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6,031 results on '"Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)"'

1. Intermodel Spread of Historical Indian Monsoon Rainfall Change in CMIP6: The Role of the Tropical Pacific Mean State

Author: Guilbert, Marcellin, Terray, Pascal, Mignot, Juliette, Océan et variabilité du climat (VARCLIM), 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), ANR-18-MPGA-0001,ARCHANGE,Changement climatique et Arctique et circulation océanique globale(2018), and ANR-19-JPOC-0003,ROADMAP,The Role of ocean dynamics and Ocean-Atmosphere interactions in Driving cliMAte variations and future Projections of impact-relevant extreme events(2019)
Subjects: Atmospheric Science, [SDU]Sciences of the Universe [physics]
Abstract: Robust projections of the Indian summer monsoon rainfall (ISMR) are critical as it provides 80% of the annual precipitation to more than 1 billion people who are very vulnerable to climate change. However, even over the historical period, state-of-the-art climate models have difficulties in reproducing the observed ISMR trends and are affected by a large intermodel spread, which questions the reliability of ISMR projections. Such uncertainty could come from internal variability or model biases. Here, we study the impact of the latter on the historical forced change of ISMR in 34 models from CMIP6. First, we show that models’ biases over India do not significantly impact how they simulate the historical change of ISMR. However, we do find statistically significant relationships between ISMR historical forced changes and remote rainfall and temperature biases within the tropics by using a maximum covariance analysis (MCA). Our results highlight the key role of tropical Pacific sea surface temperature (SST) mean state biases as an important source of intermodel spread in the ISMR change. The physical mechanisms underlying these statistical relationships between ISMR change and the intermodel spread of Pacific SST biases are finally explored. We found that models having El Niño/La Niña–like mean SST bias in the Pacific tend to exhibit El Niño/La Niña–like changes over the historical period, impacting ISMR through a shift in the Walker circulation and Rossby wave propagation across the Pacific.
Published: 2023

2. Mbi Crater (Cameroon) illustrates the relations between mountain and lowland forests over the past 15,000 years in western equatorial Africa

Author: Kenji Izumi, Gaston Achoundong, Anne-Marie Lézine, Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Variabilité à long terme du climat de l'océan (VALCO), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), School of Geographical Sciences [Bristol], University of Bristol [Bristol], Institut de Recherche Agricole pour le Développement [Yaoundé] (IRAD), ANR-06-BDIV-0014,IFORA,Les îles forestières africaines : modèles d'une nouvelle approche de la dynamique de structuration de la biodiversité(2006), ANR-09-PEXT-0001,C3A,Et si la 6ème extinction avait déjà eu lieu ? Causes et Conséquences de la dernière grande ' Crise ' environnementale (3000 ans BP) en Afrique équatoriale atlantique.(2009), ANR-15-MASC-0003,VULPES,VULnerability of Populations under Extreme Scenarios(2015), 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: 010506 paleontology, geography.geographical_feature_category, Biome, Biodiversity, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Climate change, Ecotone, Vegetation, 15. Life on land, 010502 geochemistry & geophysics, 01 natural sciences, Grassland, Geography, 13. Climate action, 14. Life underwater, Physical geography, Younger Dryas, ComputingMilieux_MISCELLANEOUS, Sea level, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract: Pollen-based vegetation, biodiversity, and biome reconstructions over the last 15,500 years from sediment core data at Mbi Crater in the Cameroon highlands (6.089273° N, 10.348549° E; 2015 m above sea level) are used to discuss the behavior of the lower edge of the Afromontane forest facing climate change. The data reveal that the post-glacial forest change gradually happened at Mbi and that the forest-wooded grassland ecotone was highly influenced by the climate variability related to the North Atlantic. The forest disruption and diversity loss intermittently occurred over the whole period, and their vegetation changes temporally match dry-cold events at the northern latitudes during the Younger Dryas, at 9.5–9.1 ka, 8.6–8.0 ka, 6.7–6.0 ka, 3.2 ka, and during the Little Ice Age (LIA). During the LIA, the mountain forest was subject to unprecedented levels of disturbance at all altitudes, unlike the seasonal lowland forests, which appears to have been only marginally affected.
Published: 2023

3. Seasonal and habitat-based variations in vertical export of biogenic sea-ice proxies in Hudson Bay

Author: Tiia Luostarinen, Kaarina Weckström, Jens Ehn, Michelle Kamula, Amanda Burson, Aura Diaz, Guillaume Massé, Suzanne McGowan, Zou Zou Kuzyk, Maija Heikkilä, Helsinki Institute of Sustainability Science (HELSUS), Faculty of Biological and Environmental Sciences [Helsinki], Helsingin yliopisto = Helsingfors universitet = University of Helsinki-Helsingin yliopisto = Helsingfors universitet = University of Helsinki, Helsingin yliopisto = Helsingfors universitet = University of Helsinki, Geological Survey of Denmark and Greenland (GEUS), Centre for Earth Observation Science [Winnipeg], University of Manitoba [Winnipeg], British Antarctic Survey (BAS), Natural Environment Research Council (NERC), University of Nottingham, UK (UON), Variabilité de l'Océan et de la Glace de mer (VOG), 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), Netherlands Institute of Ecology (NIOO-KNAW), Ecosystems and Environment Research Programme, Environmental Change Research Unit (ECRU), and Aquatic Ecology (AqE)
Subjects: Diatoms, Canada, Dinoflagellate cysts, Quebec, Fresh-water, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Biomarker, North-atlantic, 1181 Ecology, evolutionary biology, General Earth and Planetary Sciences, Variability, Manitounuk sound, Late quaternary, General Environmental Science
Abstract: Despite their wide use in past sea-ice reconstructions, the seasonal, habitat and species-based sources of sedimentary sea-ice proxies are poorly understood. Here, we conduct direct observations of the community composition of diatoms, dinoflagellate cysts and highly branched isoprenoid lipids within the sea ice, water column, sediment traps and sediment surface in the Belcher Islands Archipelago, Hudson Bay throughout spring 2019. We find that Arctic diatom and dinoflagellate cysts species commonly used as sea-ice proxies appear to be only indirectly linked to sea-ice conditions, and that the sediment assemblages of these groups overrepresent summertime pelagic blooms. Species contributing to the diverse sea-ice diatom communities are rare in the sediment. Dinoflagellate cysts form a typical Arctic assemblage in the sediment, although they are virtually absent in the sea ice and water column in spring. We also find that certain highly branched isoprenoid lipids that were previously considered indicators of open water, can be produced in sea-ice. We conclude that contextual knowledge and a multiproxy approach are necessary in reconstruction, encouraging further studies on the sources and controls of sea-ice proxy production in different geographic areas. Sedimentary assemblages of biogenic sea-ice proxies incorporate limited representation of the diverse sea-ice connected communities, according to direct springtime observations in the Belcher Islands Archipelago, Hudson Bay, Canada.Despite their wide use in past sea-ice reconstructions, the seasonal, habitat and species-based sources of sedimentary sea-ice proxies are poorly understood. Here, we conduct direct observations of the community composition of diatoms, dinoflagellate cysts and highly branched isoprenoid lipids within the sea ice, water column, sediment traps and sediment surface in the Belcher Islands Archipelago, Hudson Bay throughout spring 2019. We find that Arctic diatom and dinoflagellate cysts species commonly used as sea-ice proxies appear to be only indirectly linked to sea-ice conditions, and that the sediment assemblages of these groups overrepresent summertime pelagic blooms. Species contributing to the diverse sea-ice diatom communities are rare in the sediment. Dinoflagellate cysts form a typical Arctic assemblage in the sediment, although they are virtually absent in the sea ice and water column in spring. We also find that certain highly branched isoprenoid lipids that were previously considered indicators of open water, can be produced in sea-ice. We conclude that contextual knowledge and a multiproxy approach are necessary in reconstruction, encouraging further studies on the sources and controls of sea-ice proxy production in different geographic areas.
Published: 2023

4. Cost of observability inequalities for elliptic equations in 2-d with potentials and applications to control theory

Author: Ervedoza, Sylvain, Le Balc’h, Kévin, Institut de Mathématiques de Bordeaux (IMB), Université Bordeaux Segalen - Bordeaux 2-Université Sciences et Technologies - Bordeaux 1 (UB)-Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux (Bordeaux INP)-Centre National de la Recherche Scientifique (CNRS), Control And GEometry (CaGE ), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and ANR-20-CE40-0009,TRECOS,Nouvelles directions en contrôle et stabilisation: Contraintes et termes non-locaux(2020)
Subjects: Quantitative unique continuation, Applied Mathematics, Control, [MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP], [MATH.MATH-OC]Mathematics [math]/Optimization and Control [math.OC], Elliptic equations, Analysis
Abstract: The goal of this article is to obtain observability estimates for non-homogeneous elliptic equations in the presence of a potential, posed on a smooth bounded domain Ω in 2-d and observed from a non-empty open subset ω ⊂ Ω. More precisely, for every real-valued bounded potential V, our main result shows that, when Ω has a finite number of holes, the observability constant of the elliptic operator −∆ + V, with domain H^2 ∩ H^1_0(Ω), is of the form C exp (C |V|^{1/2} \log^{1/2}(|V|)) where C is a positive constant depending only on Ω and ω. Our methodology of proof is crucially based on the one recently developed by Logunov, Malinnikova, Nadirashvili, and Nazarov, in the context of the Landis conjecture on exponential decay of solutions to homogeneous elliptic equations in the plane. The main difference and additional difficulty is that the zero set of the solutions to elliptic equations with source term can be very intricate and should be dealt with carefully. As a consequence of these new observability estimates, we obtain new results concerning control of semi-linear elliptic equations in the spirit of Fernández-Cara, Zuazua's open problem concerning small-time global null-controllability of slightly super-linear heat equations.
Published: 2023

5. 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

6. Index theorems for graph-parametrized optimal control problems

Author: Andrei Agrachev, Stefano Baranzini, Ivan Beschastnyi, Scuola Internazionale Superiore di Studi Avanzati / International School for Advanced Studies (SISSA / ISAS), Control And GEometry (CaGE ), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Universidade de Aveiro, and The work of the third author was supported through the CIDMA Center for Research and Development in Mathematics and Applications, and the Portuguese Foundation for Science and Technology ('FCT - Fundacao para a Ciencia e a Tecnologia') within the project UIDP/04106/2020.
Subjects: Mathematics - Differential Geometry, Differential Geometry (math.DG), Optimization and Control (math.OC), Applied Mathematics, FOS: Mathematics, General Physics and Astronomy, Statistical and Nonlinear Physics, [MATH.MATH-OC]Mathematics [math]/Optimization and Control [math.OC], Mathematics - Optimization and Control, Mathematical Physics
Abstract: In this paper we prove Morse index theorems for a big class of constrained variational problems on graphs. Such theorems are useful in various physical and geometric applications. Our formulas compute the difference of Morse indices of two Hessians related to two different graphs or two different sets of boundary conditions. Several applications such as the iteration formulas or lower bounds for the index are proved., 30 pages, 4 figures
Published: 2023

7. Analysis of the Rolling Carpet Strategy to Eradicate an Invasive Species

Author: Luis Almeida, Alexis Léculier, Nicolas Vauchelet, Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Modelling and Analysis for Medical and Biological Applications (MAMBA), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire Analyse, Géométrie et Applications (LAGA), Université Paris 8 Vincennes-Saint-Denis (UP8)-Centre National de la Recherche Scientifique (CNRS)-Université Sorbonne Paris Nord, European Project: 740623,H2020 Pilier ERC,ADORA(2017), and Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
Subjects: Comparison principle, Population dynamics, comparison principle AMS subject classifications: 35K57, Applied Mathematics, Reaction-diusion equations, 35C07, 92D25, Computational Mathematics, Mathematics - Analysis of PDEs, Reaction-diffusion equations, FOS: Mathematics, [MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP], comparison principle AMS subject classications: 35K57, AMS subject classifications: 35K57, 92D25, 35C07, Analysis, Analysis of PDEs (math.AP)
Abstract: International audience; In order to prevent the propagation of human diseases transmitted by mosquitoes (such as dengue or zika), one possible solution is to act directly on the mosquito population. In this work, we consider an invasive species (the mosquitoes) and we study two strategies to eradicate the population in the whole space by a local intervention. The dynamics of the population is modeled through a bistable reaction diffusion equation in an one dimensional setting and both strategies are based on the same idea : we act on a moving interval. The action of the first strategy is to kill as many individuals as we can in this moving interval. The action of the second strategy is to release sterile males in this moving interval. For both strategies, we manage to generate traveling waves that propagate in the opposite direction relative to the one of the natural invasive traveling wave. These cases correspond to succeeding in eradicating the invasive species. Furthermore, for the first strategy, we fully characterize the minimal size of the interval. All the results are illustrated by numerical simulations.
Published: 2023

8. Degenerate Cahn-Hilliard equation: From nonlocal to local

Author: Charles Elbar, Jakub Skrzeczkowski, Sorbonne Université (SU), Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Modelling and Analysis for Medical and Biological Applications (MAMBA), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institute of Mathematics [Warsaw], Faculty of Mathematics, Informatics, and Mechanics [Warsaw] (MIMUW), and University of Warsaw (UW)-University of Warsaw (UW)
Subjects: Mathematics - Analysis of PDEs, Nonlocal Cahn-Hilliard equation, Applied Mathematics, FOS: Mathematics, Aggregation-Diﬀusion, [MATH]Mathematics [math], 35B40, 35D30, 35K25, 35K55, Singular limit, 2020 Mathematics Subject Classiﬁcation. 35B40, 35D30, 35K25, 35K55, Analysis, Analysis of PDEs (math.AP), Degenerate Cahn-Hilliard equation
Abstract: International audience; There has been recently an important interest in deriving rigorously the Cahn-Hilliard equation from the nonlocal equation, also called aggregation equation. So far, only non-degenerate mobilities were treated. Since we are motivated by models for the biomechanics of living tissues, it is useful to include degenerate motilities. In this framework, we present a new method to show the convergence of the nonlocal to the local degenerate Cahn-Hilliard equation. The method includes the use of nonlocal Poincar\'e and compactness inequalities.
Published: 2023

9. Mapping the Energy Landscape from a Nanocrystal-Based Field Effect Transistor under Operation Using Nanobeam Photoemission Spectroscopy

Author: Mariarosa Cavallo, Erwan Bossavit, Huichen Zhang, Corentin Dabard, Tung Huu Dang, Adrien Khalili, Claire Abadie, Rodolphe Alchaar, Dario Mastrippolito, Yoann Prado, Loïc Becerra, Michael Rosticher, Mathieu G. Silly, James K. Utterback, Sandrine Ithurria, José Avila, Debora Pierucci, Emmanuel Lhuillier, Physico-chimie et dynamique des surfaces (INSP-E6), Institut des Nanosciences de Paris (INSP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et d'Etude des Matériaux (UMR 8213) (LPEM), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), QUAD : Physique Quantique et Dispositifs, 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)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Département de Physique de l'ENS-PSL, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Dipartimento di Fisica [L'Aquila], Università degli Studi dell'Aquila = University of L'Aquila (UNIVAQ), Nanostructures et optique (INSP-E4), Acoustique pour les nanosciences (INSP-E3), ANR-19-CE24-0022,COPIN,Détecteur plasmonique à nanoCristaux colloïdaux: une nouvelle filière pour l'OPtoélectronique INfrarouge(2019), ANR-19-CE09-0017,FRONTAL,Nanocristaux Colloïdaux Dopés Infrarouges(2019), ANR-19-CE09-0026,GRaSkop,Tuning Giant Rashba Spin-Orbit Coupling in Polar Single Layer Transition Metal Dichalcogenides(2019), ANR-21-CE24-0012,BRIGHT,Diode électroluminescente infrarouge brillante par exaltation du couplage lumière-matière(2021), ANR-21-CE09-0029,MixDFerro,Heterostructures à dimensions mixtes sous contrôle ferroélectrique 2D(2021), ANR-22-CE09-0018,QuickTera,Nanocristaux de HgTe une nouvelle plateforme pour l'optoélectronique THz(2022), ANR-18-CE30-0023,IPER-Nano2,Nanocristaux de perovskite inorganique pour la nanophotonique(2018), and European Project: 756225,blackQD
Subjects: nanocrystals, energy landscape, Mechanical Engineering, field-effect transistor, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], General Materials Science, Bioengineering, General Chemistry, X-ray photoemission, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, Condensed Matter Physics
Abstract: International audience; As the field of nanocrystal-based optoelectronics matures, more advanced techniques must be developed in order to reveal the electronic structure of nanocrystals, particularly with devicerelevant conditions. So far, most of the efforts have been focused on optical spectroscopy, and electrochemistry where an absolute energy reference is required. Device optimization requires probing not only the pristine material but also the material in its actual environment (i.e., surrounded by a transport layer and an electrode, in the presence of an applied electric field). Here, we explored the use of photoemission microscopy as a strategy for operando investigation of NC-based devices. We demonstrate that the method can be applied to a variety of materials and device geometries. Finally, we show that it provides a direct access to the metal-semiconductor interface band bending as well as the distance over which the gate effect propagates in field-effect transistors.
Published: 2023

10. Spin-down by dynamo action in simulated radiative stellar layers

Author: Ludovic Petitdemange, Florence Marcotte, Christophe Gissinger, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Control, Analysis and Simulations for TOkamak Research (CASTOR), Inria Sophia Antipolis - Méditerranée (CRISAM), Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jean Alexandre Dieudonné (LJAD), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), Laboratoire Jean Alexandre Dieudonné (LJAD), Physique Non-Linéaire, 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, 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)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Département de Physique de l'ENS-PSL, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), ANR-19-ERC7-0008,DYNSEED,Graines minimales de dynamos célestes(2019), and ANR-19-CE30-0025,MagnetDrive,Transformations d'energies controlées par instabilités magnetohydrodynamiques - de l'astrophysique aux applications industrielles(2019)
Subjects: [PHYS.PHYS.PHYS-FLU-DYN]Physics [physics]/Physics [physics]/Fluid Dynamics [physics.flu-dyn], Multidisciplinary, Astrophysics - Solar and Stellar Astrophysics, FOS: Physical sciences, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Solar and Stellar Astrophysics (astro-ph.SR)
Abstract: International audience; The evolution of a star is influenced by its internal rotation dynamics through transport and mixing mechanisms, which are poorly understood. Magnetic fields can play a role in transporting angular momentum and chemical elements, but the origin of magnetism in radiative stellar layers is unclear. Using global numerical simulations, we identify a subcritical transition from laminar flow to turbulence caused by the generation of a magnetic dynamo. Our results have many properties of the theoretically proposed Tayler-Spruit dynamo mechanism, which strongly enhances transport of angular momentum in radiative zones. The dynamo generates deep toroidal fields that are screened by the stellar outer layers. This mechanism could produce strong magnetic fields inside radiative stars without an observable field on their surface.
Published: 2023

11. Steering self-organisation through confinement

Author: Araújo, Nuno A.M., Janssen, Liesbeth M.C., Barois, Thomas, Boffetta, Guido, Cohen, Itai, Corbetta, Alessandro, Dauchot, Olivier, Dijkstra, Marjolein, Durham, William M., Dussutour, Audrey, Garnier, Simon, Gelderblom, Hanneke, Golestanian, Ramin, Isa, Lucio, Koenderink, Gijsje H., Löwen, Hartmut, Metzler, Ralf, Polin, Marco, Royall, C. Patrick, Šarić, Anđela, Sengupta, Anupam, Sykes, Cécile, Trianni, Vito, Tuval, Idan, Vogel, Nicolas, Yeomans, Julia M., Zuriguel, Iker, Marin, Alvaro, Volpe, Giorgio, Sub Soft Condensed Matter, Soft Condensed Matter and Biophysics, Sub Soft Condensed Matter, Soft Condensed Matter and Biophysics, MESA+ Institute, Physics of Fluids, Universidade de Lisboa, Eindhoven University of Technology [Eindhoven] (TU/e), Laboratoire Ondes et Matière d'Aquitaine (LOMA), Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Torino = University of Turin (UNITO), Cornell University [New York], Laboratory of Atomic and Solid State Physics [Ithaca] (LASSP), Gulliver (UMR 7083), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Utrecht University [Utrecht], University of Sheffield [Sheffield], Centre de Recherches sur la Cognition Animale - UMR5169 (CRCA), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre de Biologie Intégrative (CBI), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Toulouse Mind & Brain Institut (TMBI), Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT), New Jersey Institute of Technology [Newark] (NJIT), Max Planck Institute for Dynamics and Self-Organization (MPIDS), Max-Planck-Gesellschaft, Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Department of Materials [ETH Zürich] (D-MATL), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Kavli Institute of Nanosciences [Delft] (KI-NANO), Delft University of Technology (TU Delft), Heinrich Heine Universität Düsseldorf = Heinrich Heine University [Düsseldorf], University of Potsdam = Universität Potsdam, Institut Mediterrani d'Estudis Avancats (IMEDEA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Universidad de las Islas Baleares (UIB), Institute of Science and Technology [Klosterneuburg, Austria] (IST Austria), University of Luxembourg [Luxembourg], Matière Cellulaire Active, 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)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Département de Physique de l'ENS-PSL, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institute of Cognitive Sciences and Technologies, National Research Council of Italy (CNR) (ISTC), Universidad de Navarra [Pamplona] (UNAV), University of Twente, Department of Chemistry [University College of London], University College of London [London] (UCL), ANR-18-CE33-0006,MSR,Machines Morpho-fonctionelles en Essaim(2018), ANR-14-CE09-0006,Actin2Nucleus,Connexion mécanique entre le cytosquelette d'actine et le noyau(2014), ANR-12-BSV5-0014,Contract,Nouveaux systèmes biomimétiques pour étudier la contractilité acto-myosine cellulaire(2012), European Project: 884902,SoftML, European Project: 802960,NEPA, European Project: 955910,PHYMOT, and European Project: 678573,H2020,ERC-2015-STG,NanoPacks(2016)
Subjects: Pattern-formation, Physics - Physics and Society, Chemistry(all), [SDV]Life Sciences [q-bio], [PHYS.PHYS.PHYS-BIO-PH]Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], Collective behavior, FOS: Physical sciences, Physics and Society (physics.soc-ph), General Chemistry, Condensed Matter - Soft Condensed Matter, Condensed Matter Physics, Nonlinear Sciences - Adaptation and Self-Organizing Systems, Particles, Biological Physics (physics.bio-ph), Information, Soft Condensed Matter (cond-mat.soft), Physics - Biological Physics, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], Adaptation and Self-Organizing Systems (nlin.AO)
Abstract: Self-organisation is the spontaneous emergence of spatio-temporal structures and patterns from the interaction of smaller individual units. Examples are found across many scales in very different systems and scientific disciplines, from physics, materials science and robotics to biology, geophysics andastronomy. Recent research has highlighted how self-organisation can be both mediated and controlled by confinement. Confinement is an action over a system that limits its units’ translational and rotational degrees of freedom, thus also influencing the system’s phase space probability density; it can functionas either a catalyst or inhibitor of self-organisation. Confinement can then become a means to actively steer the emergence or suppression of collective phenomena in space and time. Here, to provide a common framework and perspective for future research, we examine the role of confinement in the self-organisation of soft-matter systems and identify overarching scientific challenges that need to be addressed to harness its full scientific and technological potential in soft matter and related fields.By drawing analogies with other disciplines, this framework will accelerate a common deeper understanding of self-organisation and trigger the development of innovative strategies to steer it using confinement, with impact on, e.g., the design of smarter materials, tissue engineering for biomedicineand in guiding active matter.
Published: 2023

12. The Essential Role of Westerly Wind Bursts in ENSO Dynamics and Extreme Events Quantified in Model 'Wind Stress Shaving' Experiments

Author: Sungduk Yu, Alexey V. Fedorov, Department of Earth and Planetary Sciences [Kobe], Kobe University, Océan et variabilité du climat (VARCLIM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and ANR-18-MPGA-0001,ARCHANGE,Changement climatique et Arctique et circulation océanique globale(2018)
Subjects: Atmospheric Science, [SDU]Sciences of the Universe [physics]
Abstract: Westerly wind bursts (WWBs)—brief but strong westerly wind anomalies in the equatorial Pacific—are believed to play an important role in El Niño–Southern Oscillation (ENSO) dynamics, but quantifying their effects is challenging. Here, we investigate the cumulative effects of WWBs on ENSO characteristics, including the occurrence of extreme El Niño events, via modified coupled model experiments within Community Earth System Model (CESM1) in which we progressively reduce the impacts of wind stress anomalies associated with model-generated WWBs. In these “wind stress shaving” experiments we limit momentum transfer from the atmosphere to the ocean above a preset threshold, thus “shaving off” wind bursts. To reduce the tropical Pacific mean state drift, both westerly and easterly wind bursts are removed, although the changes are dominated by WWB reduction. As we impose progressively stronger thresholds, both ENSO amplitude and the frequency of extreme El Niño decrease, and ENSO becomes less asymmetric. The warming center of El Niño shifts westward, indicating less frequent and weaker eastern Pacific (EP) El Niño events. Removing most wind burst–related wind stress anomalies reduces ENSO mean amplitude by 22%. The essential role of WWBs in the development of extreme El Niño events is highlighted by the suppressed eastward migration of the western Pacific warm pool and hence a weaker Bjerknes feedback under wind shaving. Overall, our results reaffirm the importance of WWBs in shaping the characteristics of ENSO and its extreme events and imply that WWB changes with global warming could influence future ENSO.
Published: 2022

13. Cropping leads to loss of soil organic matter: How can we prevent it?

Author: Chaplot, Vincent, Smith, Pete, 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), INSTITUTE OF BIOLOGICAL AND ENVIRONMENTAL SCIENCES, and University of Aberdeen
Subjects: [SDE]Environmental Sciences, Soil Science
Abstract: International audience
Published: 2023

14. Consensus formation in first-order graphon models with time-varying topologies

Author: Bonnet, Benoît, Duteil, Nastassia Pouradier, Sigalotti, Mario, Control And GEometry (CaGE ), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Modelling and Analysis for Medical and Biological Applications (MAMBA), Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: Consensus Formation, Algebraic Connectivity, MSC2020 Subject Classification : 05C63, 05C90, 37L15, 93A16, Applied Mathematics, Multi-Agent Systems, Functional Analysis (math.FA), Mathematics - Functional Analysis, Optimization and Control (math.OC), Modeling and Simulation, FOS: Mathematics, 05C63, 05C90, 37L15, 93A16, [MATH.MATH-OC]Mathematics [math]/Optimization and Control [math.OC], [MATH]Mathematics [math], Mathematics - Optimization and Control, Scrambling Coefficient, Graphon Dynamics, Persistence Conditions
Abstract: In this article, we investigate the asymptotic formation of consensus for several classes of time-dependent cooperative graphon dynamics. After motivating the use of this type of macroscopic models to describe multi-agent systems, we adapt the classical notion of scrambling coefficient to this setting, leverage it to establish sufficient conditions ensuring the exponential convergence to consensus with respect to the $L^{\infty}$-norm topology. We then shift our attention to consensus formation expressed in terms of the $L^2$-norm, and prove three different consensus result for symmetric, balanced and strongly connected topologies, which involve a suitable generalisation of the notion of algebraic connectivity to this infinite-dimensional framework. We then show that, just as in the finite-dimensional setting, the notion of algebraic connectivity that we propose encodes information about the connectivity properties of the underlying interaction topology. We finally use the corresponding results to shed some light on the relation between $L^2$- and $L^{\infty}$-consensus formation, and illustrate our contributions by a series of numerical simulations., Comment: 48 pages, 16 figures
Published: 2022

15. Recent Advances in Adaptive Coarse Spaces and Availability in Open Source Libraries

Author: Dolean, Victorita, Hecht, Frédéric, Jolivet, Pierre, Nataf, Frédéric, Tournier, Pierre-Henri, Laboratoire Jean Alexandre Dieudonné (LJAD), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Algorithms and parallel tools for integrated numerical simulations (ALPINES), Institut National des Sciences Mathématiques et de leurs Interactions (INSMI)-Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Algorithmes Parallèles et Optimisation (IRIT-APO), Institut de recherche en informatique de Toulouse (IRIT), Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT)-Université de Toulouse (UT)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Toulouse Mind & Brain Institut (TMBI), Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT), and Centre National de la Recherche Scientifique (CNRS)
Subjects: Journal, Applied mathematics, Example, [MATH.MATH-NA]Mathematics [math]/Numerical Analysis [math.NA]
Abstract: International audience; Scalability of parallel solvers for problems with high heterogeneities relies on adaptive coarse spaces built from generalized eigenvalue problems in the subdomains. The corresponding theory is powerful and flexible but the development of an efficient parallel implementation is challenging. We report here on recent advances in adaptive coarse spaces and on their open source implementations.
Published: 2022

16. Western and Central Tropical Pacific Rainfall Response to Climate Change: Sensitivity to Projected Sea Surface Temperature Patterns

Author: Dutheil, Cyril, Lengaigne, Matthieu, Vialard, Jérôme, Jullien, Swen, Menkès, Christophe E., Leibniz Institute for Baltic Sea Research Warnemünde (IOW), MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Océan et variabilité du climat (VARCLIM), 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), 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), Ecologie marine tropicale des océans Pacifique et Indien (ENTROPIE [Nouvelle-Calédonie]), Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Ifremer - Nouvelle-Calédonie, and Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de la Nouvelle-Calédonie (UNC)
Subjects: Atmospheric Science, [SDU]Sciences of the Universe [physics], [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Sea surface temperature, Hydrologic cycle, Regional models, Climate change, Precipitation, Climate models
Abstract: Rainfall projections from the Coupled Model Intercomparison Project (CMIP) models are strongly tied to projected sea surface temperature (SST) spatial patterns through the “warmer-gets-wetter” mechanism. While these models consistently project an enhanced equatorial warming, they, however, indicate much more uncertain changes in zonal SST gradients. That translates into large uncertainties on rainfall projections. Here, we force an atmospheric model with synthetic SSTs whose zonal SST gradient changes span the range of CMIP5 uncertainties in the presence and in the absence of the robust equatorially enhanced warming. Our results confirm that projected rainfall changes are dominated by the effect of circulation changes, which are tied to SST through the “warmer-gets-wetter” mechanism. We show that SPCZ rainfall changes are entirely driven by the uncertain zonal SST gradient changes. The western equatorial Pacific rainfall increase is largely controlled by the robust enhanced equatorial warming for modest zonal SST gradient changes. However, for larger values, the effect of the zonal SST gradient change on rainfall projections becomes dominant due to nonlinear interactions with the enhanced equatorial warming. Overall, our study demonstrates that uncertainties in the zonal SST gradient changes strongly contribute to uncertainties in rainfall projections over both the South Pacific convergence zone and western equatorial Pacific. It is thus critical to reduce these uncertainties to produce more robust precipitation estimates.
Published: 2022

17. Modelling the effect of the tidal cycle on the high phytoplankton biomass area of Cape Trafalgar (SW Iberian Peninsula)

Author: Sala, Iria, Vallina, Sergio, Lévy, Marina, Bolado-Penagos, Marina, García, Carlos, Echevarría, Fidel, Sánchez-Garrido, José, Instituto Universitario de Investigación Marina (INMAR), Universidad de Cádiz (UCA), University of Strathclyde [Glasgow], Instituto Espagňol de Oceanografia (IEO), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), 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), and Universidad de Málaga [Málaga] = University of Málaga [Málaga]
Subjects: Strait of Gibraltar, physical-biological coupled model, Cape Trafalgar, tidal mixing, phytoplankton, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography
Abstract: International audience; Physical-biological interactions in the ocean are known to be crucial for understanding ecosystem processes. This is particularly relevant in the highly dynamic coastal regions, where the biogeochemical processes associated with higher-frequency perturbations such as tidal waves play a key role in primary production. In this study, we examine the influence of the tide-topography interaction on the high productivity area of Cape Trafalgar (NW limit of the Strait of Gibraltar, Iberian Peninsula) using a high-resolution ocean circulation model coupled to an ecosystem model. The obtained results highlight the relevance of the tidal cycle explaining the high phytoplankton biomass that characterises this region through an active and periodic forcing, resulting in a pulsating upwelling system. Our model shows that the interaction of the westward zonal component of the tidal current (uvel) with the submarine ridge (i.e., Barbate High) that characterises this region, which is perpendicular to the coast, results in the pumping of deep, cold, salty, and nutrient-rich waters to the well-illuminated subsurface waters, fuelling phytoplankton growth. At the same time, the interaction of the westward tidal current with the ridge leads to the development of a cyclonic eddy, which enables the redistribution of the upwelled waters over and to the east of Barbate High. The fortnightly tidal period has been identified as the most influential because (an effective) tidal-pumping process only takes place when the westward uvel is ∼ 0.42 m s−1, a condition attained between ∼ 3 days before and after the moment of maximum tidal flow during spring tides. Simultaneously, the energy and the associated horizontal and vertical mixing of the cyclonic gyre also vary with the tidal cycle, being stronger during spring tides. Both tidally driven processes, i.e., the cyclical upslope advection of deep nutrient-rich water and the influence of the cyclonic gyre, are the main mechanisms that lead to the development of a persistent phytoplankton-rich tongue over Barbate High. Consequently, Cape Trafalgar acts as a source of nutrient-and phytoplankton-rich waters to the surrounding waters.
Published: 2023

18. On the problem of minimizing the epidemic final size for SIR model by social distancing

Author: Bliman, Pierre-Alexandre, Rapaport, Alain, Sorbonne Université (SU), Université Paris Cité (UPCité), Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Modelling and Analysis for Medical and Biological Applications (MAMBA), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Mathématiques, Informatique et STatistique pour l'Environnement et l'Agronomie (MISTEA), 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), and IFAC - International Federation of Automatic Control
Subjects: optimal control, Epidemiological models optimal control L1 controls infinite horizon, L1 controls, [SDV.SPEE]Life Sciences [q-bio]/Santé publique et épidémiologie, Epidemiological models, infinite horizon, [SPI.AUTO]Engineering Sciences [physics]/Automatic
Abstract: Droits auteurs: https://www.ifac2023.org/archives/001/202211/IFAC2023_2ndCFP_20221115.pdf; International audience; We revisit the problem of minimizing the epidemic final size in the SIR model through social distancing. In the existing literature, this problem has been considered by imposing a priori interval structure on the time period during which interventions are enforced. We show that when considering the more general class of controls with an L1 constraint on the confinement effort to reduce the infection rate, the support of the optimal control is still a single time interval. In other words, for the problem of minimizing the epidemic final size in the SIR model through social distancing, there is no benefit in splitting interventions on several disjoint time periods. The techniques we deploy here are different than what has been proposed in the literature, and could be potentially applied to other problems.
Published: 2023

19. Control theory perspectives on mathematical epidemiology

Author: Bliman, Pierre-Alexandre, Rapaport, Alain, Modelling and Analysis for Medical and Biological Applications (MAMBA), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Mathématiques, Informatique et STatistique pour l'Environnement et l'Agronomie (MISTEA), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut Agro Montpellier, and 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)
Subjects: Mathematical epidemiology, [MATH]Mathematics [math]
Abstract: Invited session; International audience; Mathematical epidemiology may benefit from techniques and concepts from Control theory. As a matter of fact, understanding and controlling the spread of an infectious epidemic necessitates modeling of the phenomena underlying the propagation, estimation of the characteristic parameters and of the state of the epidemic, scheduling and scaling of the control measures. These are generic questions, for which tools have been developed in Control, admittedly in quite different applicative contexts. The aim of this session is precisely to explore in more details potential profit, as well as limitations, of this cross-fertilization. Several common features of the problems arising from the application of Control theory to the handling of epidemics are worth mentioning here. First, the transmission of infection is inherently a nonlinear phenomenon. Second, the usual measurements of prevalence leads to a lack of observability and identifiability of the studied state space models at equilibria, a point which complicates the handling of these issues when the state is closed from these singular points (beginning of outbreak or final stabilization). Last, the cost functions of interest are usually non-conventional, typically proportional to the effort made (and not quadratic), and state constraint are not uncommon. All this, plus the important uncertainty present on the models and on the data, makes the corresponding problems rather sensitive. The six contributions that constitute this session offer a partial vision of issues to be adressed. They are more especially related to observability and identifiability (papers 1 and 2), and to optimal control applied to epidemic processes (papers 2 to 6).
Published: 2023

20. Unified non-equilibrium simulation methodology for flow through nanoporous carbon membrane

Author: Monet, Geoffrey, Bocquet, Marie-Laure, Bocquet, Lydéric, Micromegas : Nano-Fluidique, 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)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Département de Physique de l'ENS-PSL, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), and European Project: 899528 ,ITS-THIN
Subjects: Nanotubes, Condensed Matter - Mesoscale and Nanoscale Physics, Energy harvesting, Desalination, Classical molecular dynamic simulations, FOS: Physical sciences, Condensed Matter - Soft Condensed Matter, 2D materials, [PHYS.PHYS.PHYS-COMP-PH]Physics [physics]/Physics [physics]/Computational Physics [physics.comp-ph], Chemical elements, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Soft Condensed Matter (cond-mat.soft), Electrokinetic phenomena, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Graphene, Electroosmosis, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Nanomaterials
Abstract: The emergence of new nanoporous materials, based e.g. on 2D materials, offers new avenues for water filtration and energy. There is accordingly a need to investigate the molecular mechanisms at the root of the advanced performances of these systems in terms of nanofluidic and ionic transport. In this work, we introduce a novel unified methodology for Non-Equilibrium classical Molecular Dynamic simulations (NEMD), allowing to apply likewise pressure, chemical potential and voltage drops across nanoporous membranes and quantifying the resulting observables characterizing confined liquid transport under such external stimuli. We apply the NEMD methodology to study a new type of synthetic Carbon NanoMembranes (CNM), which have recently shown outstanding performances for desalination, keeping high water permeability while maintaining full salt rejection. The high water permeance of CNM, as measured experimentally, is shown to originate in prominent entrance effects associated with negligible friction inside the nanopore. Beyond, our methodology allows to fully calculate the symmetric transport matrix and the cross-phenomena such as electro-osmosis, diffusio-osmosis, streaming currents, etc. In particular, we predict a large diffusio-osmotic current across the CNM pore under concentration gradient, despite the absence of surface charges. This suggests that CNMs are outstanding candidates as alternative, scalable membranes for osmotic energy harvesting., Comment: 13 pages, 16 figures, submitted to J. Chem Phys
Published: 2023

21. Hydroclimate reconstruction during the last 1000 years inferred from the mineralogical and geochemical composition of a sediment core from Lake-Azuei (Haiti)

Author: David Noncent, Abdelfettah Sifeddine, Evens Emmanuel, Marie-Helene Cormier, Francisco J Briceño-Zuluaga, Mercedes Mendez-Millan, Bruno Turcq, Sandrine Caquineau, Jorge Valdés, Juan Pablo Bernal, John W King, Irina Djouraev, Fethiye Cetin, Heather Sloan, Université Quisqueya, Faculté des Sciences, de Génie et d'Architecture (FSGA), LMI CARIBACT, URGéo, Université d’Etat d’Haïti, Faculté des Sciences (UEH, FDS), Variabilité à long terme du climat de l'océan (VALCO), 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), University of Rhode Island (URI), New Granada Military University (UMNG), Laboratorio de Sedimentologıa y Paleoambientes (LASPAL), Universidad Nacional Autónoma de México = National Autonomous University of Mexico (UNAM), Lehman College [CUNY], and City University of New York [New York] (CUNY)
Subjects: Archeology, Global and Planetary Change, Ecology, [SDU]Sciences of the Universe [physics], Paleontology, Earth-Surface Processes
Abstract: International audience; This study aims to reconstruct the hydro-climatic variations over the last 1000 years in Haiti using mineralogical and geochemical composition of well dated lacustrine sediment core retrieved from Lake Azuei. The results show changes in sedimentological processes linked to environmental and climatic variations. The general pattern suggests a wetter Medieval Climate Anomaly (MCA), drier Little Ice Age (LIA), high climate variability during the MCA-LIA transition and more anthropogenic impacts that dominate natural climate during the Current Warm Period (CWP). The MCA period (~1000–1100 CE) thus appears marked by increase sedimentation rate supported by higher terrigenous input linked to erosive events particularly increases in precipitation. During the LIA, particularly from ~1450 to 1600 CE, there is a great variation toward a decrease of terrigenous input, which is related to a decrease on sedimentation rate and increase Mg-calcite precipitation, suggesting less precipitation and high evaporation respectively during dry climate conditions. The MCA-LIA transition (~1200–1400 CE) is characterized by variations between terrigenous input, Mg-calcite formation and organic matter deposition, which indicate succession of dry and humid conditions. The CWP (1800–2000 CE) shows a progressive increase on sedimentation rate and decrease of gray level, which indicate more organic matter sedimentation as consequence of anthropogenic activities in the surrounding basin of the lake. High-resolution gray level analysis, which reflects principally variations in terrigenous input, carbonate mineral formation and organic matter deposition, shows that the AMO, NAO, PDO and ENSO are the principal modes affecting the hydro-climatic changes in Haiti during the last millennium. In addition, temporal correlation of other Caribbean paleoclimate records with our geochemical and mineralogical data, suggests that trends observed in Lake Azuei were controlled by regional climate, likely associated with shifts in the position of the ITCZ.
Published: 2023

22. Global stabilization of sterile insect technique model by feedback laws

Author: Bidi, Kala Agbo, Almeida, Luis, Coron, Jean-Michel, Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Control And GEometry (CaGE ), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), and Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: [SDV.EE.SANT]Life Sciences [q-bio]/Ecology, environment/Health, Sterile Insect Technique, Mosquito population control, Dynamical control system, Pest control, Optimization and Control (math.OC), FOS: Mathematics, Lyapunov global stabilization, Vector borne disease, [MATH.MATH-OC]Mathematics [math]/Optimization and Control [math.OC], 93D15, 93D20, 92D25, Feedback design, Mathematics - Optimization and Control, Backstepping feedback
Abstract: The Sterile Insect Technique or SIT is presently one of the most ecological methods for controlling insect pests responsible for disease transmission or crop destruction worldwide. This technique consists of releasing sterile males into the insect pest population. This approach aims at reducing fertility in the population and, consequently, reduce significantly the native insect population after a few generations. In this work, we study the global stabilization of a pest population at extinction equilibrium by the SIT method. We construct explicit feedback laws that stabilize the model and do numerical simulations to show the efficiency of our feedback laws. The different feedback laws are also compared taking into account their possible implementation in field interventions.
Published: 2023

23. Influence of combined temperature and food availability on Peruvian anchovy (Engraulis ringens) early life stages in the northern Humboldt Current system: A modelling approach

Author: Jorge Flores-Valiente, Christophe Lett, François Colas, Laure Pecquerie, Arturo Aguirre-Velarde, Fanny Rioual, Jorge Tam, Arnaud Bertrand, Patricia Ayón, Saidou Sall, Nicolas Barrier, Timothée Brochier, Unité de modélisation mathématique et informatique des systèmes complexes [Bondy] (UMMISCO), Université de Yaoundé I-Institut de la francophonie pour l'informatique-Université Cheikh Anta Diop [Dakar, Sénégal] (UCAD)-Université Gaston Bergé (Saint-Louis, Sénégal)-Université Cadi Ayyad [Marrakech] (UCA)-Sorbonne Université (SU)-Institut de Recherche pour le Développement (IRD [France-Nord]), MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), 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), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD), Instituto del Mar del Peru (IMARPE), Laboratoire de Physique de l'Atmosphère et de l'Océan Siméon Fongang (LPAO-SF), École Supérieure Polytechnique de Dakar (ESP), Université Cheikh Anta Diop [Dakar, Sénégal] (UCAD)-Université Cheikh Anta Diop [Dakar, Sénégal] (UCAD), and ANR-18-CE32-0009,SOLAB,Interactions planctoniques, facteurs environnementaux et conséquences biologique/géochimiques dans le laboratoire côtier sud-Sénégalais(2018)
Subjects: Larval growth, Early life stages survival, [SDV.SA.STP]Life Sciences [q-bio]/Agricultural sciences/Sciences and technics of fishery, Geology, Peruvian anchovy, Aquatic Science, Ichthyop-DEB model, Larval drift
Abstract: International audience; In the northern Humboldt Current system (NHCS), the Peruvian anchovy (Engraulis ringens) constitutes the bulk of landings and has a significant socioeconomic contribution. Understanding the impact of environment on the early-life stages of anchovy and further population dynamics remains challenging. Climate variability at a variety of scales modulates currents velocity, temperature and food availability, impacting early-life stages drift, growth and survival. In order to investigate these impacts, we developed Ichthyop-DEB, an individual-based model including larval retention processes and a Dynamic Energy Budget (DEB) bioenergetic module for larval growth. First, we assessed the effect of hydrodynamic simulations horizontal resolution on simulated larval retention patterns using a recruitment age-criterion of 30 days. Then, we evaluated the impact of the following biological processes on simulated larval recruitment patterns: (i) a minimum size-criterion (2 cm), as opposed to a minimum age-criterion (30 days), to be considered as recruited, (ii) the upper larval thermal limit tolerance of the species, for which lab experiments are lacking, and (iii) a constant larval mortality rate. We found that using different resolutions of the hydrodynamic model (10 and 2 km) led to similar simulated larval retention patterns. Retention was highest when spawning occurred in the superficial layer (0–15 m) in austral winter and in the deepest considered layer (30–45 m) in summer. Coupling with the DEB model produced contrasted growth patterns on the continental shelf with a strong month-latitude interaction. Larval recruitment was strongest from 6° to 10° S in austral summer, largely contributing to the average seasonal pattern. Depending on the temperature correction function tested with the bioenergetic module, simulated larval recruitment could also be strong in the northernmost zone (2°–4°S), an area not known for abundant anchovy populations, which suggests a possible thermal growth limitation. Finally, sensitivity tests performed on larval growth limitation by food suggested a deficiency in food supply in the southernmost zone (18°–20°S).
Published: 2023

24. Parallel approximation of the exponential of Hermitian matrices

Author: Hecht, Frédéric, Kaber, Sidi-Mahmoud, Perrin, Lucas, Plagne, Alain, Salomon, Julien, Algorithms and parallel tools for integrated numerical simulations (ALPINES), Institut National des Sciences Mathématiques et de leurs Interactions (INSMI)-Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Numerical Analysis, Geophysics and Ecology (ANGE), Inria de Paris, Centre de Mathématiques Laurent Schwartz (CMLS), École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), and ANR-19-CE46-0013,ALLOWAPP,Algorithmes pour l'optimisation à grande échelle de problèmes de propagation d'ondes(2019)
Subjects: FOS: Computer and information sciences, Parallel computing, MATLAB, Numerical Analysis (math.NA), Matrix exponential, Truncation error, AMS subject classiﬁcations. 15A16, 65F60, 65L99, 65Y05, Partial fraction decomposition, Computer Science - Distributed, Parallel, and Cluster Computing, Octave, FOS: Mathematics, Taylor series, expm, Pad\'e approximation, Distributed, Parallel, and Cluster Computing (cs.DC), Mathematics - Numerical Analysis, [INFO.INFO-DC]Computer Science [cs]/Distributed, Parallel, and Cluster Computing [cs.DC], Roundoff error, [MATH.MATH-NA]Mathematics [math]/Numerical Analysis [math.NA]
Abstract: In this work, we consider a rational approximation of the exponential function to design an algorithm for computing matrix exponential in the Hermitian case. Using partial fraction decomposition, we obtain a parallelizable method, where the computation reduces to independent resolutions of linear systems. We analyze the effects of rounding errors on the accuracy of our algorithm. We complete this work with numerical tests showing the efficiency of our method and a comparison of its performances with Krylov algorithms.
Published: 2023

25. Parallel Memory-Independent Communication Bounds for SYRK

Author: Hussam Al Daas, Grey Ballard, Laura Grigori, Suraj Kumar, Kathryn Rouse, STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC), Wake Forest University, Algorithms and parallel tools for integrated numerical simulations (ALPINES), Institut National des Sciences Mathématiques et de leurs Interactions (INSMI)-Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Optimisation des ressources : modèles, algorithmes et ordonnancement (ROMA), Laboratoire de l'Informatique du Parallélisme (LIP), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Recherche en Informatique et en Automatique (Inria)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Recherche en Informatique et en Automatique (Inria)-Centre National de la Recherche Scientifique (CNRS)-Inria Lyon, Institut National de Recherche en Informatique et en Automatique (Inria), Inmar Intelligence, and European Project: 810367,EMC2(2019)
Subjects: Symmetric matrices, [INFO]Computer Science [cs], Communication costs, Convex optimization
Abstract: International audience; In this paper, we focus on the parallel communication cost of multiplying a matrix with its transpose, known as a symmetric rank-k update (SYRK). SYRK requires half the computation of general matrix multiplication because of the symmetry of the output matrix. Recent work (Beaumont et al., SPAA '22) has demonstrated that the sequential I/O complexity of SYRK is also a constant factor smaller than that of general matrix multiplication. Inspired by this progress, we establish memory-independent parallel communication lower bounds for SYRK with smaller constants than general matrix multiplication, and we show that these constants are tight by presenting communication-optimal algorithms. The crux of the lower bound proof relies on extending a key geometric inequality to symmetric computations and analytically solving a constrained nonlinear optimization problem. The optimal algorithms use a triangular blocking scheme for parallel distribution of the symmetric output matrix and corresponding computation.
Published: 2023

26. Mathematical modelling of cancer growth and drug treatments: taking into account cell population heterogeneity and plasticity

Author: Clairambault, Jean, Modelling and Analysis for Medical and Biological Applications (MAMBA), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Silviu-Iulian Niculescu, Clairambault, Jean, Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), and Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: [SDV] Life Sciences [q-bio], MSC 35B40, 35G92, 49J20, 92C50, [SDV.CAN] Life Sciences [q-bio]/Cancer, [SDV]Life Sciences [q-bio], [SDV.BA]Life Sciences [q-bio]/Animal biology, [MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP], [MATH.MATH-OC] Mathematics [math]/Optimization and Control [math.OC], [SDV.CAN]Life Sciences [q-bio]/Cancer, [MATH] Mathematics [math], [MATH.MATH-OC]Mathematics [math]/Optimization and Control [math.OC], [MATH.MATH-AP] Mathematics [math]/Analysis of PDEs [math.AP], [MATH]Mathematics [math]
Abstract: Version v2 après acceptation du document par la conférence de la prépublication hal-03938311; International audience; Mathematical models of cancer growth and evolution of cancer cell characteristics, aka traits or phenotypes, together with optimisation and optimal control methods to contain them, in the framework of adaptive dynamics of cell populations, are presented. They take into account the heterogeneity of cancer cell populations, i.e., their biological variability, and their intrinsic plasticity, i.e., their nongenetic instability that allows them to quickly adapt to changing environments. The presented vision of the cancer disease, which is specific to multicellular organisms, relies on a relatively novel vision, consistent with a billion-year evolutionary perspective. Based on recent contributions from philosophy of cancer, these mathematical models aim at designing theoretical therapeutic strategies to simultaneously contain tumour progression and limit adverse events of drugs to healthy cell populations.
Published: 2023

27. On the Suitable choice of Metal for HgTe Nanocrystal-based Photodiode: to Amalgam or not to Amalgam

Author: Alchaar, Rodolphe, Dabard, Corentin, Mastrippolito, Dario, Bossavit, Erwan, Dang, Tung Huu, Cavallo, Mariarosa, Khalili, Adrien, Zhang, Huichen, Domenach, Lucile, Ledos, Nicolas, Prado, Yoann, Troadec, David, Dai, Ji, Tallarida, Massimo, Bisti, Federico, Cadiz, Fabian, Patriarche, Gilles, Avila, José, Lhuillier, Emmanuel, Pierucci, Debora, Physico-chimie et dynamique des surfaces (INSP-E6), Institut des Nanosciences de Paris (INSP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et d'Etude des Matériaux (UMR 8213) (LPEM), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Dipartimento di Fisica [L'Aquila], Università degli Studi dell'Aquila = University of L'Aquila (UNIVAQ), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), QUAD : Physique Quantique et Dispositifs, 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)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Département de Physique de l'ENS-PSL, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), Université catholique de Lille (UCL)-Université catholique de Lille (UCL), Centrale de Micro Nano Fabrication - IEMN (CMNF - IEMN), Université catholique de Lille (UCL)-Université catholique de Lille (UCL)-Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), ALBA Synchrotron light source [Barcelone], Laboratoire de Physique de la Matière Condensée (LPMC), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre de Nanosciences et de Nanotechnologies (C2N), Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), miti cnrs, Renatech Network, CMNF, ANR-19-CE24-0022,COPIN,Détecteur plasmonique à nanoCristaux colloïdaux: une nouvelle filière pour l'OPtoélectronique INfrarouge(2019), ANR-19-CE09-0026,GRaSkop,Tuning Giant Rashba Spin-Orbit Coupling in Polar Single Layer Transition Metal Dichalcogenides(2019), ANR-19-CE09-0017,FRONTAL,Nanocristaux Colloïdaux Dopés Infrarouges(2019), ANR-22-CE09-0018,QuickTera,Nanocristaux de HgTe une nouvelle plateforme pour l'optoélectronique THz(2022), ANR-22-CE09-0037,OperaTwist,Etude in operando de la modulation de propietes electroniques des hetero-bicouche twistées(2022), ANR-21-CE24-0012,BRIGHT,Diode électroluminescente infrarouge brillante par exaltation du couplage lumière-matière(2021), ANR-21-CE09-0029,MixDFerro,Heterostructures à dimensions mixtes sous contrôle ferroélectrique 2D(2021), European Project: 756225,blackQD, and European Project: 101086358,AQDtive
Subjects: nanocrystals, infrared, nanocrystals HgTe infrared photodiode amalgam, photodiode, [CHIM.MATE]Chemical Sciences/Material chemistry, amalgam, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, HgTe
Abstract: International audience; HgTe, thanks to its unique spectral tunability in the infrared is the only material able to cover near, short and mid wave infrared. Current best devices rely on diode electrodes made from transparent conductive oxides and gold, but so far none of these completely fit for purpose. Gold is not compatible with Si foundries and transparent conductive oxides are highly lossy in this spectral range, limiting electrode transparency. Metal based electrodes appear as good alternative candidates but require further investigations. While obvious constraints of work function get raised, chemical stability appears equally important. Here we screen the use of Au, Al, Ag, and Zn as possible metal and reveal that in the case of Ag dramatic transformations of Ag and HgTe are observed. Especially, a cation exchange procedure can occur over a solid-state film without intentional heating of the sample. This process has then been studied combining both structural and electronic probes. This work points out the importance of the careful choice of surrounding electrodes in the case of HgTe since the observed mechanism is likely not limited to Ag. On the other hand, both Au and Al appear stable toward this transformation.
Published: 2023

28. Solving parametric PDEs via parsimonious discretizations: application to Uncertainty Quantification and Data Assimilation

Author: Riffaud, Sébastien, Lombardi, Damiano, Fernández, Miguel, COmputational Mathematics for bio-MEDIcal Applications (COMMEDIA), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), and Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: Cardiovascular flow modeling, [MATH]Mathematics [math], Low-rank methods, Uncertainty quantification
Abstract: International audience; This work has been motivated by data assimilation applications in biomedical engineering. In all these applications, a set of partial noisy observations of the system state have to be exploited in order to assess, at best, a set of quantities of interest. We focus here on the applications in which the state evolution can be described by a system of parametric PDEs, and the measurements have to be used in order to estimate the parameters values. Two major difficulties need to be faced. The first one is identifiability: given the observations, can we estimate the parameters? The second one is related to the estimation itself: even when considering linear PDEs, the solution depends potentially in a highly non-linear way on the parameters. When using a variational formulation this often leads to a non-linear non-convex optimisation to be solved, involving a prohibitive computational burden.The goal of the present work is to propose a framework to perform parameter estimation, accounting automatically for identifiability (by using a Bayesian formulation), and for the uncertainties. It can be seen as a possible discretisation of a Bayesian filter. The main idea consists in trying to approximate the system solution as function of space-time and parameters variables. This is done by introducing an efficient low-rank solver.Instead of keeping the discretisation of the parameters domain fixed, we make it evolved based on the system observations. This adaptation task is performed thanks to a Metropolis Hastings algorithm, enabled by a reduced-order interpolator which we can build thanks to the parametric solution. The interplay between the reduced-order interpolator and the parametric solver is crucial to get efficiency: the reduced-order interpolator makes the adaptation fast, getting a more adapted discretisation in parameters contributes to keep the cost of the parametric solver moderate, the parametric solver makes the construction of the ROM interpolator fast. As a result, we can compute, efficiently, mean, standard deviation (other moments or information related quantities) of the posterior distribution of the parameters and the statistics of the system solution. Several test-cases are presented.
Published: 2023

29. On the limit problem arising in the kinetic derivation of the Cahn-Hilliard equation

Author: Elbar, Charles, Perthame, Benoît, Skrzeczkowski, Jakub, Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Modelling and Analysis for Medical and Biological Applications (MAMBA), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institute of Mathematics [Warsaw], Faculty of Mathematics, Informatics, and Mechanics [Warsaw] (MIMUW), and University of Warsaw (UW)-University of Warsaw (UW)
Subjects: Mathematics - Analysis of PDEs, [MATH.MATH-MP]Mathematics [math]/Mathematical Physics [math-ph], 2020 MSC: 35B40, 35D30, 35K25, 35K55, FOS: Mathematics, [MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP], 35B40, 35D30, 35K25, 35K55, Analysis of PDEs (math.AP)
Abstract: The non-local degenerate Cahn-Hilliard equation is derived from the Vlasov equation with long-range attraction. We study the local limit as the delocalization parameter converges to 0. The difficulty arises from the degeneracy which requires compactness estimates, but all necessary a priori estimates can be obtained only on the nonlocal quantities yielding almost no information on the limiting solution itself. We introduce a novel condition on the nonlocal kernel which allows us to exploit the available nonlocal a priori estimates. The condition, satisfied by most of the kernels appearing in the applications, can be of independent interest. Our approach is flexible and systems can be treated as well., 15 pages + Appendix
Published: 2023

30. Recent Convection Decline in the Greenland Sea: Insights From the Mercator Ocean System Over 2008–2020

Author: Louise Abot, Christine Provost, Léa Poli, 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), and H2020 Arctic Passion project, Grant 101003472.
Subjects: Geophysics, Space and Planetary Science, Geochemistry and Petrology, [SDU]Sciences of the Universe [physics], [SDE]Environmental Sciences, Earth and Planetary Sciences (miscellaneous), Oceanography
Abstract: International audience
Published: 2023

31. Vulnerability of the savannahs of central Africa facing the last millennium climate: Insight from Lake Petpenoun (Cameroon) pollen, charcoal and carbon isotope record

Author: M. Catrain, A.-M. Lézine, B. Turcq, T. Desjardins, M. Mandeng-Yogo, F. Cetin, G. Achoundong, Variabilité à long terme du climat de l'océan (VALCO), 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), Institut d'écologie et des sciences de l'environnement de Paris (iEES Paris ), Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), National Herbarium, and ANR-18-BELM-0001,ACCEDE,Abrupt Change in Climate and Ecosystems: Where are the Tipping Points?(2018)
Subjects: [SDU]Sciences of the Universe [physics], Paleontology, Ecology, Evolution, Behavior and Systematics
Abstract: International audience
Published: 2023

32. Doppler wind measurements in Neptune’s stratosphere with ALMA

Author: Ó. Carrión-González, R. Moreno, E. Lellouch, T. Cavalié, S. Guerlet, G. Milcareck, A. Spiga, N. Clément, J. Leconte, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and ANR-20-CE49-0009,SOUND,Simulations et Observations de la dynamique atmosphérique d'Uranus et Neptune(2020)
Subjects: Earth and Planetary Astrophysics (astro-ph.EP), [PHYS]Physics [physics], Space and Planetary Science, planets and satellites, FOS: Physical sciences, Astronomy and Astrophysics, gaseous planets -radiative transfer, atmospheres -planets and satellites, Astrophysics - Earth and Planetary Astrophysics
Abstract: Neptune's tropospheric winds are among the most intense in the Solar System, but the dynamical mechanisms that produce them remain uncertain. Measuring wind speeds at different pressure levels may help understand the atmospheric dynamics of the planet. The goal of this work is to directly measure winds in Neptune's stratosphere with ALMA Doppler spectroscopy. We derived the Doppler lineshift maps of Neptune at the CO(3-2) and HCN(4-3) lines at 345.8 GHz ($\lambda$~0.87 mm) and 354.5 GHz (0.85 mm), respectively. For that, we used spectra obtained with ALMA in 2016 and recorded with a spatial resolution of ~0.37" on Neptune's 2.24" disk. After subtracting the planet solid rotation, we inferred the contribution of zonal winds to the measured Doppler lineshifts at the CO and HCN lines. We developed an MCMC-based retrieval methodology to constrain the latitudinal distribution of wind speeds. We find that CO(3-2) and HCN(4-3) lines probe the stratosphere of Neptune at pressures of $2^{+12}_{-1.8}$ mbar and $0.4^{+0.5}_{-0.3}$ mbar, respectively. The zonal winds at these altitudes are less intense than the tropospheric winds based on cloud tracking from Voyager observations. We find equatorial retrograde (westward) winds of $-180^{+70}_{-60}$ m/s for CO, and $-190^{+90}_{-70}$ m/s for HCN. Wind intensity decreases towards mid-latitudes, and wind speeds at 40$^\circ$S are $-90^{+50}_{-60}$ m/s for CO, and $-40^{+60}_{-80}$ m/s for HCN. Wind speeds become 0 m/s at about 50$^\circ$S, and we find that the circulation reverses to a prograde jet southwards of 60$^\circ$S. Overall, our direct stratospheric wind measurements match previous estimates from stellar occultation profiles and expectations based on thermal wind equilibrium. These are the first direct Doppler wind measurements performed on the Icy Giants, opening a new method to study and monitor their stratospheric dynamics., Comment: Accepted for publication in A&A Letters on 10/05/2023. 8 pages, 1 Table, 5 Figures
Published: 2023

33. Open science resources from the Tara Pacific expedition across coral reef and surface ocean ecosystems

Author: Fabien Lombard, Guillaume Bourdin, Stéphane Pesant, Sylvain Agostini, Alberto Baudena, Emilie Boissin, Nicolas Cassar, Megan Clampitt, Pascal Conan, Ophélie Da Silva, Céline Dimier, Eric Douville, Amanda Elineau, Jonathan Fin, J. Michel Flores, Jean François Ghiglione, Benjamin C.C. Hume, Laetitia Jalabert, Seth G. John, Rachel L. Kelly, Ilan Koren, Yajuan Lin, Dominique Marie, Ryan McMinds, Zoé Mériguet, Nicolas Metzl, David A. Paz-García, Maria Luiza Pedrotti, Julie Poulain, Mireille Pujo-Pay, Joséphine Ras, Gilles Reverdin, Sarah Romac, Alice Rouan, Eric Röttinger, Assaf Vardi, Christian R. Voolstra, Clémentine Moulin, Guillaume Iwankow, Bernard Banaigs, Chris Bowler, Colomban de Vargas, Didier Forcioli, Paola Furla, Pierre E. Galand, Eric Gilson, Stéphanie Reynaud, Shinichi Sunagawa, Matthew B. Sullivan, Olivier Thomas, Romain Troublé, Rebecca Vega Thurber, Patrick Wincker, Didier Zoccola, Denis Allemand, Serge Planes, Emmanuel Boss, Gaby Gorsky, Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Global Oceans Systems Ecology & Evolution - Tara Oceans (GOSEE), Université de Perpignan Via Domitia (UPVD)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Aix Marseille Université (AMU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université d'Évry-Val-d'Essonne (UEVE)-Université de Toulon (UTLN)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche pour le Développement (IRD [France-Nord])-Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay)-European Molecular Biology Laboratory (EMBL)-École Centrale de Nantes (Nantes Univ - ECN), Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Université australe du Chili, Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), University of Maine, European Molecular Biology Laboratory [Hinxton], Shimoda Marine Research Center, Université de Tsukuba = University of Tsukuba, Centre de recherches insulaires et observatoire de l'environnement (CRIOBE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Nicholas School of the Environment, Duke University [Durham], Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche sur le Cancer et le Vieillissement (IRCAN), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), Institut Fédératif de Recherche - Ressources Marines (IFR MARRES), Université Côte d'Azur (UCA), Laboratoire International Associé Réponse des Organismes et Populations face au Stress Environnemental - Université Côte d’Azur - Centre Scientifique de Monaco (LIA ROPSE), Université Côte d’Azur - Centre Scientifique de Monaco, Laboratoire d'Océanographie Microbienne (LOMIC), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Observatoire océanologique de Banyuls (OOB), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), OSU Stations marines (STAMAR), Sorbonne Université (SU)-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), 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), Cycles biogéochimiques marins : processus et perturbations (CYBIOM), 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), Weizmann Institute of Science [Rehovot, Israël], Universität Konstanz, Department of Earth Sciences [USC Los Angeles], University of Southern California (USC), Station biologique de Roscoff (SBR), Maison de la Modélisation, de la Simulation et des Interactions [Sophia-Antipolis] (MSI), Oregon State University (OSU), Centro de Investigaciones Biologicas del Noroeste [Mexico] (CONACYT-CIBNOR), Consejo Nacional de Ciencia y Tecnología [Mexico] (CONACYT), Institut de Biologie François JACOB (JACOB), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Processus et interactions de fine échelle océanique (PROTEO), Tara Ocean Foundation, Institut de biologie de l'ENS Paris (IBENS), Département de Biologie - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ecogéochimie des environnements benthiques (LECOB), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Observatoire océanologique de Banyuls (OOB), Centre Scientifique de Monaco (CSM), Ohio State University [Columbus] (OSU), Institute of Microbiology and Swiss Institute of Bioinformatics, Martin Ryan Institute, and National University of Ireland [Galway] (NUI Galway)
Subjects: [SDU]Sciences of the Universe [physics], Ecosystem ecology, Biodiversity
Abstract: The Tara Pacific expedition (2016-2018) sampled coral ecosystems around 32 islands in the Pacific Ocean and the ocean surface waters at 249 locations, resulting in the collection of nearly 58,000 samples. The expedition was designed to systematically study warm coral reefs and included the collection of corals, fish, plankton, and seawater samples for advanced biogeochemical, molecular, and imaging analysis. Here we provide a complete description of the sampling methodology, and we explain how to explore and access the different datasets generated by the expedition. Environmental context data were obtained from taxonomic registries, gazetteers, almanacs, climatologies, operational biogeochemical models, and satellite observations. The quality of the different environmental measures has been validated not only by various quality control steps but also through a global analysis allowing the comparison with known environmental large-scale structures. Such a wide released datasets opens the perspective to address a wide range of scientific questions.
Published: 2023

34. Copepods' true colors: astaxanthin pigmentation as an indicator of fitness

Author: Vilgrain, Laure, Maps, Frédéric, Basedow, Sünnje, Trudnowska, Emilia, Madoui, Mohammed‐Amin, Niehoff, Barbara, Ayata, Sakina-Dorothée, Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Takuvik Joint International Laboratory ULAVAL-CNRS, Université Laval [Québec] (ULaval)-Institut national des sciences de l'Univers (INSU - CNRS)-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), The Arctic University of Norway [Tromsø, Norway] (UiT), Institute of Oceanology, Polish Academy of Sciences (IO-PAN), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Processus et interactions de fine échelle océanique (PROTEO), 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)-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))
Subjects: [SDU]Sciences of the Universe [physics]
Abstract: International audience; Pigmentation is often overlooked in zooplankton, since these organisms are mostly colorless to fit the translucid water medium. However, one of the dominant zooplankton taxa in aquatic ecosystems-copepods-often show a bright red-orange or blue coloration owing to the accumulation of carotenoid pigments in some parts of their bodies. Even though there are many functional traits describing copepod's performance (e.g., size, feeding, and reproductive modes), it is surprising that the role of such a simple and visible trait as coloration has not been studied in a coherent manner yet. Here, by reviewing 95 studies, we demonstrate that carotenoid-based pigmentation (mainly caused by astaxanthin molecules) is a widespread functional trait in freshwater and marine copepods. We propose a way to disentangle the complex and thus intriguing patterns of pigment expression along latitudinal and altitudinal gradients, addressing its relationship to diet quality and quantity, temperature, ultraviolet radiation stress, predation pressure, lipid metabolism, and reproduction. We show that large-scale variations in pigmentation are difficult to tackle because of the fundamental plasticity of this trait at short time scales (i.e., hours, days), and the most recent information about carotenoid bioconversion are addressed (genes and enzyme identification, and influence of microbiota). From this literature review, we hypothesize that pigments play a
Published: 2023

35. Combined physical and biogeochemical assessment of mesoscale eddy parameterisations in ocean models: eddy induced advection at non-eddying resolutions

Author: X. Ruan, D. Couespel, M. Lévy, J. Li, J. Mak, Y. Wang, Hong Kong University of Science and Technology (HKUST), NORCE Norwegian Research Center, Processus et interactions de fine échelle océanique (PROTEO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and Chanel Research Chair of ENS-PSL
Subjects: Atmospheric Science, climate change, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Computer Science (miscellaneous), numerical modelling, Geotechnical Engineering and Engineering Geology, Oceanography, mesoscale eddy parameterisation, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, biophysical interactions
Abstract: International audience; Ocean components of Earth System Models employed for climate projections do not routinely resolve mesoscale eddies for computational cost reasons, and the associated subgrid processes are still parameterised. While the performance of physics parameterisations in a numerical ocean model is normally assessed by examining the associated physical responses, biogeochemical responses are also important but often treated separately. Given recent advances in mesoscale eddy parameterisations, specifically for the eddy induced advection, this work systematically explores the joint consequences for physical as well as biogeochemical responses brought about by a more updated proposal for the eddy induced velocity coefficient, in the context of an idealised ocean relevant model. Relative to a high resolution mesoscale eddy resolving model, the more updated mesoscale eddy parameterisation is able to capture aspects of the model truth in the physical responses. The biogeochemistry response is however rather more subtle, where a 'better' response with the conventional eddy parameterisation with a constant coefficient could arise from a physically inconsistent response, while a parameterisation that improves the bulk physical response may still fall short in its biogeochemical response. The present work highlights a need to assess both physical and biogeochemical aspects when judging the performance of eddy parameterisations, and additionally provides some important baseline model sensitivities that future assessments employing other parameterisations or in more complex settings could compare against.
Published: 2023

36. 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

37. Parametric PDEs solvers, uncertainty quantification and parameter estimation

Author: Riffaud, Sébastien, Lombardi, Damiano, Fernández, Miguel, COmputational Mathematics for bio-MEDIcal Applications (COMMEDIA), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), and Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: Blood flow modeling, Parameter estimation, [MATH]Mathematics [math], Low-rank methods
Abstract: International audience; This work has been motivated by data assimilation applications in biomedical engineering. In all these applications, a set of partial noisy observations of the system state have to be exploited in order to assess, at best, a set of quantities of interest. We focus here on the applications in which the state evolution can be described by a system of parametric PDEs, and the measurements have to be used in order to estimate the parameters values. Two major difficulties need to be faced. The first one is identifiability: given the observations, can we estimate the parameters? The second one is related to the estimation itself: even when considering linear PDEs, the solution depends potentially in a highly non-linear way on the parameters. When using a variational formulation this often leads to a non-linear non-convex optimisation to be solved, involving a prohibitive computational burden.The goal of the present work is to propose a framework to perform parameter estimation, accounting automatically for identifiability (by using a Bayesian formulation), and for the uncertainties. It can be seen as a possible discretisation of a Bayesian filter. The main idea consists in trying to approximate the system solution as function of space-time and parameters variables. This is done by introducing an efficient low-rank solver.Instead of keeping the discretisation of the parameters domain fixed, we make it evolved based on the system observations. This adaptation task is performed thanks to a Metropolis Hastings algorithm, enabled by a reduced-order interpolator which we can build thanks to the parametric solution. The interplay between the reduced-order interpolator and the parametric solver is crucial to get efficiency: the reduced-order interpolator makes the adaptation fast, getting a more adapted discretisation in parameters contributes to keep the cost of the parametric solver moderate, the parametric solver makes the construction of the ROM interpolator fast. As a result, we can compute, efficiently, mean, standard deviation (other moments or information related quantities) of the posterior distribution of the parameters and the statistics of the system solution. Several test-cases are presented.
Published: 2023

38. Stability of implicit neural networks for long-term forecasting in dynamical systems

Author: Migus, Leon, Salomon, Julien, Gallinari, Patrick, Numerical Analysis, Geophysics and Ecology (ANGE), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Sorbonne Université (SU), Machine Learning and Information Access (MLIA), Institut des Systèmes Intelligents et de Robotique (ISIR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Criteo AI Lab, and Criteo [Paris]
Subjects: FOS: Computer and information sciences, [PHYS]Physics [physics], Computer Science - Machine Learning, Computer Science - Artificial Intelligence, Forecasting dynamical systems, Partial Differential Equations, Numerical Analysis (math.NA), Machine Learning (cs.LG), Artificial Intelligence (cs.AI), Deep Learning, FOS: Mathematics, [INFO]Computer Science [cs], Mathematics - Numerical Analysis, [MATH]Mathematics [math], Stability, Numerical analysis
Abstract: Forecasting physical signals in long time range is among the most challenging tasks in Partial Differential Equations (PDEs) research. To circumvent limitations of traditional solvers, many different Deep Learning methods have been proposed. They are all based on auto-regressive methods and exhibit stability issues. Drawing inspiration from the stability property of implicit numerical schemes, we introduce a stable auto-regressive implicit neural network. We develop a theory based on the stability definition of schemes to ensure the stability in forecasting of this network. It leads us to introduce hard constraints on its weights and propagate the dynamics in the latent space. Our experimental results validate our stability property, and show improved results at long-term forecasting for two transports PDEs., ICLR 2023 Workshop on Physics for Machine Learning
Published: 2023

39. Slowing of the ocean’s deep breath

Author: Casimir de Lavergne, 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]Sciences of the Universe [physics], Environmental Science (miscellaneous), Social Sciences (miscellaneous)
Abstract: International audience; The deepest reaches of the ocean are ventilated by sinking of cold and relatively saline seawater around Antarctica. Observations from the Australian sector of the Southern Ocean reveal a decline in sinking and abyssal ventilation, linked to dropping ocean salinity on the Antarctic shelf.
Published: 2023

40. Existence of optimal domains for the helicity maximisation problem among domains satisfying a uniform ball condition

Author: Gerner, Wadim, Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Control And GEometry (CaGE ), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and This work has been supported by the Inria AEX StellaCage.
Subjects: Plasma fusion, FOS: Physical sciences, Mathematical Physics (math-ph), 35Q31, 35Q35, 35Q85, 49J35, 49Q10, 76W05, Mathematics - Spectral Theory, Magnetohydrodynamics, Helicity, 2020MSC: 35Q31, 35Q35, 35Q85, 49J35, 49Q10, 76W05, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], FOS: Mathematics, [MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP], Spectral Theory (math.SP), Isoperimetric problems, Mathematical Physics
Abstract: In the present work we present a general framework which guarantees the existence of optimal domains for isoperimetric problems within the class of $C^{1,1}$-regular domains satisfying a uniform ball condition as long as the desired objective function satisfies certain properties. We then verify that the helicity isoperimetric problem studied by Cantarella, DeTurck, Gluck and Teytel in \cite{CDGT002} satisfies the conditions of our framework and hence establish the existence of optimal domains within the given class of domains. We additionally use the same framework to prove the existence of optimal domains among uniform $C^{1,1}$-domains for a first curl eigenvalue problem which has been studied recently for other classes of domains in \cite{EGPS23}., 11 pages, comments welcome!
Published: 2023

41. Modulations in the Indian Summer Monsoon–ENSO teleconnections by the North Tropical Atlantic

Author: K. P. Sooraj, Ajinkya M. Aswale, P. Swapna, P. Terray, N. S. Sandeep, Indian Institute of Tropical Meteorology (IITM), Savitribai Phule Pune University [India], Océan et variabilité du climat (VARCLIM), 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: Atmospheric Science, Coupled model simulations, [SDU]Sciences of the Universe [physics], NTA SST, NTA-ENSO-ISM association, ISM response, ENSO, Asymmetric ENSO-ISM response
Abstract: International audience; North Tropical Atlantic Sea Surface Temperature (i.e., NTA SST) anomalies emerge as a key-driver of the whole El Niño Southern Oscillation-Indian Summer Monsoon (ENSO-ISM) system. However, as the underlying physical mechanisms are not yet well understood, this study made an attempt to have deeper insights on the role of the NTA SST variability on the ISM, ENSO and their mutual relationships. The evidences from observations and a Pi-Control coupled simulation demonstrate the pronounced biennial nature of the NTA-ENSO-ISM system and suggest the precursory role of the NTA SSTs in this biennial ENSO-ISM system. As the cause-and-effect relationships are difficult to disentangle, ensembles of short coupled sensitivity experiments are conducted by imposing observed warm (cold) SST anomalies over NTA. These 1-year simulations start from various January initial conditions corresponding to strong El Niño (La Niña) events as identified from Pi-Control and subsequently impose warm (cold) SST anomalies over the NTA region after the El Niño (La Niña) peak in January. The sensitivity experiments support the hypothesis of a key role of NTA SSTs in the reversal of the ENSO conditions through their capacitor effect. They further illustrate the nonlinear characteristics of this system as cold NTA SST perturbations are more influential than warm NTA SSTs. This non-linearity brings up new perspectives on the NTA-ENSO-ISM system, as it is further reflected in the asymmetric response in the simulated ENSO-ISM, with the cold NTA perturbations initiated from the La Niña conditions showing a stronger anomalous ISM response during boreal summer, which is in contrast with the feeble ISM response in the warm NTA perturbations experiment using the El Niño initial conditions. This non-linearity of NTA-ENSO-ISM has larger implications in a global warming scenario, as the climate variability over NTA region is projected to intensify in the future.
Published: 2023

42. Hyperbolic reduced model for Vlasov-Poisson equation with Fokker-Planck collision

Author: Franck, Emmanuel, Lannabi, Ibtissem, Nasseri, Youssouf, Navoret, Laurent, Parasiliti, Giuseppe, Steimer, Guillaume, Institut de Recherche Mathématique Avancée (IRMA), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), TOkamaks and NUmerical Simulations (TONUS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Inria Nancy - Grand Est, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), Laboratoire de Mathématiques et de leurs Applications [Pau] (LMAP), Université de Pau et des Pays de l'Adour (UPPA)-Centre National de la Recherche Scientifique (CNRS), Numerical Analysis, Geophysics and Ecology (ANGE), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and Sorbonne Université (SU)
Subjects: [MATH]Mathematics [math]
Abstract: This paper proposes a reduced model to simulate the one-dimensional Vlasov-Poisson equation with the non-linear Fokker-Planck operator. The model provides the space-time dynamics of a few macroscopic quantities constructed following the Reduced Order Method (ROM) in the velocity variable: the compression is thus applied to the semi-discretization of the Vlasov equation. To gain efficiency, a Discrete Empirical Interpolation Method (DEIM) is applied to the compressed non-linear Fokker-Planck operator. The size of the resulting reduced model is chosen empirically according to the Knudsen number. Furthermore, we propose a correction to the reduced collision operator that ensures the reduced moments to satisfy an Euler-type system. Numerical simulations of the reduced model show that the model can capture the plasma dynamics in different collisional regimes and initial conditions at a low cost.
Published: 2023

43. Numerical analysis of an incompressible soft material poromechanics model using T-coercivity

Author: Barré, Mathieu, Grandmont, Céline, Moireau, Philippe, Laboratoire de mécanique des solides (LMS), École polytechnique (X)-Mines Paris - PSL (École nationale supérieure des mines de Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Mathematical and Mechanical Modeling with Data Interaction in Simulations for Medicine (M3DISIM), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Mines Paris - PSL (École nationale supérieure des mines de Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Inria Saclay - Ile de France, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), COmputational Mathematics for bio-MEDIcal Applications (COMMEDIA), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Département de Mathématique [Bruxelles] (ULB), Faculté des Sciences [Bruxelles] (ULB), Université libre de Bruxelles (ULB)-Université libre de Bruxelles (ULB), and Sorbonne Université (SU)
Subjects: inf-sup stability, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], mixture theory, energy preserving scheme, total discretization, [MATH.MATH-NA]Mathematics [math]/Numerical Analysis [math.NA], incompressible limit
Abstract: This article is devoted to the numerical analysis of the full discretization of a generalized poromechanical model resulting from the linearization of an initial model fitted to soft tissue perfusion. Our strategy here is based on the use of energy-based estimates and T-coercivity methods, so that the numerical analysis benefits from the essential tools used in the existence analysis of the continuous-time and continuous-space formulation. In particular, our T-coercivity strategy allows us to obtain the necessary inf-sup condition for the global system from the inf-sup condition restricted to a subsystem having the same structure as the Stokes problem. This allows us to prove that any finite element pair adapted to the Stokes problem is also suitable for this global poromechanical model regardless of porosity and permeability, generalizing previous results from the literature studying this model.
Published: 2023

44. Observations of the Perseverance rover at the Jezero crater delta front using the SuperCam instrument

Author: Mangold, Nicolas, Caravaca, Gwénaël, Dehouck, Erwin, Beyssac, Olivier, Beck, Pierre, Clavé, Elise, Cousin, Agnès, Dromart, Gilles, Forni, Olivier, Fouchet, Thierry, Gasnault, Olivier, Gupta, Sanjeev, Le Mouélic, Stéphane, Mandon, Lucia, Maurice, Sylvestre, Meslin, Pierre-Yves, Quantin-Nataf, Cathy, Royer, Clément, Wiens, Roger, Team, The Supercam, Laboratoire de Planétologie et Géosciences [UMR_C 6112] (LPG), Université d'Angers (UA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Nantes université - UFR des Sciences et des Techniques (Nantes univ - UFR ST), Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), Institut de recherche en astrophysique et planétologie (IRAP), 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), 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), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), 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)-Météo-France, Centre d'Etudes Lasers Intenses et Applications (CELIA), Université de Bordeaux (UB)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Department of Earth Science and Engineering [Imperial College London], Imperial College London, Division of Geological and Planetary Sciences [Pasadena], California Institute of Technology (CALTECH), Purdue University [West Lafayette], European Geosciences Union, and EGU
Subjects: jezero crater, delta, [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology, SuperCam, [SDU]Sciences of the Universe [physics], [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Mars 2020, perseverance, Mars, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Abstract: International audience; The Perseverance rover landed on the floor of Jezero crater in February 2021. The initial set of images taken from the landing site of the residual butte Kodiak showed a deltaic architecture consistent with a paleolake, but at a level ~100 m lower than expected, suggestive of a closed lake system. After spending ~1 year studying the crater floor, the rover reached the front of the deltaic fan in April 2022. Here, we report observations of the facies, structure and composition of these sedimentary deposits using the SuperCam instrument. SuperCam can take images for texture analysis with the Remote Micro-Imager (RMI), visible and infrared reflectance (VISIR) spectra as well as Raman spectra for mineralogical analysis, and data from laser induced breakdown spectroscopy (LIBS) for chemical analysis. The rover investigated the basal strata of the delta along two traverses at the SE of the delta front. The transition between the crater floor and the delta is not well determined due to regolith and strongly degraded outcrops, and is currently under assessment. The ~20 m thick basal layers that are well-visible on orbital data consist of fine-grained sandstones and siltstones deposited in sub-horizontal planar beds with millimeter thick laminations. These deposits display a substantial alteration highlighted by the detection of both sulfates and phyllosilicates, with exception of local boulders of igneous texture lacking alteration. Texture and composition are both consistent with a quiet regime of deposition such as in lake deposits or distal delta slopes. These beds are considered of topmost importance for sample return and were cored in two locations. Pebbly sandstones and conglomerates with pebbles limited to a few centimeters are observed immediately above these strata. The texture is matrix-supported suggesting an emplacement through gravity sliding or turbidity flows below water rather than fluvial deposition. The composition is more variable than in underlying finer-grained beds and includes local carbonate detections. Uppermost deposits have not been reached by the rover yet, but have been analyzed remotely by RMI images, and VISIR for some of them. They consist of cross-bedded sandstones and conglomerates in all locations of the delta front. The diversity in texture of these deposits suggests a variability in depositional regimes including high-energy floods, either during the lacustrine phase, or subsequently. Boulders present within these layers are rounded suggesting a substantial abrasion by fluvial transport. These boulders are also interesting targets for sampling distant crustal rocks. The top of the delta will be analyzed and sampled along the traverse of the rover in 2023.
Published: 2023

45. 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

46. Nonlocal Cahn-Hilliard equation with degenerate mobility: Incompressible limit and convergence to stationary states

Author: Elbar, Charles, Perthame, Benoît, Poiatti, Andrea, Skrzeczkowski, Jakub, Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Modelling and Analysis for Medical and Biological Applications (MAMBA), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Dipartimento di Matematica [Politecnico Milano] (POLIMI), Politecnico di Milano [Milan] (POLIMI), Faculty of Mathematics, Informatics, and Mechanics [Warsaw] (MIMUW), University of Warsaw (UW), Institute of Mathematics [Warsaw], Polish Academy of Sciences (PAN), and J.S. was supported by the National Science Center grant 2017/26/M/ST1/00783. A.P. has been partially funded by MIUR-PRIN research grant n. 2020F3NCPX and is also member of Gruppo Nazionale per l’Analisi Matematica, la Probabilità e le loro Applicazioni (GNAMPA), Istituto Nazionale di Alta Matematica (INdAM)
Subjects: Mathematics - Analysis of PDEs, Asymptotic analysis, FOS: Mathematics, Convergence to equilibrium, [MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP], Hele-Shaw equations, 35B40, 35B45, 35G20, 35Q92, Incompressible limit, 2010 MSC: 35B40, 35B45, 35G20, 35Q92, Analysis of PDEs (math.AP), Degenerate Cahn-Hilliard equation
Abstract: The link between compressible models of tissue growth and the Hele-Shaw free boundary problem of fluid mechanics has recently attracted a lot of attention. In most of these models, only repulsive forces and advection terms are taken into account. In order to take into account long range interactions, we include for the first time a surface tension effect by adding a nonlocal term which leads to the degenerate nonlocal Cahn-Hilliard equation, and study the incompressible limit of the system. The degeneracy and the source term are the main difficulties. Our approach relies on a new L^infty estimate obtained by De Giorgi iterations and on a uniform control of the energy despite the source term. We also prove the long-term convergence to a single constant stationary state of any weak solution using entropy methods, even when a source term is present. Our result shows that the surface tension in the nonlocal (and even local) Cahn-Hilliard equation will not prevent the tumor from completely invading the domain., 29 pages + appendix + bibliography
Published: 2023

47. Non-perturbative non-Gaussianity and primordial black holes

Author: Andrew Gow, Hooshyar Assadullahi, Joseph H. P. Jackson, Kazuya Koyama, Vincent Vennin, David Wands, Institute of Cosmology and Gravitation [Portsmouth] (ICG), University of Portsmouth, Cosmologie et Gravitation, 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)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Département de Physique de l'ENS-PSL, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: density, Cosmology and Nongalactic Astrophysics (astro-ph.CO), perturbation, formation, FOS: Physical sciences, slow-roll approximation, General Physics and Astronomy, General Relativity and Quantum Cosmology (gr-qc), nonperturbative, General Relativity and Quantum Cosmology, mass spectrum, statistics, curvature, non-Gaussianity, black hole, [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], primordial, distribution function, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], enhancement, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: We present a non-perturbative method for calculating the abundance of primordial black holes given an arbitrary one-point probability distribution function for the primordial curvature perturbation, $P(\zeta)$. A non-perturbative method is essential when considering non-Gaussianities that cannot be treated using a conventional perturbative expansion. To determine the full statistics of the density field, we relate $\zeta$ to a Gaussian field by equating the cumulative distribution functions. We consider two examples: a specific local-type non-Gaussian distribution arising from ultra slow roll models, and a general piecewise model for $P(\zeta)$ with an exponential tail. We demonstrate that the enhancement of primordial black hole formation is due to the intermediate regime, rather than the far tail. We also show that non-Gaussianity can have a significant impact on the shape of the primordial black hole mass distribution., Comment: 9 pages, 2 figures; Version 3: matches published version
Published: 2023

48. Southern ocean carbon and heat impact on climate

Author: Sallée, Jean-Baptiste, Abrahamsen, E. P., Allaigre, C., Auger, Matthis, Ayres, H., Badhe, R., Boutin, Jacqueline, Brearley, J. A., de Lavergne, Casimir, ten Doeschate, A. M. M., Droste, E. S., Du Plessis, M. D., Ferreira, D., Giddy, I. S., Gülk, B., Gruber, N., Hague, M., Hoppema, M., Josey, S. A., Kanzow, T., Kimmritz, M., Lindeman, M. R., Llanillo, P. J., Lucas, N. S., Madec, Gurvan, Marshall, D. P., Meijers, A. J. S., Meredith, M. P., Mohrmann, M., Monteiro, P. M. S., Mosneron Dupin, Cosme, Naeck, Kirtana, Narayanan, A., Naveira Garabato, A. C., Nicholson, S. -A., Novellino, A., Ödalen, M., Østerhus, S., Park, W., Patmore, R. D., Piedagnel, Évéa, Roquet, Fabien, Rosenthal, H. S., Roy, T., Saurabh, Rathore, Silvy, Yona, Spira, T., Steiger, Nadine, Styles, A. F., Swart, S., Vogt, Linus, Ward, B., Zhou, S., 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), Nucleus for European Modeling of the Ocean (NEMO R&D ), Océan et variabilité du climat (VARCLIM), and European Project: 821001,SO-CHIC(2019)
Subjects: [SDU]Sciences of the Universe [physics]
Abstract: International audience; The Southern Ocean greatly contributes to the regulation of the global climate by controlling important heat and carbon exchanges between the atmosphere and the ocean. Rates of climate change on decadal timescales are therefore impacted by oceanic processes taking place in the Southern Ocean, yet too little is known about these processes. Limitations come both from the lack of observations in this extreme environment and its inherent sensitivity to intermittent processes at scales that are not well captured in current Earth system models. The Southern Ocean Carbon and Heat Impact on Climate programme was launched to address this knowledge gap, with the overall objective to understand and quantify variability of heat and carbon budgets in the Southern Ocean through an investigation of the key physical processes controlling exchanges between the atmosphere, ocean and sea ice using a combination of observational and modelling approaches. Here, we provide a brief overview of the programme, as well as a summary of some of the scientific progress achieved during its first half. Advances range from new evidence of the importance of specific processes in Southern Ocean ventilation rate (e.g. storm-induced turbulence, sea-ice meltwater fronts, wind-induced gyre circulation, dense shelf water formation and abyssal mixing) to refined descriptions of the physical changes currently ongoing in the Southern Ocean and of their link with global climate. This article is part of a discussion meeting issue `Heat and carbon uptake in the Southern Ocean: the state of the art and future priorities'.
Published: 2023

49. Analysis and numerical simulation of a generalized compressible Cahn-Hilliard-Navier-Stokes model with friction effects

Author: Elbar, Charles, Poulain, Alexandre, Sorbonne Université (SU), Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Modelling and Analysis for Medical and Biological Applications (MAMBA), Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire Jacques-Louis Lions (LJLL (UMR_7598)), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université de Lille, Laboratoire Paul Painlevé (LPP), and Université de Lille-Centre National de la Recherche Scientifique (CNRS)
Subjects: 35B40, 35B45, 35G20, 35Q35, 35Q92, 65M08, Mathematics - Analysis of PDEs, Scalar Auxiliary Variable method, Asymptotic analysis, FOS: Mathematics, Numerical simulations, 35B40, 35B45, 35G20, 35Q35, 35Q92, 65M08, Mathematical modeling, Mathematics - Numerical Analysis, Numerical Analysis (math.NA), [MATH]Mathematics [math], Analysis of PDEs (math.AP), Navier-Stokes equation
Abstract: Motivated by the mathematical modeling of tumor invasion in healthy tissues, we propose a generalized compressible diphasic Navier-Stokes Cahn-Hilliard model that we name G-NSCH. We assume that the two phases of the fluid represent two different populations of cells: cancer cells and healthy tissue. We include in our model possible friction and proliferation effects. The model aims to be as general as possible to study the possible mechanical effects playing a role in the invasive growth of a tumor. In the present work, we focus on the analysis and numerical simulation of the G-NSCH model. Our G-NSCH system is derived rigorously and satisfies the basic mechanics of fluids and the thermodynamics of particles. Under simplifying assumptions, we prove the existence of global weak solutions. We also propose a structure-preserving numerical scheme based on the scalar auxiliary variable method to simulate our system and present some numerical simulations validating the properties of the numerical scheme and illustrating the solutions of the G-NSCH model., Comment: 29 pages + appendix + bibliography
Published: 2023

50. Semi‐Automatic Tuning of Coupled Climate Models With Multiple Intrinsic Timescales: Lessons Learned From the Lorenz96 Model

Author: Redouane Lguensat, Julie Deshayes, Homer Durand, Venkatramani Balaji, 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), 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)), 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), 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), Princeton University, NOAA Geophysical Fluid Dynamics Laboratory (GFDL), National Oceanic and Atmospheric Administration (NOAA), and ANR-17-MPGA-0010,HRMES,High-Resolution Modeling of the Earth System(2017)
Subjects: FOS: Computer and information sciences, Global and Planetary Change, Physics - Atmospheric and Oceanic Physics, Computer Science - Machine Learning, [SDU]Sciences of the Universe [physics], Atmospheric and Oceanic Physics (physics.ao-ph), General Earth and Planetary Sciences, Environmental Chemistry, FOS: Physical sciences, Machine Learning (cs.LG)
Abstract: The objective of this study is to evaluate the potential for History Matching (HM) to tune a climate system with multi-scale dynamics. By considering a toy climate model, namely, the two-scale Lorenz96 model and producing experiments in perfect-model setting, we explore in detail how several built-in choices need to be carefully tested. We also demonstrate the importance of introducing physical expertise in the range of parameters, a priori to running HM. Finally we revisit a classical procedure in climate model tuning, that consists of tuning the slow and fast components separately. By doing so in the Lorenz96 model, we illustrate the non-uniqueness of plausible parameters and highlight the specificity of metrics emerging from the coupling. This paper contributes also to bridging the communities of uncertainty quantification, machine learning and climate modeling, by making connections between the terms used by each community for the same concept and presenting promising collaboration avenues that would benefit climate modeling research., Submission to JAMES journal (AGU), added link to code
Published: 2023

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