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6 results on '"Département des sciences de la terre et de l'atmosphère [Montréal] (SCTA)"'

1. A multi-model CMIP6-PMIP4 study of Arctic sea ice at 127 ka: sea ice data compilation and model differences

Author

M. Kageyama, L. C. Sime, M. Sicard, M.-V. Guarino, A. de Vernal, R. Stein, D. Schroeder, I. Malmierca-Vallet, A. Abe-Ouchi, C. Bitz, P. Braconnot, E. C. Brady, J. Cao, M. A. Chamberlain, D. Feltham, C. Guo, A. N. LeGrande, G. Lohmann, K. J. Meissner, L. Menviel, P. Morozova, K. H. Nisancioglu, B. L. Otto-Bliesner, R. O'ishi, S. Ramos Buarque, D. Salas y Melia, S. Sherriff-Tadano, J. Stroeve, X. Shi, B. Sun, R. A. Tomas, E. Volodin, N. K. H. Yeung, Q. Zhang, Z. Zhang, W. Zheng, T. Ziehn, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modélisation du climat (CLIM), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), British Antarctic Survey (BAS), Natural Environment Research Council (NERC), Département des sciences de la terre et de l'atmosphère [Montréal] (SCTA), Université du Québec à Montréal = University of Québec in Montréal (UQAM), Centre de recherche sur la dynamique du système Terre (GEOTOP), Université de Montréal (UdeM)-McGill University = Université McGill [Montréal, Canada]-École Polytechnique de Montréal (EPM)-Concordia University [Montreal]-Université du Québec à Rimouski (UQAR)-Université du Québec à Montréal = University of Québec in Montréal (UQAM)-Université du Québec en Abitibi-Témiscamingue (UQAT), Centre for Polar Observation and Modelling (CPOM), Atmosphere and Ocean Research Institute [Kashiwa-shi] (AORI), The University of Tokyo (UTokyo), Department of Atmospheric Sciences [Seattle], University of Washington [Seattle], Modelling the Earth Response to Multiple Anthropogenic Interactions and Dynamics (MERMAID), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Université de 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)-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), École Polytechnique de Montréal (EPM)-McGill University = Université McGill [Montréal, Canada]-Université de Montréal (UdeM)-Université du Québec en Abitibi-Témiscamingue (UQAT)-Université du Québec à Rimouski (UQAR)-Concordia University [Montreal]-Université du Québec à Montréal = University of Québec in Montréal (UQAM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
010506 paleontology, 010504 meteorology & atmospheric sciences, Stratigraphy, lcsh:Environmental protection, 01 natural sciences, lcsh:Environmental pollution, Sea ice, Cryosphere, lcsh:TD169-171.8, [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology, Sea ice concentration, lcsh:Environmental sciences, 0105 earth and related environmental sciences, lcsh:GE1-350, Global and Planetary Change, Coupled model intercomparison project, geography, geography.geographical_feature_category, Paleontology, Arctic ice pack, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, Paleoclimate Modelling Intercomparison Project, Interglacial, lcsh:TD172-193.5, Climate model, Geology
Abstract

The Last Interglacial period (LIG) is a period with increased summer insolation at high northern latitudes, which results in strong changes in the terrestrial and marine cryosphere. Understanding the mechanisms for this response via climate modelling and comparing the models' representation of climate reconstructions is one of the objectives set up by the Paleoclimate Modelling Intercomparison Project for its contribution to the sixth phase of the Coupled Model Intercomparison Project. Here we analyse the results from 16 climate models in terms of Arctic sea ice. The multi-model mean reduction in minimum sea ice area from the pre industrial period (PI) to the LIG reaches 50 % (multi-model mean LIG area is 3.20×106 km2, compared to 6.46×106 km2 for the PI). On the other hand, there is little change for the maximum sea ice area (which is 15–16×106 km2 for both the PI and the LIG. To evaluate the model results we synthesise LIG sea ice data from marine cores collected in the Arctic Ocean, Nordic Seas and northern North Atlantic. The reconstructions for the northern North Atlantic show year-round ice-free conditions, and most models yield results in agreement with these reconstructions. Model–data disagreement appear for the sites in the Nordic Seas close to Greenland and at the edge of the Arctic Ocean. The northernmost site with good chronology, for which a sea ice concentration larger than 75 % is reconstructed even in summer, discriminates those models which simulate too little sea ice. However, the remaining models appear to simulate too much sea ice over the two sites south of the northernmost one, for which the reconstructed sea ice cover is seasonal. Hence models either underestimate or overestimate sea ice cover for the LIG, and their bias does not appear to be related to their bias for the pre-industrial period. Drivers for the inter-model differences are different phasing of the up and down short-wave anomalies over the Arctic Ocean, which are associated with differences in model albedo; possible cloud property differences, in terms of optical depth; and LIG ocean circulation changes which occur for some, but not all, LIG simulations. Finally, we note that inter-comparisons between the LIG simulations and simulations for future climate with moderate (1 % yr−1) CO2 increase show a relationship between LIG sea ice and sea ice simulated under CO2 increase around the years of doubling CO2. The LIG may therefore yield insight into likely 21st century Arctic sea ice changes using these LIG simulations.

Published
2021
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2. Overview paper: New insights into aerosol and climate in the Arctic

Author

J. P. D. Abbatt, W. R. Leaitch, A. A. Aliabadi, A. K. Bertram, J.-P. Blanchet, A. Boivin-Rioux, H. Bozem, J. Burkart, R. Y. W. Chang, J. Charette, J. P. Chaubey, R. J. Christensen, A. Cirisan, D. B. Collins, B. Croft, J. Dionne, G. J. Evans, C. G. Fletcher, M. Galí, R. Ghahremaninezhad, E. Girard, W. Gong, M. Gosselin, M. Gourdal, S. J. Hanna, H. Hayashida, A. B. Herber, S. Hesaraki, P. Hoor, L. Huang, R. Hussherr, V. E. Irish, S. A. Keita, J. K. Kodros, F. Köllner, F. Kolonjari, D. Kunkel, L. A. Ladino, K. Law, M. Levasseur, Q. Libois, J. Liggio, M. Lizotte, K. M. Macdonald, R. Mahmood, R. V. Martin, R. H. Mason, L. A. Miller, A. Moravek, E. Mortenson, E. L. Mungall, J. G. Murphy, M. Namazi, A.-L. Norman, N. T. O'Neill, J. R. Pierce, L. M. Russell, J. Schneider, H. Schulz, S. Sharma, M. Si, R. M. Staebler, N. S. Steiner, J. L. Thomas, K. von Salzen, J. J. B. Wentzell, M. D. Willis, G. R. Wentworth, J.-W. Xu, J. D. Yakobi-Hancock, Department of Chemistry [University of Toronto], University of Toronto, Environment and Climate Change Canada, School of Engineering [Guelph], University of Guelph, Department of Chemistry [Vancouver] (UBC Chemistry), University of British Columbia (UBC), Département des sciences de la terre et de l'atmosphère [Montréal] (SCTA), Université du Québec à Montréal = University of Québec in Montréal (UQAM), Institut des Sciences de la MER de Rimouski (ISMER), Université du Québec à Rimouski (UQAR), Institute for Atmospheric Physics [Mainz] (IPA), Johannes Gutenberg - Universität Mainz (JGU), Aerosol Physics and Environmental Physics [Vienna], University of Vienna [Vienna], Department of Physics and Atmospheric Science [Halifax], Dalhousie University [Halifax], Department of Chemistry [Lewisburg], Bucknell University, Department of Chemical Engineering and Applied Chemistry (CHEM ENG), Department of Geography and Environmental Management [Waterloo], University of Waterloo [Waterloo], Department of Biology [Québec], Université Laval [Québec] (ULaval), Departement de Biologie [Québec], School of Earth and Ocean Sciences [Victoria] (SEOS), University of Victoria [Canada] (UVIC), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Centre d'Applications et de Recherches en TELédétection [Sherbrooke] (CARTEL), Département de géomatique appliquée [Sherbrooke] (UdeS), Université de Sherbrooke (UdeS)-Université de Sherbrooke (UdeS), Department of Atmospheric Science [Fort Collins], Colorado State University [Fort Collins] (CSU), Particle Chemistry Department [Mainz], Max Planck Institute for Chemistry (MPIC), Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, Centro de Ciencias de la Atmosfera [Mexico], Universidad Nacional Autónoma de México (UNAM), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Air Quality Processes Research Section, Canadian Centre for Climate Modelling and Analysis (CCCma), Institute of Ocean Sciences [Sidney] (IOS), Fisheries and Oceans Canada (DFO), Department of Mathematics [Isfahan], University of Isfahan, Department of Physics and Astronomy [Calgary], University of Calgary, Scripps Institution of Oceanography (SIO), University of California [San Diego] (UC San Diego), University of California-University of California, Institut des Géosciences de l’Environnement (IGE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Recherche pour le Développement (IRD)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Alberta Environment and Parks (AEP), National Research Council of Canada (NRC), Johannes Gutenberg - Universität Mainz = Johannes Gutenberg University (JGU), Universidad Nacional Autónoma de México = National Autonomous University of Mexico (UNAM), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Scripps Institution of Oceanography (SIO - UC San Diego), University of California (UC)-University of California (UC), and Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Arctic haze, Atmospheric Science, 010504 meteorology & atmospheric sciences, Global warming, Climate change, 010501 environmental sciences, Mineral dust, Atmospheric sciences, 01 natural sciences, Sea surface microlayer, lcsh:QC1-999, Atmospheric Sciences, Aerosol, lcsh:Chemistry, Climate Action, Deposition (aerosol physics), lcsh:QD1-999, Arctic, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, 13. Climate action, Meteorology & Atmospheric Sciences, lcsh:Physics, Astronomical and Space Sciences, 0105 earth and related environmental sciences
Abstract

Motivated by the need to predict how the Arctic atmosphere will change in a warming world, this article summarizes recent advances made by the research consortium NETCARE (Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments) that contribute to our fundamental understanding of Arctic aerosol particles as they relate to climate forcing. The overall goal of NETCARE research has been to use an interdisciplinary approach encompassing extensive field observations and a range of chemical transport, earth system, and biogeochemical models. Several major findings and advances have emerged from NETCARE since its formation in 2013. (1) Unexpectedly high summertime dimethyl sulfide (DMS) levels were identified in ocean water (up to 75 nM) and the overlying atmosphere (up to 1 ppbv) in the Canadian Arctic Archipelago (CAA). Furthermore, melt ponds, which are widely prevalent, were identified as an important DMS source (with DMS concentrations of up to 6 nM and a potential contribution to atmospheric DMS of 20 % in the study area). (2) Evidence of widespread particle nucleation and growth in the marine boundary layer was found in the CAA in the summertime, with these events observed on 41 % of days in a 2016 cruise. As well, at Alert, Nunavut, particles that are newly formed and grown under conditions of minimal anthropogenic influence during the months of July and August are estimated to contribute 20 % to 80 % of the 30–50 nm particle number density. DMS-oxidation-driven nucleation is facilitated by the presence of atmospheric ammonia arising from seabird-colony emissions, and potentially also from coastal regions, tundra, and biomass burning. Via accumulation of secondary organic aerosol (SOA), a significant fraction of the new particles grow to sizes that are active in cloud droplet formation. Although the gaseous precursors to Arctic marine SOA remain poorly defined, the measured levels of common continental SOA precursors (isoprene and monoterpenes) were low, whereas elevated mixing ratios of oxygenated volatile organic compounds (OVOCs) were inferred to arise via processes involving the sea surface microlayer. (3) The variability in the vertical distribution of black carbon (BC) under both springtime Arctic haze and more pristine summertime aerosol conditions was observed. Measured particle size distributions and mixing states were used to constrain, for the first time, calculations of aerosol–climate interactions under Arctic conditions. Aircraft- and ground-based measurements were used to better establish the BC source regions that supply the Arctic via long-range transport mechanisms, with evidence for a dominant springtime contribution from eastern and southern Asia to the middle troposphere, and a major contribution from northern Asia to the surface. (4) Measurements of ice nucleating particles (INPs) in the Arctic indicate that a major source of these particles is mineral dust, likely derived from local sources in the summer and long-range transport in the spring. In addition, INPs are abundant in the sea surface microlayer in the Arctic, and possibly play a role in ice nucleation in the atmosphere when mineral dust concentrations are low. (5) Amongst multiple aerosol components, BC was observed to have the smallest effective deposition velocities to high Arctic snow (0.03 cm s−1).

Published
2019
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3. The Water Cycle of the Mid-Holocene West African Monsoon: the Role of Vegetation and Dust Emission Changes

Author

Gabriele Messori, Marco Gaetani, Francesco S. R. Pausata, Qiong Zhang, Qiang Zhang, Bolin Centre for Climate Research, Stockholm University, Department of Meteorology [Stockholm] (MISU), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Department of Physical Geography [Stockholm], Département des sciences de la terre et de l'atmosphère [Montréal] (SCTA), Université du Québec à Montréal = University of Québec in Montréal (UQAM), Agence Nationale de la Recherche, ANR-10-LABX-0018,L-IPSL,LabEx Institut Pierre Simon Laplace (IPSL): Understand climate and anticipate future changes(2010), and Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Atmospheric Science, 010504 meteorology & atmospheric sciences, Orbital forcing, 0207 environmental engineering, 02 engineering and technology, Vegetation, 15. Life on land, Present day, Monsoon, 01 natural sciences, West african, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, Environmental science, Water cycle, 020701 environmental engineering, Holocene, 0105 earth and related environmental sciences, Dust emission
Abstract

International audience; During the mid‐Holocene (6 kyr BP), West Africa experienced a much stronger and geographically extensive monsoon than in the present day. Changes in orbital forcing, vegetation and dust emissions from the Sahara have been identified as key factors driving this intensification. Here, we analyse how the timing, origin and convergence of moisture fluxes contributing to the monsoonal precipitation changes under a range of scenarios: orbital forcing only; orbital and vegetation forcings (Green Sahara); orbital, vegetation and dust forcings (Green Sahara‐reduced dust). We further compare our results to a range of reconstructions of mid‐Holocene precipitation from palaeoclimate archives. The greening of the Sahara leads to a cyclonic water vapour flux anomaly over North Africa with an anomalous westerly flow bringing large amounts of moisture into the Sahel from the Atlantic Ocean. Changes in atmospheric dust under a vegetated Sahara shift the anomalous moisture advection pattern northwards, increasing both moisture convergence and precipitation recycling over the northern Sahel and Sahara and the associated precipitation during the boreal summer. During this season, under both the Green Sahara and Green Sahara‐reduced dust scenarios, local recycling in the Saharan domain exceeds that of the Sahel. This points to local recycling as an important factor modulating vegetation‐precipitation feedbacks and the impact of Saharan dust emissions. Our results also show that temperature and evapotranspiration over the Sahara in the mid‐Holocene are close to Sahelian pre‐industrial values. This suggests that pollen‐based paleoclimate reconstructions of precipitation during the Green Sahara period are likely not biased by possible large evapotranspiration changes in the region.

Published
2019
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4. New insights into aerosol and climate in the Arctic

Author

Abbatt, Jonathan P. D., Leaitch, W. Richard, Aliabadi, Amir A., Bertram, Alan K., Blanchet, Jean-Pierre, Boivin-Rioux, Aude, Bozem, Heiko, Burkart, Julia, Chang, Rachel Y. W., Charette, Joannie, Chaubey, Jai P., Christensen, Robert J., Cirisan, Ana, Collins, Douglas B., Croft, Betty, Dionne, Joelle, Evans, Greg J., Fletcher, Christopher G., Ghahremaninezhad, Roghayeh, Girard, Eric, Gong, Wanmin, Gosselin, Michel, Gourdal, Margaux, Hanna, Sarah J., Hayashida, Hakase, Herber, Andreas B., Hesaraki, Sareh, Hoor, Peter, Huang, Lin, Hussherr, Rachel, Irish, Victoria E., Keita, Setigui A., Kodros, John K., Köllner, Franziska, Kolonjari, Felicia, Kunkel, Daniel, Ladino, Luis A., Law, Kathy S., Levasseur, Maurice, Libois, Quentin, Liggio, John, Lizotte, Martine, Macdonald, Katrina M., Mahmood, Rashed, Martin, Randall V., Mason, Ryan H., Miller, Lisa A., Moravek, Alexander, Mortenson, Eric, Mungall, Emma L., Murphy, Jennifer G., Namazi, Maryam, Norman, Ann-Lise, O'Neill, Norman T., Pierce, Jeffrey R., Russell, Lynn M., Schneider, Johannes, Schulz, Hannes, Sharma, Sangeeta, Si, Meng, Staebler, Ralf M., Steiner, Nadja S., Gali, Marti, Thomas, Jennie L., von Salzen, Knut, Wentzell, Jeremy J. B., Willis, Megan D., Wentworth, Gregory R., Xu, Jun-Wei, Yakobi-Hancock, Jacqueline D., Department of Chemistry [University of Toronto], University of Toronto, Environment and Climate Change Canada, School of Engineering [Guelph], University of Guelph, Department of Chemistry [Vancouver] (UBC Chemistry), University of British Columbia (UBC), Département des sciences de la terre et de l'atmosphère [Montréal] (SCTA), Université du Québec à Montréal = University of Québec in Montréal (UQAM), Institut des Sciences de la MER de Rimouski (ISMER), Université du Québec à Rimouski (UQAR), Institute for Atmospheric Physics [Mainz] (IPA), Johannes Gutenberg - Universität Mainz (JGU), Aerosol Physics and Environmental Physics [Vienna], University of Vienna [Vienna], Department of Physics and Atmospheric Science [Halifax], Dalhousie University [Halifax], Department of Chemistry [Lewisburg], Bucknell University, Department of Chemical Engineering and Applied Chemistry (CHEM ENG), Department of Geography and Environmental Management [Waterloo], University of Waterloo [Waterloo], Departement de Biologie [Québec], Université Laval [Québec] (ULaval), School of Earth and Ocean Sciences [Victoria] (SEOS), University of Victoria [Canada] (UVIC), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Centre d'Applications et de Recherches en TELédétection (CARTEL), Université de Sherbrooke [Sherbrooke], Department of Atmospheric Science [Fort Collins], Colorado State University [Fort Collins] (CSU), Particle Chemistry Department [Mainz], Max Planck Institute for Chemistry (MPIC), Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, Centro de Ciencias de la Atmosfera [Mexico], Universidad Nacional Autónoma de México (UNAM), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Department of Biology [Québec], Air Quality Processes Research Section, Canadian Centre for Climate Modelling and Analysis (CCCma), Institute of Ocean Sciences [Sidney] (IOS), Fisheries and Oceans Canada (DFO), Department of Mathematics [Isfahan], University of Isfahan, Department of Physics and Astronomy [Calgary], University of Calgary, Scripps Institution of Oceanography (SIO), University of California [San Diego] (UC San Diego), University of California-University of California, Lawrence Berkeley National Laboratory [Berkeley] (LBNL), and National Research Council of Canada (NRC)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology
Abstract

International audience; Motivated by the need to predict how the Arctic atmosphere will change in a warming world, this article summarizes recent advances made by the research consortium NETCARE (Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments) that contribute to our fundamental understanding of Arctic aerosol particles as they relate to climate forcing. The overall goal of NETCARE research has been to use an interdisciplinary approach encompassing extensive field observations and a range of chemical transport, earth system, and biogeochemical models. Several major findings and advances have emerged from NETCARE since its formation in 2013 . (1) Unexpectedly high summertime dimethyl sulfide (DMS) levels were identified in ocean water and the overlying atmosphere in the Canadian Arctic Archipelago (CAA). Furthermore, melt ponds, which are widely prevalent, were identified as an important DMS source. (2) Evidence was found of widespread particle nucleation and growth in the marine boundary layer in the CAA in the summertime. DMS-oxidation-driven nucleation is facilitated by the presence of atmospheric ammonia arising from sea bird colony emissions, and potentially also from coastal regions, tundra, and biomass burning. Via accumulation of secondary organic material (SOA), a significant fraction of the new particles grow to sizes that are active in cloud droplet formation. Although the gaseous precursors to Arctic marine SOA remain poorly defined, the measured levels of common continental SOA precursors (isoprene and monoterpenes) were low, whereas elevated mixing ratios of oxygenated volatile organic compounds were inferred to arise via processes involving the sea surface microlayer. (3) The variability in the vertical distribution of black carbon (BC) under both springtime Arctic haze and more pristine summertime aerosol conditions was observed. Measured particle size distributions and mixing states were used to constrain, for the first time, calculations of aerosol–climate interactions under Arctic conditions. Aircraft- and ground-based measurements were used to better establish the BC source regions that supply the Arctic via long-range transport mechanisms. (4) Measurements of ice nucleating particles (INPs) in the Arctic indicate that a major source of these particles is mineral dust, likely derived from local sources in the summer and long-range transport in the spring. In addition, INPs are abundant in the sea surface microlayer in the Arctic, and possibly play a role in ice nucleation in the atmosphere when mineral dust concentrations are low. (5) Amongst multiple aerosol components, BC was observed to have the smallest effective deposition velocities to high Arctic snow.

Published
2018

5. Understanding the mechanisms behind the northward extension of the West African Monsoon during the Mid-Holocene

Author

Marco Gaetani, Qiong Zhang, Cyrille Flamant, Francesco S. R. Pausata, Gabriele Messori, TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Bolin Centre for Climate Research, Stockholm University, Department of Meteorology [Stockholm] (MISU), Department of Physical Geography [Stockholm], Département des sciences de la terre et de l'atmosphère [Montréal] (SCTA), Université du Québec à Montréal = University of Québec in Montréal (UQAM), Agence Nationale de la Recherche (ANR), Swedish Research Council (MILEX project), and ANR-10-LABX-0018,L-IPSL,LabEx Institut Pierre Simon Laplace (IPSL): Understand climate and anticipate future changes(2010)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Atmospheric Science, 010504 meteorology & atmospheric sciences, Orbital forcing, Atmospheric circulation, Tropical wave, 15. Life on land, Radiative forcing, 010502 geochemistry & geophysics, Atmospheric sciences, Monsoon, 01 natural sciences, African easterly jet, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, Paleoclimatology, Environmental science, Holocene, 0105 earth and related environmental sciences
Abstract

Understanding the West African monsoon (WAM) dynamics in the mid-Holocene (MH) is a crucial issue in climate modeling, because numerical models typically fail to reproduce the extensive precipitation suggested by proxy evidence. This discrepancy may be largely due to the assumption of both unrealistic land surface cover and atmospheric aerosol concentration. In this study, the MH environment is simulated in numerical experiments by imposing extensive vegetation over the Sahara and the consequent reduction in airborne dust concentration. A dramatic increase in precipitation is simulated across the whole of West Africa, up to the Mediterranean coast. This precipitation response is in better agreement with proxy data, in comparison with the case in which only changes in orbital forcing are considered. Results show a substantial modification of the monsoonal circulation, characterized by an intensification of large-scale deep convection through the entire Sahara, and a weakening and northward shift (~6.5°) of the African easterly jet. The greening of the Sahara also leads to a substantial reduction in the African easterly wave activity and associated precipitation. The reorganization of the regional atmospheric circulation is driven by the vegetation effect on radiative forcing and associated heat fluxes, with the reduction in dust concentration to enhance this response. The results for the WAM in the MH present important implications for understanding future climate scenarios in the region and in teleconnected areas, in the context of projected wetter conditions in West Africa.

Published
2017
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6. Indian monsoon variations during three contrasting climatic periods: The Holocene, Heinrich Stadial 2 and the last interglacial–glacial transition

Author

Coralie Zorzi, Liviu Giosan, Srinivasan Prasad, Vincent Hanquiez, Maria Fernanda Sanchez Goñi, Krishnamurthy Anupama, Joel E. Johnson, Département des sciences de la terre et de l'atmosphère [Montréal] (SCTA), Université du Québec à Montréal = University of Québec in Montréal (UQAM), École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL), Institut Français de Pondichéry (IFP), Ministère de l'Europe et des Affaires étrangères (MEAE)-Centre National de la Recherche Scientifique (CNRS), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), University of New Hampshire (UNH), Department of Geology and Geophysics, and Woods Hole Oceanographic Institution (WHOI)

Subjects
Monsoon of South Asia, Climatology, 010506 paleontology, Archeology, Global and Planetary Change, geography, geography.geographical_feature_category, Indian monsoon, 010504 meteorology & atmospheric sciences, Geology, 15. Life on land, Monsoon, 01 natural sciences, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Interglacial, East Asian Monsoon, Glacial period, Stadial, Ice sheet, Ecology, Evolution, Behavior and Systematics, Holocene, 0105 earth and related environmental sciences
Abstract

International audience; In contrast to the East Asian and African monsoons the Indian monsoon is still poorly documented throughout the last climatic cycle (last 135,000 years). Pollen analysis from two marine sediment cores (NGHP-01-16A and NGHP-01-19B) collected from the offshore Godavari and Mahanadi basins, both located in the Core Monsoon Zone (CMZ) reveals changes in Indian summer monsoon variability and intensity during three contrasting climatic periods: the Holocene, the Heinrich Stadial (HS) 2 and the Marine Isotopic Stage (MIS) 5/4 during the ice sheet growth transition. During the first part of the Holocene between 11,300 and 4200 cal years BP, characterized by high insolation (minimum precession, maximum obliquity), the maximum extension of the coastal forest and mangrove reflects high monsoon rainfall. This climatic regime contrasts with that of the second phase of the Holocene, from 4200 cal years BP to the present, marked by the development of drier vegetation in a context of low insolation (maximum precession, minimum obliquity). The historical period in India is characterized by an alternation of strong and weak monsoon centennial phases that may reflect the Medieval Climate Anomaly and the Little Ice Age, respectively. During the HS 2, a period of low insolation and extensive iceberg discharge in the North Atlantic Ocean, vegetation was dominated by grassland and dry flora indicating pronounced aridity as the result of a weak Indian summer monsoon. The MIS 5/4 glaciation, also associated with low insolation but moderate freshwater fluxes, was characterized by a weaker reduction of the Indian summer monsoon and a decrease of seasonal contrast as recorded by the expansion of dry vegetation and the development of Artemisia, respectively. Our results support model predictions suggesting that insolation changes control the long term trend of the Indian monsoon precipitation, but its millennial scale variability and intensity are instead modulated by atmospheric teleconnections to remote phenomena in the North Atlantic, Eurasia or the Indian Ocean.

Published
2015
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