very fine lead-bearing particles makes them potentially transportable over long distances after large urban fires. Our study shows the value of daily aerosol sampling to retrospectively trace the plumes of air pollutants from industrial accidents but also from historical monument fires such as Notre-Dame in 2019.
Published: 2023

6. Global Observing System Experiments within the Météo-France 4D-Var Data Assimilation System

Author: Chambon, P., Mahfouf, J.-F., Audouin, O., Birman, C., Fourrié, N., Loo, C., Martet, M., Moll, P., Payan, C., Pourret, V., Raspaud, D., Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science
Abstract: Observing system experiments were undertaken within the 4D-Var data assimilation of the Météo-France global numerical weather prediction (NWP) model. A 6-month period was chosen (October 2019–March 2020) where 40 million observations per day were assimilated. The importance of in situ observations provided by aircraft, radiosondes, and surface weather stations, despite their small fractional amount (7%), has been confirmed particularly in the Northern Hemisphere. Moreover, the largest impact over Europe in terms of root-mean-square error (RMSE) scores comes from surface observations. Satellite data play a dominant role over tropical regions and the Southern Hemisphere. Microwave radiances have a more pronounced impact on the long range and on the humidity field than infrared radiances, despite being less numerous (10% versus 80%). Bending angles impact significantly the quality of the upper-troposphere–lower-stratosphere temperature of the tropics and Southern Hemisphere. Atmospheric motion vectors (AMVs) are beneficial in wind forecasts at low and high levels in the tropics and the Southern Hemisphere, but also in the humidity field. Such impacts are only significant during the first 48 h of the forecasts. Scatterometer winds have an impact restricted to low levels that is kept at longer ranges. A comparison with forecast sensitivity–observation impact studies over a 3-month period using the same measure of short-range (24-h) forecast errors reveals that the ranking between the major observing systems is kept between these two ways of measuring observation impact in NWP. From our conclusions, recommendations are provided on possible evolutions of the global observing system for NWP.
Published: 2023

7. Simulations of the Holocene climate in Europe using an interactive downscaling within the iLOVECLIM model (version 1.1)

Author: Frank Arthur, Didier M. Roche, Ralph Fyfe, Aurélien Quiquet, Hans Renssen, Earth Sciences, University of South-Eastern Norway (USN), Vrije Universiteit Amsterdam [Amsterdam] (VU), 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), School of Geography, Earth and Environmental Sciences [Plymouth] (SoGEES), and Plymouth University
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, Stratigraphy, SDG 13 - Climate Action, Paleontology, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment
Abstract: This study presents the application of an interactive downscaling in Europe using iLOVECLIM (a model of intermediate complexity), increasing its atmospheric resolution from 5.56 to 0.25∘ kilometric. A transient simulation using the appropriate climate forcings for the entire Holocene (11.5–0 ka BP) was done for both the standard version of the model and with an interactive downscaling applied. Our results show that simulations from downscaling present spatial variability that agrees better with proxy-based reconstructions and other climate models as compared to the standard model. The downscaling scheme simulates much higher (by at least a factor of 2) precipitation maxima and provides detailed information in mountainous regions. We focus on examples from the Scandes mountains, the Alps, the Scottish Highlands, and the Mediterranean. The higher spatial resolution of the downscaling provides a more realistic overview of the topography and gives local climate information, such as precipitation and temperature gradient, that is important for paleoclimate studies. With downscaling, we simulate similar trends and spatial patterns of the precipitation changes reconstructed by other proxy studies (for example in the Alps) as compared to the standard version. Our downscaling tool is numerically cheap, implying that our model can perform kilometric, multi-millennial simulations and is suitable for future studies.
Published: 2023

8. Siberian carbon sink reduced by forest disturbances

Author: Lei Fan, Jean-Pierre Wigneron, Philippe Ciais, Jérome Chave, Martin Brandt, Stephen Sitch, Chao Yue, Ana Bastos, Xin Li, Yuanwei Qin, Wenping Yuan, Dmitry Schepaschenko, Liudmila Mukhortova, Xiaojun Li, Xiangzhuo Liu, Mengjia Wang, Frédéric Frappart, Xiangming Xiao, Jingming Chen, Mingguo Ma, Jianguang Wen, Xiuzhi Chen, Hui Yang, Dave van Wees, Rasmus Fensholt, Southwest University [Chongqing], Interactions Sol Plante Atmosphère (UMR ISPA), Ecole Nationale Supérieure des Sciences Agronomiques de Bordeaux-Aquitaine (Bordeaux Sciences Agro)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Laboratoire 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), Evolution et Diversité Biologique (EDB), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Department of Geosciences and Natural Resource Management [Copenhagen] (IGN), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH), College of Life and Environmental Sciences [Exeter], University of Exeter, Northwest A and F University, Max Planck Institute for Biogeochemistry (MPI-BGC), Max-Planck-Gesellschaft, Institute of Tibetan Plateau Research, Chinese Academy of Sciences [Beijing] (CAS), Department of Microbiology and Plant Biology, University of Oklahoma (OU), National Sun Yat-Sen University (NSYSU), Sun Yat-Sen University [Guangzhou] (SYSU), V.N. Sukachev Institute of Forest, Siberian Branch of the Russian Academy of Sciences (SB RAS), Siberian Federal University (SibFU), University of Toronto, State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing and Digital Earth (RADI), Chinese Academy of Sciences [Beijing] (CAS)-Chinese Academy of Sciences [Beijing] (CAS), Vrije Universiteit Brussel (VUB), IT University of Copenhagen (ITU), and Earth Sciences
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDE]Environmental Sciences, General Earth and Planetary Sciences, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, SDG 15 - Life on Land
Abstract: International audience; Siberian forests are generally thought to have acted as an important carbon sink over recent decades, but exposure to severe droughts and fire disturbances may have impacted their carbon dynamics. Limited available forest inventories mean the carbon balance remains uncertain. Here we analyse annual live and dead above-ground carbon changes derived from low-frequency passive microwave observations from 2010 to 2019. We find that during this period, the carbon balance of Siberian forests was close to neutral, with the forests acting as a small carbon sink of +0.02+0.03+0.01 PgC yr−1. Carbon storage in dead wood increased, but this was largely offset by a decrease in live biomass. Substantial losses of live above-ground carbon are attributed to fire and drought, such as the widespread fires in northern Siberia in 2012 and extreme drought in eastern Siberia in 2015. These live above-ground carbon losses contrast with ‘greening’ trends seen in leaf area index over the same period, a decoupling explained by faster post-disturbance recovery of leaf area than live above-ground carbon. Our study highlights the vulnerability of large forest carbon stores in Siberia to climate-induced disturbances, challenging the persistence of the carbon sink in this region of the globe.
Published: 2023

9. Primitive Equations Under Location Uncertainty: Analytical Description and Model Development

Author: Tucciarone, Francesco, Mémin, Etienne, Li, Long, Océan Dynamique Observations Analyse (ODYSSEY), Université de Bretagne Occidentale - UFR Sciences et Techniques (UBO UFR ST), Université de Brest (UBO)-Université de Brest (UBO)-Université de Rennes (UR)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-IMT Atlantique (IMT Atlantique), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere
Abstract: Resolving numerically all the scale interactions of ocean dynamics in a high resolution realistic configuration is today far beyond reach, and only large scale representations can be afforded. In this work, we study a stochastic parameterization of the ocean primitive equations derived within the modelling under location uncertainty framework. First numerical assessments built with the NEMO core’s code are provided for a double-gyres configuration.
Published: 2023

10. Modified (Hyper-)Viscosity for Coarse-Resolution Ocean Models

Author: Thiry, Louis, Li, Long, Mémin, Etienne, Océan Dynamique Observations Analyse (ODYSSEY), Université de Bretagne Occidentale - UFR Sciences et Techniques (UBO UFR ST), Université de Brest (UBO)-Université de Brest (UBO)-Université de Rennes (UR)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-IMT Atlantique (IMT Atlantique), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere
Abstract: We present a simple parameterization for coarse-resolution ocean models. To replace computationally expensive high-resolution ocean models, we develop a computationally cheap parameterization for coarse-resolution models based solely on the modification of the viscosity term in advection equations. It is meant to reproduce the mean quantities like pressure, velocity, or vorticity computed from a high-resolution reference solution or using observations. We test this new parameterization on a double-gyre quasi-geostrophic model in the eddy-permitting regime. Our results show that the proposed scheme improves significantly the energy statistics and the intrinsic variability on the coarse mesh. This method shall serve as a deterministic basis model for coarse-resolution stochastic parameterizations in future works.
Published: 2023

11. Challenges in Attributing the 2022 Australian Rain Bomb to Climate Change

Author: Camille Cadiou, Robin Noyelle, Nemo Malhomme, Davide Faranda, 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), Extrèmes : Statistiques, Impacts et Régionalisation (ESTIMR), 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), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), ANR-19-ERC7-0003,BOREAS,Dynamique et thermodynamique des tempêtes de neige en changement climatique(2019), European Project: 101003469,XAIDA, and European Project: 956396,EDIPI
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Attribution, Atmospheric Science, [SDU]Sciences of the Universe [physics], Climate Change, Extreme Precipitation, Australia
Abstract: International audience In February and March 2022, the eastern coast of Australia recorded an unprecedented amount of precipitation with extended floods and damages to properties amounting at least to AUD 2.3 billions. In this paper we use both reanalysis and observations to perform a statistical and dynamical attribution of this precipitation event to climate change. We define 1948-1977 as the counterfactual period and 1990-2019 as the factual one. The statistical attribution is based on fitting the generalized extreme value distribution for 3-days averaged precipitation annual maxima for the two periods, while the dynamical attribution aims at looking at the recurrence properties of sea-level pressure and geopotential height patterns in both periods. We find that the dynamics of the event consists in an unprecedented combination of several factors: a tropical atmospheric river, the presence of the Coral low pressure system and a blocking anticyclone offshore Eastern Australia. Our main finding is that no clear attribution statements can be made, both because of the unprecedented nature of this event, the lack of long high quality available data and the dependence of the results on the La Nina phase of El Nino Southern Oscillation.
Published: 2022

12. Breakdown of Near-Surface Sea Current from High-Frequency Radar Data

Author: Alejandro Cáceres-Euse, Anne Molcard, Natacha Bourg, Dylan Dumas, Charles-Antoine Guérin, Giovanni Besio, Institut méditerranéen d'océanologie (MIO), and 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)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmosphere-ocean interaction, Atmospheric Science, Ocean circulation, Surface observations, Ocean Engineering
Abstract: To assess the contribution of wind drag and Stokes drift on the near-surface circulation, a methodology to isolate the geostrophic surface current from high-frequency radar data is developed. The methodology performs a joint analysis utilizing wind field and in situ surface currents along with an unsupervised neuronal network. The isolation method seems robust in the light of comparisons with satellite altimeter data, presenting a similar time variability and providing more spatial detail of the currents in the coastal region. Results show that the wind-induced current is around 2.1% the wind speed and deflected from the wind direction in the range [18°, 23°], whereas classical literature suggests higher values. The wave-induced currents can represent more than 13% of the ageostrophic current component as function of the wind speed, suggesting that the Stokes drift needs to be analyzed as an independent term when studying surface sea currents in the coastal zones. The methodology and results presented here could be extended worldwide, as complementary information to improve satellite-derived surface currents in the coastal regions by including the local physical processes recorded by high-frequency radar systems. The assessment of the wave and wind-induced currents have important applications on Lagrangian transport studies.
Published: 2022

13. Storm types in Bangladesh: duration, intensity and area of intra‐daily wet events

Author: Moron, Vincent, Acharya, Nachiketa, Hassan, Quamrul Sm, Aix-Marseille Université - Faculté des Arts, Lettres, Langues et Sciences Humaines (AMU ALLSH), Aix Marseille Université (AMU), University of Colorado [Boulder], National Oceanic and Atmospheric Administration (NOAA), and Bangladesh Meteorological Department
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, predictability, [SDE.MCG]Environmental Sciences/Global Changes, 3-hourly rainfall, clustering
Abstract: International audience; We explore the characteristics of 96190 wet events (WE) defined as consecutive 3-hourly rainfall >= 1 mm/3h from a network of 34 stations across Bangladesh. Nearly 60% (5%) of wet events last = 15) hours. The WEs are dynamically clustered into four "canonical" storm types (ST), mostly discretized by their duration, but also their mean and maximal intensity. While durations, total amounts and wet contiguous areas of WEs are positively related, their mean intensity is nearly independent of them. ~ 60% of WEs are associated with ST#1, that is short and small WEs and very low rainfall amounts (usually < 10 mm), ~15% of WEs are associated with either (ST#2) short/small WEs but with intense rainfall, probably mostly related to scattered thunderstorms, or (ST#3) longer/larger WEs but with less intense rainfall. The last ST (ST#4) is rare (~ 6%), related to very long durations and large wet areas, and includes the wettest WEs. It is especially frequent over southeastern Bangladesh. ST#2 to #4 contribute almost equally to the local-scale total amount of rainfall (27-29% each in mean) while ST#1, despite its individual low rainfall amount, still includes ~ 15% of it. ST#2 (ST#4) is related to the highest probability of occurrence of 3-hourly (daily) extremes. ST#4 occurrence is the most impacted by synoptic Indian lows/depressions as well as the main modes of intraseasonal variation, while ST#1 and #2 are also significantly impacted by intraseasonal modes but in reverse manner than ST#4.
Published: 2022

14. Constraining China's land carbon sink from emerging satellite <scp> CO 2 </scp> observations: Progress and challenges

Author: Yilong Wang, Xiangjun Tian, Frédéric Chevallier, Matthew S. Johnson, Sajeev Philip, David F. Baker, Andrew E. Schuh, Feng Deng, Xingying Zhang, Lu Zhang, Dan Zhu, Xuhui Wang, 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 INVerse pour les mesures atmosphériques et SATellitaires (SATINV), 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: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, Ecology, Environmental Chemistry, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, General Environmental Science
Abstract: International audience; Land carbon sink is a vital component for the achievement of China's ambitious carbon neutrality goal, but its magnitude is poorly known. Atmospheric observations and inverse models are valuable tools to constrain the China's land carbon sink. Space-based CO2 measurements from satellites form an emerging data stream for application of such atmospheric inversions. Here, we reviewed the satellite missions that is dedicated to the monitoring of CO2, and the recent progresses on the inversion of China's land carbon sink using satellite CO2 measurements. We summarized the limitations and challenges in current space platforms, retrieval algorithms, and the inverse modeling. It is shown that there are large uncertainties of contemporary satellite-based estimates of China's land carbon sink. We discussed future opportunities of continuous improvements in three aspects to better constrain China's land carbon sink with space-based CO2 measurements.
Published: 2022

15. Quantifying NOx emissions in Egypt using TROPOMI observations

Author: Anthony Rey-Pommier, Frédéric Chevallier, Philippe Ciais, Grégoire Broquet, Theodoros Christoudias, Jonilda Kushta, Didier Hauglustaine, Jean Sciare, 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 INVerse pour les mesures atmosphériques et SATellitaires (SATINV), 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), Cyprus Institute (CyI), and Modelling the Earth Response to Multiple Anthropogenic Interactions and Dynamics (MERMAID)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment
Abstract: Urban areas and industrial facilities, which concentrate the majority of human activity and industrial production, are major sources of air pollutants, with serious implications for human health and global climate. For most of these pollutants, emission inventories are often highly uncertain, especially in developing countries. Spaceborne measurements from the TROPOMI instrument, on board the Sentinel-5 Precursor satellite, are used to retrieve nitrogen dioxide (NO2) column densities at high spatial resolution. Here, we use 2 years of TROPOMI retrievals to map nitrogen oxide (NOx = NO + NO2) emissions in Egypt with a top-down approach using the continuity equation in steady state. Emissions are expressed as the sum of a transport term and a sink term representing the three-body reaction comprising NO2 and hydroxyl radical (OH). This sink term requires information on the lifetime of NO2, which is calculated with the use of the CAMS near-real-time temperature and OH concentration fields. We compare this derived lifetime with the lifetime inferred from the fitting of NO2 line density profiles in large plumes with an exponentially modified Gaussian function. This comparison, which is conducted for different samples of NO2 patterns above the city of Riyadh, provides information on the reliability of the CAMS near-real-time OH concentration fields; it also provides some hint on the vertical levels that best represent typical pollution sources in industrial areas and megacities in the Middle East region. In Egypt, total emissions of NOx are dominated by the sink term, but they can be locally dominated by wind transport, especially along the Nile where human activities are concentrated. Megacities and industrial regions clearly appear as the largest sources of NOx emissions in the country. Our top-down model infers emissions with a marked annual variability. By looking at the spatial distribution of emissions at the scale of different cities with different industrial characteristics, it appears that this variability is consistent with national electricity consumption. We detect lower emissions on Fridays, which are inherent to the social norm of the country, and quantify the drop in emissions in 2020 due to the COVID-19 pandemic. Overall, our estimations of NOx emissions for Egypt are 7.0 % higher than the CAMS-GLOB-ANT_v4.2 inventory and significantly differ in terms of seasonality.
Published: 2022

16. Increased drought effects on the phenology of autumn leaf senescence

Author: Chaoyang Wu, Jie Peng, Philippe Ciais, Josep Peñuelas, Huanjiong Wang, Santiago Beguería, T. Andrew Black, Rachhpal S. Jassal, Xiaoyang Zhang, Wenping Yuan, Eryuan Liang, Xiaoyue Wang, Hao Hua, Ronggao Liu, Weimin Ju, Yongshuo H. Fu, Quansheng Ge, Chinese Academy of Sciences, National Natural Science Foundation of China, European Commission, Fundación Ramón Areces, Agencia Estatal de Investigación (España), Generalitat de Catalunya, Beguería, Santiago, 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), and This work was funded by the Strategic Priority Research Programme of the Chinese Academy of Sciences (XDA19040103), the National Natural Science Foundation of China (42125101) and the CAS Interdisciplinary Innovation Team (JCTD-2020-05). J.P. and P.C. were funded by European Research Council Synergy grant ERC-SyG-2013-610028 IMBALANCE-P. J.P. was also financially supported by the Fundación Ramon Areces grant ELEMENTAL-CLIMATE, the Spanish Government grant PID2019-110521GB-I00 and the Catalan Government grant SGR 2017-1005.
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Take urgent action to combat climate change and its impacts, date of foliar senescence, Terrestrial ecosystem, carbon storage, Environmental Science (miscellaneous), [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, season, climate, Social Sciences (miscellaneous)
Abstract: 10 pags.- 4 Figs. Under Licence CC BY 4.0, Global warming delays the autumn date of foliar senescence (DFS) in recent decades, with positive implications for growing season length and therefore global carbon storage. However, warming-associated drought, leading to water limitation, may conversely stimulate earlier DFS. Using ground observations since 1940s and 34 years of satellite greenness data (1982‒2015) over the Northern Hemisphere (>30° N), we show the increased impact of drought on DFS. Earlier DFS is linked to decreased precipitation under warming and weaker drought resistance associated with various plant functional traits. For example, isohydric plants with strict regulation of water status may drop leaves fast during droughts. We derive an improved set of phenology models based on this influence and project earlier DFS by the end of the century, particularly at high latitudes (>50° N). Our results limit uncertainties in the later end of plant growth with warming, aiding estimation of carbon uptake of terrestrial ecosystems., This work was funded by the Strategic Priority Research Programme of the Chinese Academy of Sciences (XDA19040103), the National Natural Science Foundation of China (42125101) and the CAS Interdisciplinary Innovation Team (JCTD-2020-05). J.P. and P.C. were funded by European Research Council Synergy grant ERC-SyG-2013-610028 IMBALANCE-P. J.P. was also financially supported by the Fundación Ramon Areces grant ELEMENTAL-CLIMATE, the Spanish Government grant 2013-610028 and the Catalan Government grant SGR 2017-1005.
Published: 2022

17. Tracking Hunter-Gatherer Impact on Vegetation in Last Interglacial and Holocene Europe

Author: Nikulina, Anastasia, Macdonald, Katharine, Scherjon, Fulco, A. Pearce, Elena, Davoli, Marco, Svenning, Jens-Christian, Vella, Emily, Gaillard, Marie-José, Zapolska, Anhelina, Arthur, Frank, Martinez, Alexandre, Hatlestad, Kailin, Mazier, Florence, Serge, Maria Antonia, Lindholm, Karl-Johan, Fyfe, Ralph, Renssen, Hans, Roche, Didier, Kluiving, Sjoerd, Roebroeks, Wil, Serge, Maria, Universiteit Leiden, Aarhus University [Aarhus], Uppsala University, Linnaeus University, Vrije Universiteit Amsterdam [Amsterdam] (VU), University of South-Eastern Norway (USN), Géographie de l'environnement (GEODE), Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Plymouth University, 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), Earth and Climate, CLUE+, Art and Culture, History, Antiquity, Earth Sciences, Amsterdam Sustainability Institute, Leiden University, Université Toulouse - Jean Jaurès (UT2J)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), 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)-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: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 010506 paleontology, Archeology, 010504 meteorology & atmospheric sciences, Holocene, 15. Life on land, Human-environment interaction, Mesolithic, Neanderthal, Last Interglacial, Hunter-gatherers, 01 natural sciences, Archaeology, 13. Climate action, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Arkeologi, 0105 earth and related environmental sciences
Abstract: We review palaeoenvironmental proxies and combinations of these relevant for understanding hunter-gatherer niche construction activities in pre-agricultural Europe. Our approach consists of two steps: (1) identify the possible range of hunter-gatherer impacts on landscapes based on ethnographic studies; (2) evaluate proxies possibly reflecting these impacts for both the Eemian (Last Interglacial, Middle Palaeolithic) and the Early–Middle Holocene (Mesolithic). We found these paleoenvironmental proxies were not able to unequivocally establish clear-cut differences between specific anthropogenic, climatic and megafaunal impacts for either time period in this area. We discuss case studies for both periods and show that published evidence for Mesolithic manipulation of landscapes is based on the interpretation of comparable data as available for the Last Interglacial. If one applies the ‘Mesolithic’ interpretation schemes to the Neanderthal record, three common niche construction activities can be hypothesised: vegetation burning, plant manipulation and impact on animal species presence and abundance. Our review suggests that as strong a case can be made for a Neanderthal impact on landscapes as for anthropogenic landscape changes during the Mesolithic, even though the Neanderthal evidence comes from only one high-resolution site complex. Further research should include attempts (e.g. by means of modelling studies) to establish whether hunter-gatherer impact on landscapes played out at a local level only versus at a larger scale during both time periods, while we also need to obtain comparative data on the population sizes of Last Interglacial and Holocene hunter-gatherers, as these are usually inferred to have differed significantly.
Published: 2022

18. Mechanisms for Extreme Precipitation Changes in a Tropical Archipelago

Author: Argüeso, Daniel, Luca, A. Di, Jourdain, Nicolas, Romero, R., Homar, V., University of the Balearic Islands (UIB), Université du Québec à Montréal = University of Québec in Montréal (UQAM), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), and Universidad Carlos III de Madrid [Madrid] (UC3M)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, Extreme precipitation, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climate Change, Convective parameterization, Convection-Permitting, Precipitation, Maritime Continent
Abstract: The Maritime Continent is one of the most challenging regions for atmospheric models. Processes that modulate deep convection are poorly represented in models, which affects their ability to simulate precipitation features accurately. Thus, future projections of precipitation over the region are prone to large uncertainties. One of the key players in modeling tropical precipitation is the convective representation, and hence convection-permitting experiments have contributed to improve aspects of precipitation in models. This improvement creates opportunities to explore the physical processes that govern rainfall in the Maritime Continent, as well as their role in a warming climate. Here, we examine the response to climate change of models with explicit and parameterized convection and how that reflects in precipitation changes. We focus on the intensification of spatial contrasts as precursors of changes in mean and extreme precipitation in the tropical archipelago. Our results show that the broad picture is similar in both model setups, where islands will undergo an increase in mean and extreme precipitation in a warmer climate and the ocean will see less rain. However, the magnitude and spatial structure of such changes, as well as the projection of rainfall percentiles, are different across model experiments. We suggest that while the primary effect of climate change is thermodynamical and it is similarly reproduced by both model configurations, dynamical effects are represented quite differently in explicit and parameterized convection experiments. In this study, we link such differences to horizontal and vertical spatial contrasts and how convective representations translate them into precipitation changes.
Published: 2022

19. Changes in productivity and intermediate circulation in the northern Indian Ocean since the last deglaciation: new insights from benthic foraminiferal Cd ∕ Ca records and benthic assemblage analyses

Author: Laetitia Licari, Frédéric Haurine, Sophie Sépulcre, Ruifang Ma, Zhaojie Yu, Christophe Colin, Franck Bassinot, Géosciences Paris Saclay (GEOPS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-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), 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), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Paléocéanographie (PALEOCEAN), Chinese Academy of Sciences [Qingdao], ANR-11-IDEX-0004,SUPER,Sorbonne Universités à Paris pour l'Enseignement et la Recherche(2011), and ANR-17-EURE-0006,IPSL-CGS,IPSL Climate graduate school(2017)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Monsoon of South Asia, Water mass, Global and Planetary Change, Stratigraphy, Paleontology, Oceanography, Productivity (ecology), Benthic zone, Deglaciation, 14. Life underwater, Stadial, Younger Dryas, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Geology, Holocene
Abstract: We have measured Cd/Ca ratios of several benthic foraminiferal species and studied benthic foraminiferal assemblages on two cores from the northern Indian Ocean (Arabian Sea and northern Bay of Bengal, BoB), in order to reconstruct variations in intermediate-water circulation and paleo-nutrient content since the last deglaciation. Intermediate water Cdw records estimated from the benthic Cd/Ca reflect past changes in surface productivity and/or intermediate–bottom-water ventilation. The benthic foraminiferal assemblages are consistent with the geochemical data. These results suggest that during the last deglaciation, Cdw variability was primarily driven by changes in intermediate-water properties, indicating an enhanced ventilation of intermediate–bottom water masses during both Heinrich Stadial 1 and the Younger Dryas (HS1 and YD, respectively). During the Holocene, however, surface primary productivity appears to have influenced Cdw more than intermediate water mass properties. This is evident during the early Holocene (from 10 to 6 cal ka) when benthic foraminiferal assemblages indicate that surface primary productivity was low, resulting in low intermediate-water Cdw at both sites. Then, from ∼ 5.2 to 2.4 cal ka, surface productivity increased markedly, causing a significant increase in the intermediate-water Cdw in the southeastern Arabian Sea and the northeastern BoB. The comparison of intermediate-water Cdw records with previous reconstructions of past Indian monsoon evolution during the Holocene suggests a direct control of intermediate-water Cdw by monsoon-induced changes in upper-water stratification and surface primary productivity.
Published: 2022

20. Coastal Zone Changes in West Africa: Challenges and Opportunities for Satellite Earth Observations

Author: Rafael Almar, Thomas Stieglitz, Kwasi Appeaning Addo, Kader Ba, Gregoire Abessolo Ondoa, Erwin W. J. Bergsma, Frédéric Bonou, Olusegun Dada, Donatus Angnuureng, Olivier Arino, 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), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Department of Earth Science [University of Ghana], University of Ghana, Université Cheikh Anta Diop [Dakar, Sénégal] (UCAD), Institut Universitaire de Technologie de Douala (IUT Douala), Université de Douala, IRHOB, Centre de Recherches Halieutiques et Océanologiques du Bénin [Cotonou] (CRHOB), Federal University of Technology of Akure (FUTA), University of Cape Coast [Ghana], and Agence Spatiale Européenne = European Space Agency (ESA)
Subjects: Coastal zone management, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Geophysics, Monitoring, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Geochemistry and Petrology, Vulnerability, Satellite Earth observations, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Coastal hazards
Abstract: The West African coastal population and ecosystems are increasingly exposed to a multitude of hazards. These are likely to be exacerbated by global climate change and direct impacts from local human activities. Our ability to understand coastal changes has been limited by an incomplete understanding of the processes and the difficulty of obtaining detailed data. Recent advances in satellite techniques have made it possible to obtain rich coastal data sets that provide a solid foundation for improving climate change adaptation strategies for humanity and increasing the resilience of ecosystems for sustainable development. In this article, we review West African coastal layout and current socio-environmental challenges together with key parameters that can be monitored and several coastal management programs that rely on satellite techniques to monitor indicators at the regional level. The social, technical and scientific problems and difficulties that hinder the interest of coastal practitioners and decision-makers to use the satellite data are identified. We provide a roadmap to precisely respond to these difficulties and on how an improved satellite earth observation strategy can better support future coastal zone management in West Africa.
Published: 2022

21. Global Tracking and Quantification of Oil and Gas Methane Emissions from Recurrent Sentinel-2 Imagery

Author: Thibaud Ehret, Aurélien De Truchis, Matthieu Mazzolini, Jean-Michel Morel, Alexandre d’Aspremont, Thomas Lauvaux, Riley Duren, Daniel Cusworth, Gabriele Facciolo, CB - Centre Borelli - UMR 9010 (CB), Service de Santé des Armées-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay)-Université Paris Cité (UPCité), Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay), Kayrros, Laboratoire de physique de l'ENS - ENS Paris (LPENS), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Département de Physique de l'ENS-PSL, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), 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), University of Arizona, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), The authors thank Omar Dhobb from Kayrros for his encouragement and support. Workpartly financed by Office of Naval research grant N00014-17-1-2552, DGA Astrid project'Filmer la Terre' no ANR-17-ASTR-0013-01, and MENRT. T. Lauvaux was supportedby the French research program 'Make Our Planet Great Again' (CNRS, project CIUDAD). Alexandre d’Aspremont is at CNRS & d´epartement d’informatique, Ecole normale ´sup´erieure, UMR CNRS 8548, 45 rue d’Ulm 75005 Paris, France, INRIA and PSL ResearchUniversity, and would like to acknowledge support from the ML and Optimisation jointresearch initiative with the fonds AXA pour la recherche and Kamet Ventures, a Googlefocused award, as well as funding by the French government under management of AgenceNationale de la Recherche as part of the 'Investissements d’avenir' program, reference ANR19-P3IA-0001 (PRAIRIE 3IA Institute, ANR-17-ASTR-0013,Filmer la Terre en relief,Filmer la Terre en relief : Reconstruction 3D et détection de changement(2017), ANR-19-P3IA-0001,PRAIRIE,PaRis Artificial Intelligence Research InstitutE(2019), Aptel, Florence, Filmer la Terre en relief : Reconstruction 3D et détection de changement - - Filmer la Terre en relief2017 - ANR-17-ASTR-0013 - ASTRID - VALID, and PaRis Artificial Intelligence Research InstitutE - - PRAIRIE2019 - ANR-19-P3IA-0001 - P3IA - VALID
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Physics - Atmospheric and Oceanic Physics, [SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric and Oceanic Physics (physics.ao-ph), FOS: Physical sciences, Environmental Chemistry, General Chemistry, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, [SDU.ENVI] Sciences of the Universe [physics]/Continental interfaces, environment
Abstract: Methane (CH4) emissions estimates from top-down studies over oil and gas basins have revealed systematic under-estimation of CH4 emissions in current national inventories. Sparse but extremely large amounts of CH4 from oil and gas production activities have been detected across the globe, resulting in a significant increase of the overall O&G contribution. However, attribution to specific facilities remains a major challenge unless high-resolution images provide the sufficient granularity within O&G basin. In this paper, we monitor known oil-and-gas infrastructures across the globe using recurrent Sentinel-2 imagery to detect and quantify more than 800 CH4 emissions. In combination with emissions estimates from airborne and Sentinel-5P measurements, we demonstrate the robustness of the fit to a power law from 0.1 tCH4/hr to 600 tCH4/hr. We conclude here that the prevalence of ultra-emitters (> 25tCH4/hr) detected globally by Sentinel-5P directly relates to emission occurrences below its detection threshold. Similar power law coefficients arise from several major oil and gas producers but noticeable differences in emissions magnitudes suggest large differences in maintenance practices and infrastructures across countries., Comment: Preprint version of https://pubs.acs.org/doi/abs/10.1021/acs.est.1c08575
Published: 2022

22. A non-stationary extreme-value approach for climate projection ensembles: application to snow loads in the French Alps

Author: Erwan Le Roux, Guillaume Evin, Nicolas Eckert, Juliette Blanchet, Samuel Morin, Erosion torrentielle neige et avalanches (UR ETGR (ETNA)), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Centre d'Etudes de la Neige (CEN), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [MATH.MATH-ST]Mathematics [math]/Statistics [math.ST], General Earth and Planetary Sciences
Abstract: Anticipating risks related to climate extremes often relies on the quantification of large return levels (values exceeded with small probability) from climate projection ensembles. Current approaches based on multi-model ensembles (MMEs) usually estimate return levels separately for each climate simulation of the MME. In contrast, using MME obtained with different combinations of general circulation model (GCM) and regional climate model (RCM), our approach estimates return levels together from the past observations and all GCM–RCM pairs, considering both historical and future periods. The proposed methodology seeks to provide estimates of projected return levels accounting for the variability of individual GCM–RCM trajectories, with a robust quantification of uncertainties. To this aim, we introduce a flexible non-stationary generalized extreme value (GEV) distribution that includes (i) piecewise linear functions to model the changes in the three GEV parameters and (ii) adjustment coefficients for the location and scale parameters to adjust the GEV distributions of the GCM–RCM pairs with respect to the GEV distribution of the past observations. Our application focuses on snow load at 1500 m elevation for the 23 massifs of the French Alps. Annual maxima are available for 20 adjusted GCM–RCM pairs from the EURO-CORDEX experiment under the scenario Representative Concentration Pathway (RCP) 8.5. Our results show with a model-as-truth experiment that at least two linear pieces should be considered for the piecewise linear functions. We also show, with a split-sample experiment, that eight massifs should consider adjustment coefficients. These two experiments help us select the GEV parameterizations for each massif. Finally, using these selected parameterizations, we find that the 50-year return level of snow load is projected to decrease in all massifs by −2.9 kN m−2 (−50 %) on average between 1986–2005 and 2080–2099 at 1500 m elevation and RCP8.5. This paper extends the recent idea to constrain climate projection ensembles using past observations to climate extremes.
Published: 2022

23. A interação entre emissões de vegetação e humana e seu efeito na qualidade do ar em São Paulo em um contexto de mudanças climáticas

Author: Ferreira de Brito, Joel, Oliveira, Amauri, Staudt, Michael, Souza, Silvia, Jaffrezo, Jean-Luc, Ynoue, Rita Yuri, Borbon, Agnès, Fornaro, Adalgiza, Centre for Energy and Environment (CERI EE - IMT Nord Europe), Ecole nationale supérieure Mines-Télécom Lille Douai (IMT Nord Europe), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Universidade de São Paulo = University of São Paulo (USP), Centre d’Ecologie Fonctionnelle et Evolutive (CEFE), Université Paul-Valéry - Montpellier 3 (UPVM)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG), Laboratoire de Météorologie Physique (LaMP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), ANR-20-CE01-0019,BIOMASPplus,Emissions biogéniques, évolution et impact dans la mégapole de São Paulo(2020), and ANR-11-LABX-0005,Cappa,Physiques et Chimie de l'Environnement Atmosphérique(2011)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere
Abstract: International audience
Published: 2023

24. Imprint of Mesoscale Eddies on Air-Sea Interaction in the Tropical Atlantic Ocean

Author: Aguedjou, Habib Micaël A., Chaigneau, Alexis, Dadou, Isabelle, Morel, Yves, Baloïtcha, Ezinvi, Da-Allada, Casimir, 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 Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Université d’Abomey-Calavi = University of Abomey Calavi (UAC), This work was supported by the Alti-ETAO and the SWOT-GG projects founded bythe French National Center for Space Studies (CNES) through the Ocean Surface Topography Sci-ence Team (OSTST) and supported by the French National Institute of Sciences of the Universe(INSU/CNRS). This work is also a contribution to the junior team 'SAFUME' (JEAI-SAFUME)associated with the French National Research Institute for Development (IRD) and to the EU H2020TRIATLAS project under grant agreement 817578. M. Aguedjou was supported by a PhD fellowshipfrom the IRD and the Cultural Action and Cooperation Service (SCAC) of the French Embassy inBenin during his PhD thesis and by the University of Toulouse (UT3) and the CNES during hispostdoctoral position., and European Project: 817578,TRIATLAS(2019)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, air–sea heat exchange, Mesoscale eddies, tropical Atlantic Ocean, Air-sea heat exchange, Satellite altimetry, mesoscale eddies, Precipitation, precipitation, satellite altimetry
Abstract: International audience; This study investigates the effect of mesoscale eddies on air–sea heat and fresh water exchange in the tropical Atlantic Ocean (TAO) using 8 years of satellite altimetry data, combined with sea surface temperature (SST), latent and sensible heat fluxes (LHF and SHF), infrared fluxes (IRF) and precipitation (PR) data. Results indicate that approximately ∼40% of cyclonic eddies contribute to warm SST anomalies, and ∼40% of anticyclonic eddies contribute to cold SST anomalies. Eddies were found to play a role in the variability in LHF, SHF and IRF, contributing 10–35% of their total variability, with the largest contributions observed beneath the intertropical convergence zone (ITCZ) and frontal SST areas. Composite analysis of SST and heat flux anomalies over eddies suggested that the anomalies created through horizontal advection processes may not significantly impact the overall LHF, SHF and IRF over eddies, contrary to vertical processes. Despite a lack of clear correlation between heat flux and PR anomalies over eddies in the TAO, significant correlations were found beneath the ITCZ, suggesting that eddies may impact both heat fluxes and PR in the ITCZ region. This study provides an original contribution to the understanding of the impact of ocean mesoscale eddies on the atmosphere in the TAO.
Published: 2023

25. Data-driven reconstruction of partially observed dynamical systems

Author: Pierre Tandeo, Pierre Ailliot, Florian Sévellec, Département Mathematical and Electrical Engineering (IMT Atlantique - MEE), IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Equipe Observations Signal & Environnement (Lab-STICC_OSE), Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT), Océan Dynamique Observations Analyse (ODYSSEY), Université de Bretagne Occidentale - UFR Sciences et Techniques (UBO UFR ST), Université de Brest (UBO)-Université de Brest (UBO)-Université de Rennes (UR)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-IMT Atlantique (IMT Atlantique), 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), RIKEN Center for Computational Science [Kobe] (RIKEN CCS), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Département de Mathématiques [Brest], Laboratoire de Mathématiques de Bretagne Atlantique (LMBA), Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie Physique et Spatiale (LOPS), and Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [STAT.ML]Statistics [stat]/Machine Learning [stat.ML], [MATH.MATH-ST]Mathematics [math]/Statistics [math.ST], [NLIN.NLIN-CD]Nonlinear Sciences [physics]/Chaotic Dynamics [nlin.CD], [STAT.ME]Statistics [stat]/Methodology [stat.ME]
Abstract: The state of the atmosphere, or of the ocean, cannot be exhaustively observed. Crucial parts might remain out of reach of proper monitoring. Also, defining the exact set of equations driving the atmosphere and ocean is virtually impossible because of their complexity. Hence, the goal of this paper is to obtain predictions of a partially observed dynamical system, without knowing the model equations. In this data-driven context, the article focuses on the Lorenz-63 system, where only the second and third components are observed, and access to the equations is not allowed. To account to those strong constraints, a combination of machine learning and data assimilation techniques is proposed. The key aspects are the following: the introduction of latent variables, a linear approximation of the dynamics, and a database that is updated iteratively, maximising the innovation likelihood. We find that the latent variables inferred by the procedure are related to the successive derivatives of the observed components of the dynamical system. The method is also able to reconstruct accurately the local dynamics of the partially observed system. Overall, the proposed methodology is simple, easy to code, and gives promising results, even in the case of small amounts of observations.
Published: 2023

26. Mid-21st century air quality at the urban scale under the influence of changed climate and emissions: case studies for Paris and Stockholm

Author: Myrto Valari, Magnuz Engardt, Robert Vautard, Gwendoline Lacressonnière, Konstantinos Markakis, Camilla Andersson, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), 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), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Swedish Meteorological and Hydrological Institute (SMHI), 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), Extrèmes : Statistiques, Impacts et Régionalisation (ESTIMR), 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), UN-HABITAT, 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: Atmospheric Science, Ozone, Meteorology, 010504 meteorology & atmospheric sciences, Health impact, Climate change, 010501 environmental sciences, Atmospheric sciences, 7. Clean energy, 01 natural sciences, lcsh:Chemistry, chemistry.chemical_compound, 11. Sustainability, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Air quality index, 0105 earth and related environmental sciences, Pollutant, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global warming, Miljövetenskap, lcsh:QC1-999, chemistry, lcsh:QD1-999, Homogeneous, 13. Climate action, [SDU]Sciences of the Universe [physics], Environmental science, Urban scale, lcsh:Physics, Environmental Sciences
Abstract: International audience; Ozone, PM10 and PM2.5 concentrations over Paris, France and Stockholm, Sweden were modeled at 4 and 1 \unit{km} horizontal resolutions respectively for the present and 2050 periods employing decade-long simulations. We account for large-scale global climate change (RCP-4.5) and fine resolution bottom-up emission projections developed by local experts and quantify their impact on future pollutant concentrations. Moreover, we identify biases related to the implementation of regional scale emission projections over the study areas by comparing modeled pollutant concentrations between the fine and coarse scale simulations. We show that over urban areas with major regional contribution (e.g., the city of Stockholm) the bias due to coarse emission inventory may be significant and lead to policy misclassification. Our results stress the need to better understand the mechanism of bias propagation across the modeling scales in order to design more successful local-scale strategies. We find that the impact of climate change is spatially homogeneous in both regions, implying strong regional influence. The climate benefit for ozone (daily average and maximum) is up to -5 % for Paris and -2 % for Stockholm city. The joined climate benefit on PM2.5 and PM10 in Paris is between -10 and -5 % while for Stockholm we observe mixed trends up to 3 % depending on season and size class. In Stockholm, emission mitigation leads to concentration reductions up to 15 % for daily average and maximum ozone and 20 % for PM and through a sensitivity analysis we show that this response is entirely due to changes in emissions at the regional scale. On the contrary, over the city of Paris (VOC-limited photochemical regime), local mitigation of NOx emissions increases future ozone concentrations due to ozone titration inhibition. This competing trend between the respective roles of emission and climate change, results in an increase in 2050 daily average ozone by 2.5 % in Paris. Climate and not emission change appears to be the most influential factor for maximum ozone concentration over the city of Paris, which may be particularly interesting in a health impact perspective.
Published: 2023

27. Shrinking of the Arabian Sea oxygen minimum zone with climate change projected with a downscaled model

Author: Vallivattathillam, Parvathi, Lachkar, Zouhair, Lévy, Marina, New York University [Abu Dhabi], NYU System (NYU), Processus et interactions de fine échelle océanique (PROTEO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, climate change, oxygen minimum zone, Arabian Sea, [SDE.MCG]Environmental Sciences/Global Changes, downscaling, ocean modeling, CMIP5, Ocean Engineering, Aquatic Science, Oceanography, Water Science and Technology
Abstract: In Arabian Sea (AS), land-locked northern boundary and strong seasonal productivity lead to the formation of one of the most intense open ocean Oxygen Minimum Zones (OMZs). Presence of this perennial OMZ has significant consequences on adjacent coastal fisheries and ecosystem. Simulations from CMIP5 suggest significant weakening of both monsoonal winds and productivity under high emission scenario. But the fate of AS OMZ in this scenario - whether it will expand or shrink - still remains elusive, mainly due to poor representation of extent and strength of AS OMZ in CMIP5 present-day simulations. To address this, we analyze the distribution of O2 in AS from a subset of three contrasted CMIP5 simulations, and complemented with a set of regional downscaled model experiments which we forced at surface and open boundaries using information from those three CMIP5 models. We tested two regional downscaling approaches - with and without correction of CMIP5 biases with respect to observations. Using a set of sensitivity experiments, we disentangle the contributions of local (atmospheric) forcing vs. remote (at the lateral boundaries) forcing in driving the future projected O2 changes. While CMIP5 projects either shrinking or expansion of the AS OMZ depending on the model, our downscaling experiments consistently project a shrinking of AS OMZ. We show that projected O2 changes in OMZ layer are affected by both local and remote processes. In the southern AS, the main response to climate change is oxygenation that originates from the boundaries, and hence downscalled and CMIP5 model responses are similar. In contrast, in northern AS, downscaling yields a substantial reduction in O2 projection discrepancies because of a minimal influence of remote forcing there leading to a stronger sensitivity to improved local physics and improved model representation of present-day conditions. We find that when corrected for present-day biases, projected deoxygenation in the northern AS is shallower. Our findings indicate the importance of downscaling of global models in regions where local forcing is dominant, and the need for correcting global model biases with respect to observations to reduce uncertainties in future O2 projections.
Published: 2023

28. 137 CS DESORPTION WITHIN AN ESTUARY: MODELLING AND EXPERIMENTS

Author: Radakovitch, Olivier, Delaval, Adrien, Duffa, Céline, Boyer, P., Flipo, Léonore, Coppin, Frédéric, Pairaud, Ivane, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Laboratoire de recherche sur les transferts des radionucléides dans les écosystèmes aquatiques (IRSN/PSE-ENV/SRTE/LRTA), Service de recherche sur les transferts et les effets des radionucléides sur les écosystèmes (IRSN/PSE-ENV/SRTE), Institut de Radioprotection et de Sûreté Nucléaire (IRSN)-Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Laboratoire de recherche sur les transferts des radionucléides dans les écosystèmes terrestres (IRSN/PSE-ENV/SRTE/LR2T), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), IRSN, EDF, Observatoire des sédiments du Rhône, and Rutgers Boskovic Institute
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Desorption kinetics, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Modelling & simulation, Radionuclides
Abstract: International audience; World nuclear production will increase sharply until 2035 and most of the planned reactors will be located along a river or by the sea. Any accidental release of radionuclides into the aquatic environment may thus reach the ocean, and the need to anticipate its consequences remains more significant than ever. IRSN has developed a chain of models for simulating the behavior of a dissolved 137Cs release on a river-sea continuum. Two independent models for the fluvial and marine environment were coupled using a box-model describing the hydrodynamic and geochemical estuarine processes affecting the 137Cs within an estuary. The study site was the Rhone River, bordered by 4 nuclear power plants and with a stratified estuary. The box model connects the flows from the river to the sea and takes into account desorption processes. Field data were used to represent hydrodynamic processes and for model validation. Laboratory experiments were performed to specify the role of salinity in the intensity and kinetics of 137Cs desorption. The salinity occurring when freshwaters meet marine systems induces a desorption of 137Cs from the particles, starting above 3-4 PSU and increasing inversely with the duration of the adsorption phase (ageing effect). A dynamic exchange model involving 2 sites of different affinities onto the particles was set to predict the distribution of 137Cs, and the role of ageing effect is also presently tested for other radionuclides (110Ag, 54Mn, 60Co) and preliminary results will be presented. This process will be critical in the event of very low river flow when a salt-wedge can go up the river for tens of kilometers. This can favor desorption of 40% of the particulate 137Cs, thus modifying its potential impact both in the coastal zone and in the terminal part of the river.
Published: 2023

29. L'Observatoire réunionnais de l'environnement nocturne. Discussion autour d’une démarche collective et transdisciplinaire

Author: Challéat, Samuel, Milian, Johan, Barré, Kévin, Bénos, Rémi, Delsaut, Mathieu, Farrugia, Nicolas, Franchomme, Magalie, Foglar, Hélène, Froidevaux, Jérémy, Godet, L., Guetté, Adrien, Jeanty, Patrick, Loose, David, Maisonobe, Marion, Michalczack, Johann, Morel, Béatrice, Morvan, Sylvain, Renaud, Matthieu, Riethmuller, Martin, Ronzani, Charles, Géographie de l'environnement (GEODE), Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Observatoire de l'environnement nocturne (OEN), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J), Laboratoire Dynamiques Sociales et Recomposition des Espaces (LADYSS), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris 8 Vincennes-Saint-Denis (UP8)-Université Paris Nanterre (UPN)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Centre d'Ecologie et des Sciences de la COnservation (CESCO), Muséum national d'Histoire naturelle (MNHN)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Energy Lab (ENERGY Lab), Université de La Réunion (UR), Equipe Better Representations for Artificial Intelligence (Lab_STICC_BRAIn), Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT), Département Mathematical and Electrical Engineering (IMT Atlantique - MEE), IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Territoires, Villes, Environnement & Société - ULR 4477 (TVES), Université du Littoral Côte d'Opale (ULCO)-Université de Lille, University of Stirling, Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN), Géographie-cités (GC (UMR_8504)), Université Paris 1 Panthéon-Sorbonne (UP1)-École des hautes études en sciences sociales (EHESS)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire Univers et Particules de Montpellier (LUPM), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Société d'études ornithologiques de la Réunion (SEOR), Ce projet a obtenu le soutien financier du CNRS à travers les programmes interdisciplinaires de la MITI, and Fédération de Recherche 'Environnement et Société' (FR CNRS 3041)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDV.EE]Life Sciences [q-bio]/Ecology, environment, interdisciplinarité, fenwar, [SHS.GEO]Humanities and Social Sciences/Geography, [SHS.ANTHRO-SE]Humanities and Social Sciences/Social Anthropology and ethnology, [SDE.ES]Environmental Sciences/Environmental and Society, La Réunion, ALAN, transdisciplinarité, Observatoire réunionnais de l'environnement nocturne, [SDE]Environmental Sciences, observatoire, participation, Observatoire environnement nocturne, fénoir, pollution lumineuse, environnement nocturne
Abstract: International audience; La notion d’environnement nocturne émerge à la suite de la requalification de la lumière artificielle nocturne en pollution lumineuse. Elle entend caractériser les systèmes humains et non humains fonctionnellement liés à l’obscurité. Contrairement à la notion de pollution lumineuse, elle oblige à penser conjointement les multiples enjeux du couple lumière artificielle/obscurité. En l’inscrivant dans le cadre d’analyse des systèmes socio-écologiques, nous faisons de l’environnement nocturne un objet de recherche à part entière apte à structurer une interdisciplinarité entre sciences de la nature et sciences humaines et sociales. C’est sur le territoire réunionnais que nous mettons cet objet relationnel à l’épreuve du monde réel, dans une démarche transdisciplinaire menée avec une multiplicité d’acteurs autour des enjeux d’aménagement que soulève la volonté de préservation holistique de la ressource obscurité. Du savoir à l’action, de la construction d’un objet de recherche à l’installation d’un dispositif collaboratif dédié à la production de connaissances scientifiques situées sur l’environnement nocturne et à l’accompagnement des acteurs locaux dans leurs démarches de préservation et de valorisation de l’obscurité, il s’agira bien sûr de rendre compte et discuter d’un processus de recherche hybride qui puise sa vitalité dans une interdisciplinarité radicale. Mais il s’agira également de témoigner de certaines difficultés que des différences de conceptions et de pratiques professionnelles peuvent poser dans la symétrisation des relations entre scientifiques et non scientifiques, entre chercheurs et autres acteurs sociaux.
Published: 2023

30. Regional and tele-connected impacts of the Tibetan Plateau surface darkening

Author: Shuchang Tang, Anouk Vlug, Shilong Piao, Fei Li, Tao Wang, Gerhard Krinner, Laurent Z. X. Li, Xuhui Wang, Guangjian Wu, Yue Li, Yuan Zhang, Xu Lian, Tandong Yao, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), 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: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Multidisciplinary, Atmosphere, Asia, Eastern, Temperature, General Physics and Astronomy, Water, General Chemistry, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Tibet, General Biochemistry, Genetics and Molecular Biology
Abstract: Despite knowledge of the presence of the Tibetan Plateau (TP) in reorganizing large-scale atmospheric circulation, it remains unclear how surface albedo darkening over TP will impact local glaciers and remote Asian monsoon systems. Here, we use a coupled land-atmosphere global climate model and a glacier model to address these questions. Under a high-emission scenario, TP surface albedo darkening will increase local temperature by 0.24 K by the end of this century. This warming will strengthen the elevated heat pump of TP, increasing South Asian monsoon precipitation while exacerbating the current “South Flood-North Drought” pattern over East Asia. The albedo darkening-induced climate change also leads to an accompanying TP glacier volume loss of 6.9%, which further increases to 25.2% at the equilibrium, with a notable loss in western TP. Our findings emphasize the importance of land-surface change responses in projecting future water resource availability, with important implications for water management policies.
Published: 2023

31. First archive of extensive N-fixation by volcanic lightning and implications for the prebiotic Earth

Author: Adeline Aroskay, Erwan Martin, Slimane Bekki, Joël Savarino, Jean-Luc Le Pennec, Abidin Temel, Nelida Manrique, Rigoberto Aguilar, Marco Rivera, Sophie Szopa, Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), STRATO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), 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), Hacettepe University = Hacettepe Üniversitesi, Instituto Geológico Minero y Metalúrgico (INGEMMET), Instituto Geofísico del Perú (IGP), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), 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: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology
Abstract: On Earth, most of the nitrogen (N) accessible for life is trapped in dinitrogen (N2), which is the most stable atmospheric molecule. In order to be metabolised by living organisms, N2 has to be converted into assimilable forms, also called fixed N. Nowadays, nearly all the N-fixation is achieved through biological and anthropogenic processes. However, in early environments of the Earth, before the emergence of life, N-fixation must have occurred via natural abiotic processes. Electrical discharges, including from thunderstorms and also lightning associated with volcanic eruptions is one of the most invoked processes. The occurence of volcanic lightning during explosive eruptions is frequent, and convincing laboratory experimentations support the role of this phenomenon, however no evidence of substantial N-fixation has been found in volcanic records. Here we report on the discovery of large amounts of nitrates in volcanic deposits from Neogene caldera-forming eruptions, which are well correlated with the concentrations of species directly emitted by volcanoes such as sulphur and chlorine. The multi-isotopic composition (δ18O, Δ17O) of the nitrates reveals that they originate from the atmospheric oxidation of nitrogen oxides formed by volcanic lightning that occur during the eruption. According to these volcanic nitrate records, our first estimates suggest that about 60 Tg of N can be fixed during a large explosive event. Our findings hint at a unique role potentially played by subaerial explosive eruptions in supplying essential ingredients for the emergence of life on Earth.
Published: 2023

32. Tides, Internal and Near-Inertial Waves in the Yermak Pass at the Entrance of the Atlantic Water to the Arctic Ocean

Author: Artana, Camila, Provost, Christine, Ferrari, Ramiro, Bricaud, Clément, Poli, Léa, Park, Young-Hyang, Instituto de Ciencias del Mar de Barcelona (ICM), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Austral, Boréal et Carbone (ABC), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), NOVELTIS LABEGE FRA, Partenaires IRSTEA, Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), 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), ANR-10-EQPX-0032,IAOOS,Système d'observation de la glace, de l'atmopshère et de l'océan en Arctique(2010), European Project: 603887,EC:FP7:ENV,FP7-ENV-2013-two-stage,ICE-ARC(2014), European Commission, and Agencia Estatal de Investigación (España)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Geophysics, Space and Planetary Science, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Oceanography
Abstract: 19 pages, 14 figures, 3 tables, 1 appendix, supporting information https://doi.org/10.1029/2022JC019082.-- Data Availability Statement: The raw and 50 hr high-pass filtered mooring data are available in the SEANOE data base: https://doi.org/10.17882/89349 and the 50 hr low-pass filtered mooring data at https://doi.org/10.17882/83214. The model outputs are available at: Copernicus Marine Environment Monitoring Service (CMEMS; http://marine.copernicus.eu), In the crucial region of the Yermak Plateau where warm Atlantic water enters the Arctic ocean, we examined high frequency variations in the Yermak Pass Branch over a 34 months-long mooring data set. The mooring was ice covered only half of the time with ice-free periods both in summer and winter. We investigated the contribution of residual tidal currents to the low frequency flow of Atlantic Water (AW) and high frequency variations in velocity shears possibly associated with internal waves. High resolution model simulations including tides show that diurnal tide forced an anticyclonic circulation around the Yermak Plateau. This residual circulation helps the northward penetration of the AW into the Arctic. Tides should be taken into account when examining low frequency AW inflow. High frequency variations in velocity shears are mainly concentrated in a broad band around 12 hr in the Yermak Pass. Anticyclonic eddies, observed during ice-free conditions, modulate the shear signal. Semi-diurnal internal stationary waves dominate high frequency variations in velocity shears. The stationary waves could result from the interaction of freely propagating semi-diurnal internal waves generated by diurnal barotropic tides on critical slopes around the plateau. The breaking of the stationary waves with short length scales possibly contribute to mixing of AW at the entrance to the Arctic, The field work was funded through the ANR EQUIPEX IAOOS project through ANR-10-EQX-32-01 grant and the ICE-ARC programme from the European Union 7th Framework Programme, Grant 603887.[...] Camila Artana acknowledges funding from the Spanish government (AEI) through the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S) and Lea Poli from a Sorbonne Université Ph.D. scolarship. This work is a contribution to H2020 Arctic Passion project, Grant 101003472
Published: 2023

33. Persistent anticyclonic conditions and climate change exacerbated the exceptional 2022 European-Mediterranean drought

Author: Davide Faranda, Salvatore Pascale, Burak Bulut, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), London Mathematical Laboratory, 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), Extrèmes : Statistiques, Impacts et Régionalisation (ESTIMR), 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), University of Bologna/Università di Bologna, European Project: 956396,EDIPI, European Project: 101003469,XAIDA, Faranda, Davide, Pascale, Salvatore, and Bulut, Burak
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Attribution, Drought, Renewable Energy, Sustainability and the Environment, Climate Change, [SDE.MCG]Environmental Sciences/Global Changes, Public Health, Environmental and Occupational Health, Drought -Climate Change -Attribution, drought, climate change, attribution, General Environmental Science
Abstract: A prolonged drought affected Western Europe and the Mediterranean region in the first nine months of 2022 producing large socio-ecological impacts. The role of anthropogenic climate change (ACC) in exacerbating this drought has been often invoked in the public debate, but the link between atmospheric circulation and ACC has not received much attention so far. Here we address this question by applying the method of circulation analogs, which allows us to identify atmospheric patterns in the period 1836-2021 very similar to those occurred in 2022. By comparing the circulation analogs when global warming was absent (1836-1915) with those occurred recently (1942-2021), and by excluding interannual and interdecadal variability as possible drivers, we identify the contribution of ACC. The 2022 drought was associated with an anticyclonic anomaly over Western Europe persistent over December 2021-August 2022. Circulation analogs of this atmospheric pattern in 1941-2021 feature 500 hPa geopotential height anomalies larger in both extent and magnitude, and higher temperatures at the surface, relative to those in 1836-1915. Both factors exacerbated the drought, by increasing the area affected and enhancing soil drying through evapotranspiration. While the occurrence of the atmospheric circulation associated with the 2022 drought has not become more frequent in recent decades, there is an increase of its interdecadal variability for which the influence of the Atlantic Multidecadal oscillation cannot be ruled-out.
Published: 2023

34. Hydrological modelling on atmospheric grids: using graphs of sub-grid elements to transport energy and water

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

35. Response of the sea surface temperature to heatwaves during the France 2022 meteorological summer

Author: Thibault Guinaldo, Aurore Voldoire, Robin Waldman, Stéphane Saux Picart, Hervé Roquet, Centre d’Etudes en Météorologie Satellitaire (CEMS), Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Groupe de Météorologie de Grande Échelle et Climat (GMGEC), Centre national de recherches météorologiques (CNRM), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Météo-France, EUMETSAT, and European Project: OSI SAF
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, General Medicine, [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology
Abstract: The summer of 2022 was memorable and record-breaking, ranking as the second hottest summer in France since 1900, with a seasonal surface air temperature average of 22.7 ∘C. In particular, France experienced multiple record-breaking heatwaves during the meteorological summer. As the main heat reservoir of the Earth system, the oceans are at the forefront of events of this magnitude which enhance oceanic disturbances such as marine heatwaves (MHWs). In this study, we investigate the sea surface temperature (SST) of French maritime basins using remotely sensed measurements to track the response of surface waters to the atmospheric heatwaves and determine the intensity of such feedback. Beyond the direct relationship between SSTs and surface air temperatures, we explore the leading atmospheric parameters affecting the upper-layer ocean heat budget. Despite some gaps in data availability, the SSTs measured during the meteorological summer of 2022 were record-breaking, the mean SST was between 1.3 and 2.6 ∘C above the long-term average (1982–2011), and the studied areas experienced between 4 and 22 d where the basin-averaged SSTs exceeded the maximum recorded basin-averaged SSTs from 1982 to 2011. We found a significant SST response during heatwave periods with maximum temperatures measured locally at 30.8 ∘C in the north-western Mediterranean Sea. Our results show that in August 2022 (31 July to 13 August), France experienced above-average surface solar radiation correlated with below-average total cloud cover and negative wind speed anomalies. Our attribution analysis based on a simplified mixed-layer heat budget highlights the critical role of ocean–atmosphere fluxes in initiating abnormally warm SSTs, while ocean mixing plays a crucial role in the cessation of such periods. We find that the 2 m temperatures and specific humidity that are consistently linked to the advection of warm and moist air masses are key variables across all the studied regions. Our results reveal that the influence of wind on heatwaves is variable and of secondary importance. Moreover, we observe that the incident solar radiation has a significant effect only on the Bay of Biscay (BB) and the English Channel (EC) areas. Our study findings are consistent with previous research and demonstrate the vulnerability of the Mediterranean Sea to the increasing frequency of extreme weather events resulting from climate change. Furthermore, our investigation reveals that the recurring heatwave episodes during the summer of 2022 had an undeniable impact on all the surveyed maritime areas in France. Our study therefore provides valuable insights into the complex mechanisms underlying the ocean–atmosphere interaction and demonstrates the need for an efficient and sustainable operational system combining polar-orbiting and geostationary satellites to monitor the alterations that threaten the oceans in the context of climate change.
Published: 2023

36. Opening Pandora's box: reducing global circulation model uncertainty in Australian simulations of the carbon cycle

Author: Lina Teckentrup, Martin G. De Kauwe, Gab Abramowitz, Andrew J. Pitman, Anna M. Ukkola, Sanaa Hobeichi, Bastien François, Benjamin Smith, 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), Australian Research Council, ARC: DE200100086, DP190101823, Climate Extremes, CLEX: CE170100023, and The research was funded by the ARC Centre of Excellence for Climate Extremes (CE170100023) and by the New South Wales Department of Planning, Industry and Environment. Martin G. De Kauwe and Andrew J. Pitman received support from the ARC Discovery Grant (DP190101823). Martin G. De Kauwe received support from the NSW Research Attraction and Acceleration Program (RAAP). Anna M. Ukkola received support from the Australian Research Council (DE200100086).
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Climate, Australia, General Earth and Planetary Sciences, GCM, Coupled Model Intercomparison Project 6 (CMIP6)
Abstract: Climate projections from global circulation models (GCMs), part of the Coupled Model Intercomparison Project 6 (CMIP6), are often employed to study the impact of future climate on ecosystems. However, especially at regional scales, climate projections display large biases in key forcing variables such as temperature and precipitation. These biases have been identified as a major source of uncertainty in carbon cycle projections, hampering predictive capacity. In this study, we open the proverbial Pandora's box and peer under the lid of strategies to tackle climate model ensemble uncertainty. We employ a dynamic global vegetation model (LPJ-GUESS) and force it with raw output from CMIP6 to assess the uncertainty associated with the choice of climate forcing. We then test different methods to either bias-correct or calculate ensemble averages over the original forcing data to reduce the climate-driven uncertainty in the regional projection of the Australian carbon cycle. We find that all bias correction methods reduce the bias of continental averages of steady-state carbon variables. Bias correction can improve model carbon outputs, but carbon pools are insensitive to the type of bias correction method applied for both individual GCMs and the arithmetic ensemble average across all corrected models. None of the bias correction methods consistently improve the change in simulated carbon over time compared to the target dataset, highlighting the need to account for temporal properties in correction or ensemble-averaging methods. Multivariate bias correction methods tend to reduce the uncertainty more than univariate approaches, although the overall magnitude is similar. Even after correcting the bias in the meteorological forcing dataset, the simulated vegetation distribution presents different patterns when different GCMs are used to drive LPJ-GUESS. Additionally, we found that both the weighted ensemble-averaging and random forest approach reduce the bias in total ecosystem carbon to almost zero, clearly outperforming the arithmetic ensemble-averaging method. The random forest approach also produces the results closest to the target dataset for the change in the total carbon pool, seasonal carbon fluxes, emphasizing that machine learning approaches are promising tools for future studies. This highlights that, where possible, an arithmetic ensemble average should be avoided. However, potential target datasets that would facilitate the application of machine learning approaches, i.e., that cover both the spatial and temporal domain required to derive a robust informed ensemble average, are sparse for ecosystem variables.
Published: 2023

37. The Z-2018 emissions inventory of COS in Europe: A semiquantitative multi-data-streams evaluation

Author: Sauveur Belviso, Isabelle Pison, Jean-Eudes Petit, Antoine Berchet, Marine Remaud, Leïla Simon, Michel Ramonet, Marc Delmotte, Victor Kazan, Camille Yver-Kwok, Morgan Lopez, 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), 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), Chimie Atmosphérique Expérimentale (CAE), and Modélisation INVerse pour les mesures atmosphériques et SATellitaires (SATINV)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, General Environmental Science
Abstract: International audience
Published: 2023

38. Sliding or Stumbling on the Staircase: Numerics of Ocean Circulation Along Piecewise‐Constant Coastlines

Author: Antoine‐Alexis Nasser, Gurvan Madec, Casimir de Lavergne, Laurent Debreu, Florian Lemarié, Eric Blayo, Mathematics and computing applied to oceanic and atmospheric flows (AIRSEA), Inria Grenoble - Rhône-Alpes, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Université Grenoble Alpes (UGA)-Laboratoire Jean Kuntzmann (LJK), Institut National de Recherche en Informatique et en Automatique (Inria)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Nucleus for European Modeling of the Ocean (NEMO R&D ), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, boundary current, idealized configuration, BATHYMETRY, topography, [SDU]Sciences of the Universe [physics], COASTAL OCEAN MODELING, ocean modeling, OCEANOGRAPHY, General Earth and Planetary Sciences, Environmental Chemistry, coastline, BOUNDARY CONDITION, TOPOGRAPHY EFFECT, [MATH.MATH-NA]Mathematics [math]/Numerical Analysis [math.NA]
Abstract: International audience; Coastlines in most ocean general circulation models are piecewise constant. Accurate representation of boundary currents along staircase-like coastlines is a long-standing issue in ocean modeling. Pioneering work by Adcroft and Marshall (1998, https://doi.org/10.3402/tellusa.v50i1.14514) revealed that artificial indentation of model coastlines, obtained by rotating the numerical mesh within an idealized square basin, generates a spurious form drag that slows down the circulation. Here, we revisit this problem and show how this spurious drag may be eliminated. First, we find that physical convergence to spatial resolution (i.e., the main characteristics of the flow are insensitive to the increase of the mesh resolution) allows simulations to become independent of the mesh orientation. An advection scheme with a wider stencil also reduces sensitivity to mesh orientation from coarser resolution. Second, we show that indented coastlines behave as straight and slippery shores when a true mirror boundary condition on the flow is imposed. This finding applies to both symmetric and rotational-divergence formulations of the stress tensor, and to both flux and vector-invariant forms of the equations. Finally, we demonstrate that the detachment of a vortex flowing past an outgoing corner of the coastline is missed with a free-slip (zero vorticity) condition at the corner. These results provide guidance for a better numerical treatment of coastlines (and isobaths) in ocean general circulation models.
Published: 2023

39. Diurnal variations in oxygen and nitrogen isotopes of atmospheric nitrogen dioxide and nitrate: implications for tracing NOx oxidation pathways and emission sources

Author: Sarah Albertin, Joël Savarino, Slimane Bekki, Albane Barbero, Roberto Grilli, Quentin Fournier, Irène Ventrillard, Nicolas Caillon, Kathy Law, Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interdisciplinaire de Physique [Saint Martin d’Hères] (LIPhy ), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), ANR-21-CE01-0017,CASPA,Sources d'aérosols et processus liés au climat dans l'Arctique(2021), ANR-10-LABX-0056,OSUG@2020,Innovative strategies for observing and modelling natural systems(2010), and ANR-15-IDEX-0002,UGA,IDEX UGA(2015)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere
Abstract: The oxygen (𝛥17O) and nitrogen (𝛿15N) isotopic compositions of atmospheric nitrate (NO3-) are widely used as tracers of its formation pathways, precursor (nitrogen oxides NOx = nitric oxide NO + nitrogen NO2) emission sources, and physico-chemical processing. However, the critical lack of observations on the multi-isotopic composition of NO2 maintains significant uncertainties regarding the links between the isotopic composition of NOx and NO3-, which may bias estimates of the NO3- formation processes and the distribution of sources. We report here on the first simultaneous atmospheric observations of 𝛥17O and 𝛿15N in NO2 and NO3-. The measurements were carried out at sub-daily (ca. 3 h) resolution over two non-consecutive days in an Alpine city in February 2021. Important diurnal variabilities are observed in both NO2 and NO3- multi-isotopic composition. 𝛥17O of NO2 and NO3- range from 19.6 to 40.8 ‰ and 18.7 to 26 ‰, respectively. During both daytime and nighttime, the variability of 𝛥17O(NO2) is mainly driven by the oxidation of NO by ozone, with a substantial contribution from peroxy radicals in the morning. NO3- local mass balance equations, constrained by observed 𝛥17O(NO2), suggest that during the first day of sampling NO3- was formed locally from the oxidation of NO2 by hydroxyl radicals during the day, and via heterogeneous hydrolysis of dinitrogen pentoxide during the night. For the second day, calculated and observed 𝛥17O(NO3-) do not match, particularly daytime values. The effects on 𝛥17O(NO3-) of a Saharan dust event that occurred during the second day and winter boundary layer dynamics are discussed. 𝛿15N of NO2 and NO3- ranged from -10.0 to 19.7 ‰ and -4.2 to 14.8 ‰, respectively. Consistent with theoretical predictions of N isotope fractionation, the important variability of 𝛿15N(NO2) is explained by significant post-emission equilibrium N fractionation. After accounting for this effect, vehicle exhaust is found to be the primary source of NOx emissions at the sampling site. 𝛿15N(NO3-) is closely linked to 𝛿15N(NO2) variability, which bring further evidence of fast and local processing, but uncertainties on current N fractionation factors during NO2 to NO3- conversion are underscored. Overall, this detailed investigation highlights the potential and the necessity to use 𝛥17O and 𝛿15N in NO2 and NO3- to trace quantitatively the sources and formation chemistry of NO3-, particularly in urban environments in winter.
Published: 2023

40. Was the 137Cs contained in Saharan dust deposited across Europe in March 2022 emitted by French nuclear tests in Algeria?

Author: Olivier Evrard, Octave Bryskere, Charlotte Skonieczny, Anthony Foucher, Rémi Bizeul, Thomas Chalaux Clergue, Jean-Sébastien Barbier, Jean-Eudes Petit, José A. Corcho‑Alvarado, Stefan Röllin, Pierre-Alexis Chaboche, Germán Orizaola, 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), Géochimie Des Impacts (GEDI), 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), Géosciences Paris Saclay (GEOPS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Chimie Atmosphérique Expérimentale (CAE), Spiez Laboratory, Federal Office for Civil Protection, Fukushima University [Fukushima, Japan], Universidad de Oviedo [Oviedo], and ANR-17-EURE-0006,IPSL-CGS,IPSL Climate graduate school(2017)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDE]Environmental Sciences, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDV.SA.SDS]Life Sciences [q-bio]/Agricultural sciences/Soil study, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, [CHIM.RADIO]Chemical Sciences/Radiochemistry, Panoply
Abstract: Air masses loaded with mineral dust and originating from the Sahara arrive frequently in Europe, which has multiple impacts on global and regional cycles. However, the occurrence of these processes may further accelerate in the future in response to climate change, and more knowledge is therefore required on the characteristics of the particles transported during these massive dust transport and deposition episodes. Furthermore, questions arise regarding the content of this dust in radionuclides, in relationship with the atmospheric nuclear bomb testing conducted around the world between the 1950s and the 1970s in general, and those tests conducted by France in the Sahara in the early 1960s in particular.The Saharan dust episode that took place from 13th to 16th March 2022 led to the occurrence of dense dust deposition across multiple European countries, which raised concerns among the population regarding the potential radioactivity content of this dust. To address this question with a representative sample set, a participative science campaign to collect dust across Europe was launched on Twitter on 17th March 2022. Thanks to this initiative, 110 dust samples could be collected along a transect from Southern Spain to Austria.This unique sample bank was regrouped at University Paris-Saclay, France, to conduct a set of physico-chemical analyses on a selection or on the totality of these dust samples including particle size, colourimetry, mineralogy and fallout radionuclides.Backward trajectories of air masses that have led to these deposits were calculated, and this analysis confirm their potential origin from Algeria. 137Cs was detected in all dust samples, with variable activity concentrations. A strong relationship was found between the particle size of the analysed particles and the 137Cs activity concentrations, which is consistent with the literature on this topic. Particle size was found to decrease with increasing distances from the source. The colour and mineralogy analyses demonstrated that the dust collected in Austria showed different properties than those samples collected in Spain, France, Luxembourg and Germany, which likely indicates that this material did not fully consist of Saharan dust deposited during the March 2022 episode. Accordingly, the following interpretations did not take the properties of Austrian dust into account.The mineralogical analyses confirmed the potential origin of the dust from the Maghreb region, including a vast area in Southern Morocco and Southern Algeria. In contrast, the analysis of plutonium isotopic ratios (240Pu/239Pu) and 137Cs/239+240Pu activity ratios, which provide diagnosis tools to investigate the source of artificial radionuclides, in a selection of dust samples collected between Southern Spain and Luxembourg showed that the dust signature was consistent with that of the global fallout largely dominated by the nuclear tests conducted by the USA and the Soviet Union. The 137Cs contained in the dust transported and deposited during this episode was therefore very likely not associated with the French nuclear tests conducted in the early 1960s in Sahara.In the future, elemental geochemistry analyses will provide additional information on their source provenance. All results will also be published in open-access database and disseminated to the public.
Published: 2023

41. Near-real-time detection of unexpected atmospheric events using principal component analysis on the Infrared Atmospheric Sounding Interferometer (IASI) radiances

Author: Adrien Vu Van, Anne Boynard, Pascal Prunet, Dominique Jolivet, Olivier Lezeaux, Patrice Henry, Claude Camy-Peyret, Lieven Clarisse, Bruno Franco, Pierre-François Coheur, Cathy Clerbaux, TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Sté SPASCIA, HYGEOS (SARL), Centre National d'Études Spatiales [Toulouse] (CNES), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Spectroscopy, Quantum Chemistry and Atmospheric Remote Sensing (SQUARES), and Université libre de Bruxelles (ULB)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science
Abstract: The three Infrared Atmospheric Sounding Interferometer (IASI) instruments on board the Metop family of satellites have been sounding the atmospheric composition since 2006. More than 30 atmospheric gases can be measured from the IASI radiance spectra, allowing the improvement of weather forecasting and the monitoring of atmospheric chemistry and climate variables. The early detection of extreme events such as fires, pollution episodes, volcanic eruptions, or industrial releases is key to take safety measures to protect the inhabitants and the environment in the impacted areas. With its near-real-time observations and good horizontal coverage, IASI can contribute to the series of monitoring systems for the systematic and continuous detection of exceptional atmospheric events in order to support operational decisions. In this paper, we describe a new approach to the near-real-time detection and characterization of unexpected events, which relies on the principal component analysis (PCA) of IASI radiance spectra. By analyzing both the IASI raw and compressed spectra, we applied a PCA-granule-based method on various past, well-documented extreme events such as volcanic eruptions, fires, anthropogenic pollution, and industrial accidents. We demonstrate that the method is well suited to the detection of spectral signatures for reactive and weakly absorbing gases, even for sporadic events. Consistent long-term records are also generated for fire and volcanic events from the available IASI/Metop-B data record. The method is running continuously, delivering email alerts on a routine basis, using the near-real-time IASI L1C radiance data. It is planned to be used as an online tool for the early and automatic detection of extreme events, which was not done before.
Published: 2023

42. Deriving composition-dependent aerosol absorption, scattering and extinction mass efficiencies from multi-annual high time resolution observations in Northern France

Author: A. Velazquez-Garcia, S. Crumeyrolle, J.F. de Brito, E. Tison, E. Bourrianne, I. Chiapello, V. Riffault, Centre for Energy and Environment (CERI EE - IMT Nord Europe), Ecole nationale supérieure Mines-Télécom Lille Douai (IMT Nord Europe), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Laboratoire d’Optique Atmosphérique - UMR 8518 (LOA), and Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, General Environmental Science
Abstract: International audience
Published: 2023

43. New insights on the 7Be cycle in the ocean

Author: M. Grenier, P. van Beek, P. Lerner, V. Sanial, M. Souhaut, Marion Lagarde, O. Marchal, J.L. Reyss, 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), NASA Goddard Institute for Space Studies (GISS), NASA Goddard Space Flight Center (GSFC), 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)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Woods Hole Oceanographic Institution (WHOI), 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), Océan et Interfaces (OCEANIS), 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: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Aquatic Science, Oceanography
Abstract: International audience
Published: 2023

44. Qu'est-ce qui contrôle les variations à méso-échelle de la composition isotopique de l'eau dans les cyclones tropicaux et les lignes de grain? Simulations avec un modèle résolvant les nuages en équilibre radiatif-convectif

Author: Camille Risi, Caroline Muller, Françoise Vimeux, Peter Blossey, Grégoire Védeau, Clarisse Dufaux, Sophie Abramian, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Hydrosciences Montpellier (HSM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), 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), and University of Washington [Seattle]
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, General Earth and Planetary Sciences, Environmental Chemistry, [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology
Abstract: International audience; Water isotopes are tracers of convective processes and are often used as proxies for past precipitation. These applications require a better understanding of the impact of convective processes on the isotopic composition of water vapor and precipitation. One way to advance this understanding is to analyze the isotopic mesoscale variations during organized convective systems such as tropical cyclones or squall lines. The goal of this study is to understand these isotopic mesoscale variations with particular attention to isotopic signals in near-surface vapor and precipitation that may be present in observations and in paleoclimate proxies. With this aim, we run cloud resolving model simulations in radiative-convective equilibrium in which rotation or wind shear is added, allowing us to simulate tropical cyclones or squall lines. The simulations capture the robust aspects of mesoscale isotopic variations in observed tropical cyclones and squall lines. We interpret these variations using a simple water budget model for the sub-cloud layer of different parts of the domain. We find that rain evaporation and rain-vapor diffusive exchanges are the main drivers of isotopic depletion within tropical cyclones and squall lines. Horizontal advection spreads isotopic anomalies, thus reshaping the mesoscale isotopic pattern. This study contributes to our understanding of mesoscale isotopic variability and provides physical arguments supporting the interpretation of paleoclimate isotopic archives in tropical regions in terms of past cyclonic activity.
Published: 2023

45. Impact of Synoptic Wind Intensification and Relaxation on the Dynamics and Heat Budget of the South Senegalese Upwelling Sector

Author: Pierre Chabert, Xavier Capet, Vincent Echevin, Alban Lazar, Christophe Hourdin, Siny Ndoye, Processus et interactions de fine échelle océanique (PROTEO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Océan et variabilité du climat (VARCLIM), Université Amadou Mahtar Mbow (UAM), ANR-18-CE32-0009,SOLAB,Interactions planctoniques, facteurs environnementaux et conséquences biologique/géochimiques dans le laboratoire côtier sud-Sénégalais(2018), and European Project: 603521,EC:FP7:ENV,FP7-ENV-2013-two-stage,PREFACE(2013)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Oceanography
Abstract: In addition to their well-known seasonal cycle, eastern boundary upwelling systems (EBUS) undergo modulation on shorter synoptic to intraseasonal time scales. Energetic intensifications and relaxations of upwelling-favorable winds with 5–10-day typical time scales can impact the EBUS dynamics and biogeochemical functioning. In this work the dynamical effects of wind-forced synoptic fluctuations on the South Senegalese Upwelling Sector (SSUS) are characterized. The region geomorphology is unique with its wide continental shelf and a major coastline discontinuity at its northern edge. The ocean response to synoptic events is explored using a modeling framework that involves applying idealized synoptic wind intensification or relaxation to a five-member climatological SSUS ensemble run. Model evaluation against sparse midshelf in situ observations indicates qualitative agreement in terms of synoptic variability of temperature, stratification, and ocean currents, despite a moderate but systematic bias in current intensity. Modeled synoptic wind and heat flux fluctuations produce clear modulations of all dynamical variables with robust SSUS-scale and mesoscale spatial patterns. A mixed layer heat budget analysis is performed over the continental shelf to uncover the dominant processes involved in SSUS synoptic variability. Modulations of horizontal advection and atmospheric forcing are the leading-order drivers of heat changes during either wind intensification or relaxation while vertical dynamics is of primary importance only in a very localized area. Also, modest asymmetries in the oceanic responses to upwelling intensification and relaxation are only identified for meridional velocities. This brings partial support to the hypothesis that synoptic variability has a modest net effect on the climatological state and functioning of upwelling systems dynamics.
Published: 2023

46. 3D landscape evolution reconstruction of the Magdalenian Roc-aux-Sorciers site (Vienne, France)

Author: Kim Genuite, Geneviève Pinçon, Jean-Jacques Delannoy, Oscar Fuentes, Stéphane Jaillet, Nadine Tisnérat-Laborde, Hélène Valladas, Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-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), Géochrononologie Traceurs Archéométrie (GEOTRAC), 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: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Archeology
Published: 2023

47. Trade‐offs and synergies between ecosystem productivity and stability in temperate grasslands

Author: Lucie Mahaut, Philippe Choler, Pierre Denelle, Eric Garnier, Wilfried Thuiller, Jens Kattge, Servane Lemauviel‐Lavenant, Sandra Lavorel, François Munoz, Delphine Renard, Josep M. Serra‐Diaz, Nicolas Viovy, Cyrille Violle, Centre d’Ecologie Fonctionnelle et Evolutive (CEFE), Université Paul-Valéry - Montpellier 3 (UPVM)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut Agro Montpellier, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université de Montpellier (UM), Laboratoire d'Ecologie Alpine (LECA ), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Department of Biodiversity, Macroecology and Biogeography, Georg-August-University = Georg-August-Universität Göttingen, Max Planck Institute for Biogeochemistry (MPI-BGC), Max-Planck-Gesellschaft, 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 des Surfaces et Interfaces Continentales (MOSAIC), 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: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, Ecology, Ecology, Evolution, Behavior and Systematics
Abstract: Aim: It is crucial to monitor how the productivity of grasslands varies with its temporal stability for management of these ecosystems. However, identifying the direction of the productivity-stability relationship remains challenging because ecological stability has multiple components that can display neutral, positive or negative covariations. Furthermore, evidence suggests that the direction of the productivity-stability relationship depends on the biotic interactions and abiotic conditions that underlie ecosystem productivity and stability. We decipher the relationships between grassland productivity and two components of its stability in four habitat types with contrasting environments and flora.
Published: 2023

48. Description and evaluation of the tropospheric aerosol scheme in the Integrated Forecasting System (IFS-AER, cycle 47R1) of ECMWF

Author: Zak Kipling, Martine Michou, Johannes Flemming, Pierre Nabat, Vincent-Henri Peuch, Richard Engelen, Samuel Remy, Melanie Ades, Vincent Huijnen, Groupe de Météorologie de Grande Échelle et Climat (GMGEC), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
Subjects: High surface, Atmosphere, Tropospheric aerosol, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Medium range, General Medicine, Surface concentration, Particulates, Atmospheric sciences, Aerosol
Abstract: This article describes the Integrated Forecasting System aerosol scheme (IFS-AER) used operationally in the IFS cycle 47R1, which was operated by the European Centre for Medium Range Weather Forecasts (ECMWF) in the framework of the Copernicus Atmospheric Monitoring Services (CAMS). It represents an update of the Rémy et al. (2019) article, which described cycle 45R1 of IFS-AER in detail. Here, we detail only the parameterisations of sources and sinks that have been updated since cycle 45R1, as well as recent changes in the configuration used operationally within CAMS. Compared to cycle 45R1, a greater integration of aerosol and chemistry has been achieved. Primary aerosol sources have been updated, with the implementation of new dust and sea salt aerosol emission schemes. New dry and wet deposition parameterisations have also been implemented. Sulfate production rates are now provided by the global chemistry component of IFS. This paper aims to describe most of the updates that have been implemented since cycle 45R1, not just the ones that are used operationally in cycle 47R1; components that are not used operationally will be clearly flagged. Cycle 47R1 of IFS-AER has been evaluated against a wide range of surface and total column observations. The final simulated products, such as particulate matter (PM) and aerosol optical depth (AOD), generally show a significant improvement in skill scores compared to results obtained with cycle 45R1. Similarly, the simulated surface concentration of sulfate, organic matter and sea salt aerosol are improved by cycle 47R1 compared to cycle 45R1. Some biases persist, such as the surface concentrations of nitrate and organic matter being simulated too high. The new wet and dry deposition schemes that have been implemented into cycle 47R1 have a mostly positive impact on simulated AOD, PM and speciated aerosol surface concentration.
Published: 2022

49. Sulfur Isotope Anomalies (Δ33S) in Urban Air Pollution Linked to Mineral-Dust-Associated Sulfate

Author: Sanjeev Dasari, Guillaume Paris, Bruna Saar, Qiaomin Pei, Zhiyuan Cong, David Widory, Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Université du Québec à Montréal = University of Québec in Montréal (UQAM), Institute of Tibetan Plateau Research, Chinese of Academy of Sciences, Chinese Academy of Sciences, Universite du Quebec a Montreal, and French National CNRS-INSU program LEFE (Les Enveloppes Fluides et l'Environnement)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Ecology, Air Pollution, Health, Toxicology and Mutagenesis, Environmental Chemistry, Sulfur Mass-Independent Fractionation (S-MIF), Particulate Matter, Model-Observation Reconciliation, [CHIM.OTHE]Chemical Sciences/Other, Pollution, Waste Management and Disposal, UV radiation, Water Science and Technology
Abstract: International audience; Sulfur isotope analysis provides a unique probe for source-specific information and certain atmospheric reactions. Globally, atmospheric aerosols in urban locations exhibit significant sulfur mass-independent fractionation (i.e., S-MIF, Δ33S ≠ 0). The origin(s) of these S-MIF anomalies remains unclear, thereby limiting the interpretation and/or application of such signals. Here, we conducted dual-isotope (Δ33S and δ34S) fingerprinting of sulfate aerosols from summertime megacity Delhi in south Asia. A shift toward concomitantly high Δ33S (from 0.2‰ to 0.5‰) and low δ34S (from 5‰ to 1‰) values was observed with the influx of mineral dust. The Fe:Al ratio showed significant correlations with both sulfate loadings (R2 = 0.84) and Δ33S signatures (R2 = 0.77). Contrary to the prevailing paradigm, this observational evidence suggests that mineral-dust-associated sulfate exhibits S-MIF anomalies. Atmospheric processing of mineral dust plausibly leads to the production of these anomalies. Our evaluation suggests that an inherent mechanism(s) remains elusive. Although hindered by end-member uncertainties, we show that S-MIF signals can be source apportioned to quantitatively constrain the fraction of mineral-dust-associated sulfate in urban locations. The influx of mineral-dust-associated sulfate can influence urban air pollution affecting air quality and/or human health and as such requires monitoring. Urban Δ33S signals can therefore be used to trace this sulfate fraction, thereby improving our understanding of sulfate aerosol dynamics.
Published: 2022

50. Automatic recognition of flow cytometric phytoplankton functional groups using convolutional neural networks

Author: Robin Fuchs, Melilotus Thyssen, Véronique Creach, Mathilde Dugenne, Lloyd Izard, Marie Latimier, Arnaud Louchart, Pierre Marrec, Machteld Rijkeboer, Gérald Grégori, Denys Pommeret, Institut de Mathématiques de Marseille (I2M), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), 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)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Centre for Environment, Fisheries and Aquaculture Science [Lowestoft] (CEFAS), University of Hawaii, Processus et interactions de fine échelle océanique (PROTEO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Dynamiques des Écosystèmes Côtiers (DYNECO), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Stazione Zoologica Anton Dohrn (SZN), Graduate School of Oceanography [Narragansett], University of Rhode Island (URI), Laboratoire de Sciences Actuarielle et Financière (SAF), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, and European Project: 1166-39417,FEDER
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Ocean Engineering, ComputingMilieux_MISCELLANEOUS
Abstract: The variability of phytoplankton distribution has been unraveled by high-frequency measurements. Such a resolution can be approached by automated pulse-shape recording flow cytometry (AFCM) operating at hourly sampling resolution. AFCM records morphological and physiological traits as single-cell optical pulse shapes that can be used to classify cells into phytoplankton functional groups (PFGs). However, the associated manual post-processing of the data coupled with the increasing size and number of datasets is time-consuming and error-prone. Machine learning models are increasingly used to run automatic classification. Yet, most of the existing methods either present a long training process, need to manually design features from the raw optical pulse shapes, or are dedicated to images only. In this study, we present a convolutional neural network (CNN) to classify several PFGs using AFCM pulse shapes. The uncertainties of manual classification were first estimated by comparing experts' recognition of six PFGs. Consensual particles from the manual PFG classification were used to train and validate the CNN. The CNN obtained competitive performances compared to other models used in the literature and remained robust across several sampling areas, and instrumental hardware and settings. Finally, we assessed the ability of this classifier to predict phytoplankton counts at a Mediterranean coastal station and from a cruise in the South-West Indian Ocean, providing a comparison with the manual classification over 3-month periods and a 2h frequency. These promising results strengthen the near real-time observation of PFGs, especially required with the increasing use of AFCM in monitoring research programs.
Published: 2022

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