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1. Bio-physicochemistry of tropical clouds at Maïdo (Réunion Island, Indian Ocean): overview of results from the BIO-MAÏDO campaign

Author

Leriche, Maud, Tulet, Pierre, Deguillaume, Laurent, Burnet, Frédéric, Colomb, Aurélie, Borbon, Agnès, Jambert, Corinne, Duflot, Valentin, Houdier, Stéphan, Jaffrezo, Jean-Luc, Vaïtilingom, Mickaël, Mouchel-Vallon, Camille, Dominutti, Pamela, Rocco, Manon, Gdachi, Samira, Brissy, Maxence, Fathalli, Maroua, Maury, Nicolas, Verreyken, Bert, Amelynck, Crist, Schoon, Niels, Gros, Valérie, Pichon, Jean-Marc, Ribeiro, Mickael, Pique, Eric, Leclerc, Emmanuel, Bourrianne, Thierry, Roy, Axel, Moulin, Eric, Barrie, Joël, Metzger, Jean-Marc, Péris, Guillaume, Guadagno, Christian, Bhugwant, Chatrapatty, Tibere, Jean-Mathieu, Tournigand, Arnaud, Freney, Evelyn, Sellegri, Karine, Delort, Anne-Marie, Amato, Pierre, Joly, Muriel, Baray, Jean-Luc, Renard, Pascal, Bianco, Angelica, Réchou, Anne, Payen, Guillaume, Laboratoire de Météorologie Physique (LaMP), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Centre ESCER, Université du Québec à Montréal = University of Québec in Montréal (UQAM), Laboratoire d'aérologie (LAERO), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire de l'Atmosphère et des Cyclones (LACy), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Météo-France, Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Laboratoire de Recherche en Géosciences et Energies [UR2_1] (LARGE), Université des Antilles (UA), Institut de Chimie de Clermont-Ferrand (ICCF), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national polytechnique Clermont Auvergne (INP Clermont Auvergne), Université Clermont Auvergne (UCA)-Université Clermont Auvergne (UCA), Department of Chemistry, University of Ghent, Ghent, Belgium, Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Departement of Chemistry, University of Ghent, 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), Observatoire des Sciences de l'Univers de La Réunion (OSU-Réunion), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR), ATMO-Réunion, ANR, BIO-MAÏDO, OCTAVE, European Project: 654109,H2020,H2020-INFRAIA-2014-2015,ACTRIS-2(2015), and ANR-18-CE01-0013,BIO-MAIDO,Bio-physicochimie des nuages tropicaux au Maïdo (Île de la Réunion) : processus et impacts sur la formation des aérosols organiques secondaires(2018)

Subjects
Atmospheric chemistry, Field campaign, tropical atmosphere, [SDU]Sciences of the Universe [physics], COV, Réunion Island, cloud, aerosols
Abstract

The BIO-MAÏDO (Bio-physicochemistry of tropical clouds at Maïdo (Réunion Island): processes and impacts on secondary organic aerosols formation) campaign was conducted from the 13th of March to the 4th of April 2019 on the tropical Réunion Island and implied several scientific teams and state-of-the-art instrumentation. The campaign was part of the BIO-MAÏDO project with the main objective is to improve our understanding of cloud impacts on the formation of secondary organic aerosols (SOA) from biogenic volatile organic compounds (BVOC) precursors in a tropical environment. Instruments were deployed at five sites: a receptor site, the Maïdo observatory (MO) at 2165 m asl, and four sites along the slope of the Maïdo mountain. The obtained dataset includes measurements of the gas-phase mixings ratio of volatile organic compounds (VOC), the characterization of the physical, chemical, and biological (bacterial diversity) properties of aerosols and the characterization of the physical, chemical and biological (identification of viable bacteria through culture-based approaches) properties of the cloud water. In addition, the turbulent parameters of the boundary layer, radiative fluxes, and emissions fluxes of BVOC from the surrounding vegetation were measured to help with the interpretation of the observed chemical concentrations in the different phases. Dynamical analyses using back-trajectories show two preferred trajectories routes for air masses arriving at MO during the daytime both corresponding to the return branches of the trade winds associated with the up-slopes thermal breezes, and both influenced by marine boundary layer and endemic forest below the Maïdo observatory. Additional analysis based on a high-resolution Meso-NH simulation for a typical cloudy day indicates that air masses sampled at MO likely encountered cloud processing during its transport along the slope. The highest mixing ratio of oxygenated VOC (OVOC) were measured above the site located in the endemic forest and the highest contribution of OVOC to total VOC at MO. Chemical composition of particles during the daytime shows that organic aerosol is more oxidized at MO than at other sites along the slope. This is a signature of photochemical aerosols aging along the slope. A higher concentration of oxalic acid at a site below MO indicates this oxidation occurs potentially through cloud processing. Despite an in-depth analysis of organic compounds in cloud water, around 80% on average of dissolved organic compounds is undefined highlighting the complexity of the cloud organic matter. The BIO-MAÏDO project is focusing on the analysis of observations and processes using numerical simulations: a 0D cloud chemistry model including biodegradation by bacteria in cloud water and a high-resolution 3D model coupling dynamical, microphysical and chemical processes.

Published
2023

2. Evaluation of the Sources, Precursors, and Processing of Aerosols at a High-Altitude Tropical Site

Author

Dominutti, Pamela, Chevassus, Emmanuel, Baray, Jean-Luc, Jaffrezo, Jean-Luc, Borbon, Agnès, Colomb, Aurélie, Deguillaume, Laurent, El Gdachi, Samira, Houdier, Stephan, Leriche, Maud, Metzger, Jean-Marc, Rocco, Manon, Tulet, Pierre, Sellegri, Karine, Freney, Evelyn, Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Laboratoire de Météorologie Physique (LaMP), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Laboratoire d'aérologie (LAERO), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire de l'Atmosphère et des Cyclones (LACy), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Météo-France, Centre ESCER, Université du Québec à Montréal = University of Québec in Montréal (UQAM), Observatoire des Sciences de l'Univers de La Réunion (OSU-Réunion), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR), ANR-18-CE01-0013,BIO-MAIDO,Bio-physicochimie des nuages tropicaux au Maïdo (Île de la Réunion) : processus et impacts sur la formation des aérosols organiques secondaires(2018), and European Project: 654109,H2020,H2020-INFRAIA-2014-2015,ACTRIS-2(2015)

Subjects
Atmospheric Science, Cloud processing, Positive matrix factorization, Space and Planetary Science, Geochemistry and Petrology, ToF-ACSM, [SDE.IE]Environmental Sciences/Environmental Engineering, [CHIM.ANAL]Chemical Sciences/Analytical chemistry, [SDE.MCG]Environmental Sciences/Global Changes, Secondary organic aerosols, Aqueous-phase chemistry, Southern Hemisphere, [SDE.ES]Environmental Sciences/Environmental and Society
Abstract

International audience; This work presents the results from a set of aerosol- and gas-phase measurements collected during the BIO-MAIDÖ field campaign in Reunion ́ between March 8 and April 5, 2019. Several offline and online sampling devices were installed at the Maidö Observatory (MO), a remote high-altitude site in the Southern Hemisphere, allowing the physical and chemical characterization of atmospheric aerosols and gases. The evaluation of short-lived gas-phase measurements allows us to conclude that air masses sampled during this period contained little or no anthropogenic influence. The dominance of sulfate and organic species in the submicron fraction of the aerosol is similar to that measured at other coastal sites.Carboxylic acids on PM10 showed a significant contribution of oxalic acid, a typical tracer of aqueous processed air masses, increasing at the end of the campaign. This result agrees with the positive matrix factorization analysis of the submicron organic aerosol, where more oxidized organic aerosols (MOOAs) dominated the organic aerosol with an increasing contribution toward the end of the campaign. Using a combination of air mass trajectories (model predictions), it was possible to assess the impact of aqueous phase processing on the formation of secondary organic aerosols(SOAs). Our results show how specific chemical signatures and physical properties of air masses, possibly affected by cloud processing, can be identified at Reunion. ́ These changes in properties are represented by a shift in aerosol size distribution to large diameters and an increased contribution of secondary sulfate and organic aerosols after cloud processing.

Published
2022
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3. High Resolution Dynamical Analysis of Volatile Organic Compounds (VOC) Measurements During the BIO‐MAÏDO Field Campaign (Réunion Island, Indian Ocean)

Author

M. Rocco, J.‐L. Baray, A. Colomb, A. Borbon, P. Dominutti, P. Tulet, C. Amelynck, N. Schoon, B. Verreyken, V. Duflot, V. Gros, R. Sarda‐Estève, G. Péris, C. Guadagno, M. Leriche, Laboratoire de Météorologie Physique (LaMP), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Laboratoire de l'Atmosphère et des Cyclones (LACy), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Météo-France, Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Laboratoire d'aérologie (LAERO), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Universiteit Gent = Ghent University (UGENT), NOAA Chemical Sciences Laboratory (CSL), National Oceanic and Atmospheric Administration (NOAA), 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), Chimie Atmosphérique Expérimentale (CAE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Centre ESCER, Université du Québec à Montréal = University of Québec in Montréal (UQAM), ANR-18-CE01-0013,BIO-MAIDO,Bio-physicochimie des nuages tropicaux au Maïdo (Île de la Réunion) : processus et impacts sur la formation des aérosols organiques secondaires(2018), and European Project: 654109,H2020,H2020-INFRAIA-2014-2015,ACTRIS-2(2015)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, BIOMASS BURNING PLUMES, 55-DEGREES E, AEROSOL, BOUNDARY-LAYER, OXIDATION, Chemistry, Geophysics, 21-DEGREES S, Space and Planetary Science, DEPENDENCE, ISOPRENE, Earth and Planetary Sciences (miscellaneous), [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ATMOSPHERIC CHEMISTRY, SYSTEM
Abstract

This study presents a high-resolution dynamical analysis of Volatile Organic Compound (VOC) concentrations measured from March 11 to April 4 2019 at Reunion Island during the BIO-MAIDO (Bio-physicochemistry of tropical clouds at Maido: processes and impacts on secondary organic aerosols formation) campaign. We detail the dynamical and chemical processes that govern atmospheric VOC concentrations at two targeted sites of the western slope of Reunion Island: Petite France (PF), 950 m above sea level (a.s.l.) and Maido Observatory (MO), 2150 m a.s.l. A dynamical connection between PF and MO is found during four selected days: March 28 and 31, April 1 and 3. Trajectory calculations using the coupling of Meso-Computing Advection-interpolation of atmospheric parameters and Trajectory tool (CAT) (100 m horizontal resolution of Meso-NH high-resolution non-hydrostatic model and the CAT trajectory model) Lagrangian transport model showed that air masses were dynamically linked between the two measurements sites for 19% of the time during the complete campaign. Trajectories from the Meso-CAT model combined with the Corine Land Cover-2018 register shows that backward-trajectories are frequently located above biogenic area (mixed forest, 3%-46% of total number trajectory point) and cultures area (e.g., sugar cane plantation, 1%-17%). Regarding VOCs concentrations, air masses coming from downhill MO are associated with significant measured concentrations of isoprene, isoprene oxidation products and benzene. Averaged concentration daytime ratios of isoprene and isoprene oxidation products from PF to MO are 0.73 +/- 1.01 and 0.26 +/- 0.26 respectively illustrating a loss of these VOCs due to deposition, oxidation, or possibility dilution on clouds.

Published
2022
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4. Comparison of TOA and BOA LW Radiation Fluxes Inferred From Ground‐Based Sensors, A‐Train Satellite Observations and ERA Reanalyzes at the High Arctic Station Eureka Over the 2002–2020 Period

Author

Jacques Pelon, Christopher J. Cox, Edwin W. Eloranta, Julien Delanoë, Yann Blanchard, Taniel Uttal, Centre ESCER, Université du Québec à Montréal = University of Québec in Montréal (UQAM), 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), Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado [Boulder]-National Oceanic and Atmospheric Administration (NOAA), National Oceanic and Atmospheric Administration (NOAA), SPACE - LATMOS, Space Science and Engineering Center [Madison] (SSEC), and University of Wisconsin-Madison

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Opacity, clouds, 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, intercomparison, Atmosphere, Flux (metallurgy), Earth and Planetary Sciences (miscellaneous), Radiative transfer, high Arctic, satellite data, 0105 earth and related environmental sciences, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Attenuation, re-analyses, radiation, Geophysics, Lidar, Arctic, 13. Climate action, Space and Planetary Science, Environmental science, Satellite
Abstract

International audience; This study focuses on the accuracy of longwave radiation flux retrievals at the top and bottom of the atmosphere at Eureka station, Canada, in the high Arctic. We report comparisons between seven products derived from (a) calculations based on a combination of ground-based and space-based lidar and radar observations, (b) standard radiometric observations from the CERES sensor, (c) direct observations at the surface from a broadband radiation station, and (d) the ERA-Interim and ERA5 reanalyzes. Statistical, independent analyses are first performed to look at recurring bias and trends in fluxes at Top and Bottom of the Atmosphere (TOA, BOA). The analysis is further refined by comparing fluxes derived from coincident observations decomposed by scene types. Results show that radiative transfer calculations using ground-based lidar-radar profiles derived at Eureka agree well with TOA LW fluxes observed by CERES and with BOA LW fluxes reference. CloudSat-CALIPSO also shows good agreement with calculations from ground-based sensor observations, with a relatively small bias. This bias is shown to be largely due to low and thick cloud occurrences that the satellites are insensitive to owing to attenuation from clouds above and surface clutter. These conditions of opaque low clouds, cause an even more pronounced bias for CERES BOA flux calculation in winter, due to the deficit of low clouds identified by MODIS. ERA-I and ERA5 fluxes behave differently, the large positive bias observed with ERA-I is much reduced in ERA5. ERA5 is closer to reference observations due to better behavior of low and mid-level clouds and surface temperature.

Published
2021
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5. Toward a Better Surface Radiation Budget Analysis Over Sea Ice in the High Arctic Ocean: A Comparative Study Between Satellite, Reanalysis, and local‐scale Observations

Author

Stephen R. Hudson, Mats A. Granskog, Lilian Loyer, C. Di Biagio, Yann Blanchard, Jacques Pelon, Jean-Christophe Raut, Vincent Mariage, Von P. Walden, Seiji Kato, 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), Centre ESCER, Université du Québec à Montréal = University of Québec in Montréal (UQAM), Norwegian Polar Institute, Department of Civil and Environmental Engineering [Pullman], Washington State University (WSU), NASA Langley Research Center [Hampton] (LaRC), and ANR-10-EQPX-0013,PLANAQUA,PLAteforme expérimentale NAtionale d'écologie aQUAtique(2010)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Longwave, Albedo, 010502 geochemistry & geophysics, 01 natural sciences, Geophysics, Lidar, Arctic, 13. Climate action, Space and Planetary Science, Downwelling, Climatology, Earth and Planetary Sciences (miscellaneous), Sea ice, Environmental science, Satellite, 14. Life underwater, Shortwave, 0105 earth and related environmental sciences
Abstract

International audience; Reanalysis datasets from atmospheric models and satellite products are often used for Arctic surface shortwave (SW) and longwave (LW) radiative budget analyses, but they suffer from limitations and require validation against local‒scale observations. These are rare in the high Arctic, especially for longer periods that include seasonal transitions. In this study, radiation and meteorological observations acquired during the Norwegian Young Sea Ice Cruise (N‒ICE2015) campaign over sea ice north of Svalbard (80‒83°N, 5‒25°E) from January to June 2015, cloud lidar observations from the Ice‒Atmosphere‒Ocean Observing System (IAOOS) and the Cloud and Aerosol Lidar with Orthogonal Polarization (CALIOP) are compared to daily and monthly satellite retrievals from the Clouds and the Earth's Radiant Energy System (CERES) and ERA‒Interim and ERA5 reanalyses. Results indicate that surface temperature is a significant driver for winter LW radiation biases in both satellite and reanalysis data, along with cloud optical depth in CERES. In May the SW and LW downwelling irradiances are close to observations and cloud properties are well captured (except for ERA‐Interim), while SW upward irradiances are biased low due to surface albedo biases in all datasets. Net SW and LW radiation biases are comparable (⁓20‒30 Wm‒2) but opposite in sign for ERA‒Interim and CERES in May, which allows for error compensation. Biases reduce to ±10 Wm‒2 in ERA5. In June downward LW remains biased low (8‒10 Wm‒2) in all datasets suggesting unsettled cloud representation issues. Surface albedo always differs by more than 0.1 between datasets, leading to significant SW and total flux differences.

Published
2021
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6. Optimal configuration of a far-infrared radiometer to the study the Arctic winter atmosphere

Author

Quentin Libois, Pierre Gauthier, Jean-Pierre Blanchet, Laurence Coursol, Centre ESCER, Université du Québec à Montréal = University of Québec in Montréal (UQAM), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, Radiometer, 010504 meteorology & atmospheric sciences, Polar night, Humidity, Context (language use), [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology, 7. Clean energy, 01 natural sciences, Atmosphere, Geophysics, Far infrared, 13. Climate action, Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), Environmental science, Satellite, Water vapor, 0105 earth and related environmental sciences, Remote sensing
Abstract

International audience; Several FIR satellite missions are planned for the next decade, with a special interest for the Arctic region. A theoretical study is performed to help about the design of a FIR radiometer, whose configuration in terms of channels number and frequencies is optimized based on information content analysis. The problem is cast in a context of vertical column experiments (1D) to determine the optimal configuration of a FIR radiometer to study the Arctic polar night. If only observations of the FIR radiometer were assimilated, the results show that for humidity, 90 % of the total information content is obtained with 4 bands whereas for temperature 10 bands are needed. When the FIR measurements are assimilated on top of those from the Advanced Infrared Sounder (AIRS), the former bring in additional information between the surface and 850 hPa and from 550 hPa to 250 hPa for humidity. Moreover, between 400 hPa and 200 hPa, the FIR radiometer is better than AIRS at reducing the analysis error variance for humidity. This indicates the potential of FIR observations for improving water vapor analysis in the Arctic.

Published
2020
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7. A new parameterization of ice heterogeneous nucleation coupled to aerosol chemistry in WRF-Chem model version 3.5.1: evaluation through the ISDAC measurements

Author

Setigui Aboubacar Keita, Eric Girard, Jean-Christophe Raut, Maud Leriche, Jean-Pierre Blanchet, Jacques Pelon, Tatsuo Onishi, Ana Cirisan, Centre ESCER, Université du Québec à Montréal = University of Québec in Montréal (UQAM), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'aérologie (LAERO), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), 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)-Université Fédérale Toulouse Midi-Pyrénées-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), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 010504 meteorology & atmospheric sciences, 13. Climate action, 010501 environmental sciences, 01 natural sciences, 0105 earth and related environmental sciences
Abstract

In the Arctic, during polar night and early spring, ice clouds are separated into two leading types: (1) TIC1 clouds characterized by large concentration of very small crystals, and TIC2 clouds characterized by low concentration of large ice crystals. Using suitable parameterization of heterogeneous ice nucleation is essential for properly representing ice cloud in meteorological and climate model and subsequently understanding their interactions with aerosols and radiation. Here, we describe a new parameterization for ice crystals formation by heterogeneous nucleation coupled to aerosols chemistry in WRF-Chem. The parameterization is implemented in the Milbrandt and Yau’s two-moment cloud microphysics scheme and we assess how the WRF-Chem model responds to the real time interaction between chemistry and the new parameterization. Well-documented reference cases provided us in situ data from the spring 2008 Indirect and Semi-Direct Aerosol Campaign (ISDAC) campaign over Alaska. Our analysis reveals that the new parameterization clearly improves the representation of the IWC in polluted or unpolluted air masses and shows the poor performance of the reference parameterization in representing ice clouds with low IWC. The new parameterization is, thus able to represent TIC1 and TIC2 microphysical characteristics at the top of the clouds were heterogeneous ice nucleation is most likely occurring even knowing the bias of simulated aerosols by WRF-Chem over Arctic.

Published
2020

8. A new parameterization of ice heterogeneous nucleation coupled to aerosol chemistry in WRF-Chem model version 3.5.1: evaluation through ISDAC measurements

Author

S. A. Keita, E. Girard, J.-C. Raut, M. Leriche, J.-P. Blanchet, J. Pelon, T. Onishi, A. Cirisan, Centre ESCER, Université du Québec à Montréal = University of Québec in Montréal (UQAM), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'aérologie (LAERO), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Physique (LaMP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), 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), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, and 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)-Université Fédérale Toulouse Midi-Pyrénées-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Ice cloud, 010504 meteorology & atmospheric sciences, Ice crystals, lcsh:QE1-996.5, Nucleation, 010501 environmental sciences, Atmospheric sciences, 01 natural sciences, Aerosol, lcsh:Geology, Arctic, 13. Climate action, Weather Research and Forecasting Model, Ice nucleus, Climate model, 0105 earth and related environmental sciences
Abstract

In the Arctic, during polar night and early spring, ice clouds are separated into two leading types of ice clouds (TICs): (1) TIC1 clouds characterized by a large concentration of very small crystals and TIC2 clouds characterized by a low concentration of large ice crystals. Using a suitable parameterization of heterogeneous ice nucleation is essential for properly representing ice clouds in meteorological and climate models and subsequently understanding their interactions with aerosols and radiation. Here, we describe a new parameterization for ice crystal formation by heterogeneous nucleation in water-subsaturated conditions coupled to aerosol chemistry in the Weather Research and Forecasting model coupled with chemistry (WRF-Chem). The parameterization is implemented in the Milbrandt and Yau (2005a, b) two-moment cloud microphysics scheme, and we assess how the WRF-Chem model responds to the run-time interaction between chemistry and the new parameterization. Well-documented reference cases provided us with in situ data from the spring 2008 Indirect and Semi-Direct Aerosol Campaign (ISDAC) over Alaska. Our analysis reveals that the new parameterization clearly improves the representation of the ice water content (IWC) in polluted or unpolluted air masses and shows the poor performance of the reference parameterization in representing ice clouds with low IWC. The new parameterization is able to represent TIC1 and TIC2 microphysical characteristics at the top of the clouds, where heterogenous ice nucleation is most likely occurring, even with the known bias of simulated aerosols by WRF-Chem over the Arctic.

Published
2020
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9. Airborne observations of far-infrared upwelling radiance in the Arctic

Author

Amir A. Aliabadi, Jean-Pierre Blanchet, W. Richard Leaitch, Heiko Bozem, Julia Burkart, Quentin Libois, Liviu Ivanescu, Andreas Herber, Eric Girard, Hannes Schulz, Jonathan P. D. Abbatt, Centre ESCER, Université du Québec à Montréal = University of Québec in Montréal (UQAM), Alfred Wegener Institute for Polar and Marine Research (AWI), Institute for Atmospheric Physics [Mainz] (IPA), Johannes Gutenberg - Universität Mainz (JGU), Environment and Climate Change Canada, Department of Chemistry [University of Toronto], University of Toronto, and University of Guelph

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Atmospheric Science, Radiometer, 010504 meteorology & atmospheric sciences, media_common.quotation_subject, Atmospheric sciences, 01 natural sciences, lcsh:QC1-999, lcsh:Chemistry, 010309 optics, Atmosphere, lcsh:QD1-999, Arctic, 13. Climate action, Sky, 0103 physical sciences, Radiance, Radiative transfer, Environmental science, Radiometry, lcsh:Physics, Water vapor, 0105 earth and related environmental sciences, media_common, Remote sensing
Abstract

The first airborne measurements of the Far-InfraRed Radiometer (FIRR) were performed in April 2015 during the panarctic NETCARE campaign. Vertical profiles of spectral upwelling radiance in the range 8–50 μm were measured in clear and cloudy conditions from the surface up to 6 km. The clear-sky profiles highlight the strong dependence of radiative fluxes to the temperature inversion typical of the Arctic. Measurements acquired for total column water vapor from 1.5 to 10.5 mm also underline the sensitivity of the far-infrared greenhouse effect to specific humidity. The cloudy cases show that optically thin ice clouds increase the cooling rate of the atmosphere by a factor up to three, making them important pieces of the Arctic energy balance. One such cloud exhibited a very complex spatial structure, characterized by large horizontal heterogeneities at the kilometre-scale. This emphasizes the difficulty to obtain representative cloud observations with airborne measurements, but also points out how challenging it is to model polar clouds radiative effects. These radiance measurements were successfully compared to simulations, suggesting that state-of-the-art radiative transfer models are suited to study the cold and dry Arctic atmosphere. Although FIRR in situ performances compare well to its laboratory performances, complementary simulations show that upgrading the FIRR radiometric resolution would greatly increase its sensitivity to atmospheric and cloud properties. Improved instrument temperature stability in flight and expected technological progress should help meet this objective. The campaign overall highlights the potential for airborne far-infrared radiometry and constitutes a relevant reference for future similar studies dedicated to the Arctic, and for the development of spaceborne instruments.

Published
2016
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10. A microbolometer-based far infrared radiometer to study thin ice clouds in the Arctic

Author

Laurence Coursol, L. S Pelletier, Jean-Pierre Blanchet, Quentin Libois, Francesco Barbero, Yacine Bouzid, Eric Girard, Christian Proulx, Liviu Ivanescu, Centre ESCER, and Université du Québec à Montréal = University of Québec in Montréal (UQAM)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, 01 natural sciences, 010309 optics, Optics, Far infrared, 0103 physical sciences, Radiative transfer, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], lcsh:TA170-171, 0105 earth and related environmental sciences, Remote sensing, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Ice cloud, Radiometer, lcsh:TA715-787, business.industry, lcsh:Earthwork. Foundations, Microbolometer, Spectral bands, lcsh:Environmental engineering, 13. Climate action, Radiance, Environmental science, business, Water vapor
Abstract

A far infrared radiometer (FIRR) dedicated to measuring radiation emitted by clear and cloudy atmospheres was developed in the framework of the Thin Ice Clouds in Far InfraRed Experiment (TICFIRE) technology demonstration satellite project. The FIRR detector is an array of 80 × 60 uncooled microbolometers coated with gold black to enhance the absorptivity and responsivity. A filter wheel is used to select atmospheric radiation in nine spectral bands ranging from 8 to 50 µm. Calibrated radiances are obtained using two well-calibrated blackbodies. Images are acquired at a frame rate of 120 Hz, and temporally averaged to reduce electronic noise. A complete measurement sequence takes about 120 s. With a field of view of 6°, the FIRR is not intended to be an imager. Hence spatial average is computed over 193 illuminated pixels to increase the signal-to-noise ratio and consequently the detector resolution. This results in an improvement by a factor of 5 compared to individual pixel measurements. Another threefold increase in resolution is obtained using 193 non-illuminated pixels to remove correlated electronic noise, leading an overall resolution of approximately 0.015 W m−2 sr−1. Laboratory measurements performed on well-known targets suggest an absolute accuracy close to 0.02 W m−2 sr−1, which ensures atmospheric radiance is retrieved with an accuracy better than 1 %. Preliminary in situ experiments performed from the ground in winter and in summer on clear and cloudy atmospheres are compared to radiative transfer simulations. They point out the FIRR ability to detect clouds and changes in relative humidity of a few percent in various atmospheric conditions, paving the way for the development of new algorithms dedicated to ice cloud characterization and water vapor retrieval.

Published
2018
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11. Simulating Arctic Ice Clouds during Spring Using an Advanced Ice Cloud Microphysics in the WRF Model

Author

Tatsuo Onishi, Setigui Aboubacar Keita, Jean-Pierre Blanchet, Jean-Christophe Raut, Olivier Lemoine, Eric Girard, Jacques Pelon, Centre ESCER, Université du Québec à Montréal = University of Québec in Montréal (UQAM), 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), and Département des sciences de la terre et de l'atmosphère [Montréal] (SCTA)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, WRF, cloud microphysics, lcsh:QC851-999, [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology, Environmental Science (miscellaneous), 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, Arctic ice clouds, classical nucleation theory, 0105 earth and related environmental sciences, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Ice cloud, geography, geography.geographical_feature_category, Ice crystals, Microphysics, Arctic ice pack, Aerosol, ice nuclei acidification, numerical modeling, Lidar, 13. Climate action, Weather Research and Forecasting Model, Environmental science, lcsh:Meteorology. Climatology, Satellite
Abstract

Two Types of Ice Clouds (TICs) have been characterized in the Arctic during the polar night and early spring. TIC-1 are composed by non-precipitating small ice crystals of less than 30 &micro, m in diameter. The second type, TIC-2, are characterized by a low concentration of large precipitating ice crystals (&gt, 30 &micro, m). Here, we evaluate the Weather Research and Forecasting (WRF) model performance both in space and time after implementing a parameterization based on a stochastic approach dedicated to the simulation of ice clouds in the Arctic. Well documented reference cases provided us in situ data from the spring of 2008 Indirect and Semi-Direct Aerosol Campaign (ISDAC) campaign over Alaska. Simulations of the microphysical properties of the TIC-2 clouds on 15 and 25 April 2008 (polluted or acidic cases) and TIC-1 clouds on non-polluted cases are compared to DARDAR (raDAR/liDAR) satellite products. Our results show that the stochastic approach based on the classical nucleation theory, with the appropriate contact angle, is better than the original scheme in WRF model to represent TIC-1 and TIC-2 properties (ice crystal concentration and size) in response to the IN acidification.

Published
2019
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12. Added value of far-infrared radiometry for remote sensing of ice clouds

Author

Libois, Quentin, Blanchet, Jean-Pierre, Centre ESCER, and Université du Québec à Montréal = University of Québec in Montréal (UQAM)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere
Abstract

International audience; Several cloud retrieval algorithms based on satellite observations in the infrared have beendeveloped in the last decades. However these observations only cover the mid-infrared (MIR,λ < 15 μm) part of the spectrum, and none are available in the far-infrared (FIR, λ ≥ 15 μm).Using the optimal estimation method, we show that adding a few FIR channels to existingspaceborne radiometers would significantly improve their ability to retrieve ice cloud radia-tive properties. For clouds encountered in the polar regions and the upper troposphere, wherethe atmosphere is sufficiently transparent in the FIR, using FIR channels would reduce bymore than 50 % the uncertainties on retrieved values of optical thickness, particle effectivediameter and cloud top altitude. Notably, this would extend the range of applicability of cur-rent retrieval methods to the polar regions and to clouds with large optical thickness, whereMIR algorithms perform poorly. The high performance of solar reflection based algorithmswould thus be extended to nighttime conditions. Since the sensitivity of ice cloud thermalemission to particle effective diameter is approximately 5 times larger in the FIR than in theMIR, using FIR observations is a promising venue for studying ice cloud microphysics andprecipitation processes. This is highly relevant for cirrus clouds and convective towers. Thisis also essential to study precipitation in the driest regions of the atmosphere, where strongfeedbacks are at play between clouds and water vapor. The deployment in the near future of aFIR spaceborne radiometer is technologically feasible, and should be strongly supported.

Published
2017
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13. Impact of boreal wildfires on air quality: from regional to hemisphericscales

Author

Turquety, Solène, Mailler, Sylvain, Menut, Laurent, Sushama, Laxmi, Teufel, Bernado S., Hadji-Lazaro, Juliette, Whitburn, Simon, Coheur, Pierre-François, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Centre ESCER, Université du Québec à Montréal = University of Québec in Montréal (UQAM), 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), Spectroscopie de l'atmosphère, Service de Chimie Quantique et Photophysique, Université libre de Bruxelles (ULB), Cardon, Catherine, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
[SDE] Environmental Sciences, [SDE]Environmental Sciences
Abstract

International audience; Wildfires are a significant source of atmospheric pollutants, including greenhouse gases andaerosols. Among the emitted species, most have long enough lifetimes to be transported overthousands of kilometres. Boreal wildfires are particularly intense and have been shown tostrongly influence the interannual variability of several atmospheric pollutants (carbonmonoxide, CO, and aerosols) in the remote Northern Hemisphere. With a fire risk increasingand fire seasons lengthening as a result of climate change, it is all the more critical to betterestimate the large-scale impact from these large events.Here, the impact of boreal fires on regional air quality in Canada and in Europe (after longrangetransport) is estimated using a combination of satellite data analysis (IASI for CO,MODIS AOD and CALIOP lidar profiles for aerosols) and modelling with the CHIMEREregional chemistry-transport model. The fire emissions are calculated using the APIFLAMEemission model, including in particular a better representation of the potential burning of theground organic layer. Their variability will first be described for the time period 2013-2015.The performance of the model to simulate the local pollution levels and the influence fromlong-range transport (in the mid and high latitudes) will be discussed, focusing on the summerof 2013. The chemical evolution of the main plumes will then be evaluated using observationsof more reactive trace gases (NH3 from IASI, NO2 from GOME-2).

Published
2016

14. On the relationship between Arctic ice clouds and polluted air masses over the north slope of Alaska in April 2008

Author

Jacques Pelon, Gérard Ancellet, Jean-Pierre Blanchet, Julien Delanoë, Caroline Jouan, Eric Girard, 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), Centre ESCER, Université du Québec à Montréal = University of Québec in Montréal (UQAM), and SPACE - LATMOS

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Atmospheric sciences, 01 natural sciences, 010305 fluids & plasmas, lcsh:Chemistry, 0103 physical sciences, Precipitation, 0105 earth and related environmental sciences, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Pollutant, geography, geography.geographical_feature_category, Ice crystals, Humidity, Arctic ice pack, lcsh:QC1-999, Aerosol, lcsh:QD1-999, Volcano, 13. Climate action, Climatology, [SDE]Environmental Sciences, Ice nucleus, Environmental science, lcsh:Physics
Abstract

Recently, two Types of Ice Clouds (TICs) properties have been characterized using ISDAC airborne measurements (Alaska, April 2008). TIC-2B were characterized by fewer (110 μm) ice crystals, a larger ice supersaturation (>15%) and a fewer ice nuclei (IN) concentration (

Published
2013
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15. Characterization of Arctic ice cloud properties observed during ISDAC

Author

Jouan, Caroline, Girard, Eric, Pelon, Jacques, Gultepe, Ismail, Delanoë, Julien, Blanchet, Jean-Pierre, 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), Centre ESCER, Université du Québec à Montréal = University of Québec in Montréal (UQAM), SPACE - LATMOS, Environment and Climate Change Canada, and Natural Sciences and Engineering Research Council of Canada (NSERC),Fonds Québécois de la Recherche sur la Nature et la Technologie (FQRNT),Centre National d’Etudes Spatiales (CNES)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Arctic, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Ice cloud, ISDAC, Remote sensing, Cloud-aerosol interactions, Airborne measurements
Abstract

International audience; Extensive measurements from ground-based sites and satellite remote sensing (CloudSat and CALIPSO) reveal the existence of two types of ice clouds (TICs) in the Arctic during the polar night and early spring. The first type (TIC-2A), being topped by a cover of nonprecipitating very small (radar unseen) ice crystals (TIC-1), is found more frequently in pristine environment, whereas the second type (TIC-2B), detected by both sensors, is associated preferentially with a high concentration of aerosols. To further investigate the microphysical properties of TIC-1/2A and TIC-2B, airborne in situ and satellite measurements of specific cases observed during Indirect and Semi-Direct Aerosol Campaign (ISDAC) have been analyzed. For the first time, Arctic TIC-1/2A and TIC-2B microstructures are compared using in situ cloud observations. Results show that the differences between them are confined in the upper part of the clouds where ice nucleation occurs. TIC-2B clouds are characterized by fewer (by more than 1 order of magnitude) and larger (by a factor of 2 to 3) ice crystals and a larger ice supersaturation (of 15-20%) compared to TIC-1/2A. Ice crystal growth in TIC-2B clouds seems explosive, whereas it seems more gradual in TIC-1/2A. It is hypothesized that these differences are linked to the number concentration and the chemical composition of aerosols. The ice crystal growth rate in very cold conditions impinges on the precipitation efficiency, dehydration and radiation balance. These results represent an essential and important first step to relate previous modeling, remote sensing and laboratory studies with TICs cloud in situ observations.

Published
2012
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16. Development and testing scenarios for implementing land use and land cover changes during the Holocene in Earth system model experiments

Author

S. P. Harrison, M.-J. Gaillard, B. D. Stocker, M. Vander Linden, K. Klein Goldewijk, O. Boles, P. Braconnot, A. Dawson, E. Fluet-Chouinard, J. O. Kaplan, T. Kastner, F. S. R. Pausata, E. Robinson, N. J. Whitehouse, M. Madella, K. D. Morrison, University of Bristol [Bristol], Department of Biology and Environmental Sciences [Oldenburg], University of Oldenburg, Centre for Ecological Research and Forestry Applications (CREAF), University of Cambridge [UK] (CAM), PBL Netherlands Environmental Assessment Agency, University of Pennsylvania Museum of Archaeology and Anthropology (Penn Museum), 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), Modelling the Earth Response to Multiple Anthropogenic Interactions and Dynamics (MERMAID), 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), Department of Earth System Science [Stanford] (ESS), Stanford EARTH, Stanford University-Stanford University, Department of Earth Sciences [Hong kong], The University of Hong Kong (HKU), Senckenberg Biodiversity and Climate Research Centre (SBiK-F), Goethe-Universität Frankfurt am Main-Senckenberg – Leibniz Institution for Biodiversity and Earth System Research - Senckenberg Gesellschaft für Naturforschung, Leibniz Association-Leibniz Association, Centre ESCER, Université du Québec à Montréal = University of Québec in Montréal (UQAM), University of Wyoming, School of Geography, Earth and Environmental Sciences [Plymouth] (SoGEES), Plymouth University, Institució Catalana de Recerca i Estudis Avançats (ICREA), Department of Archaeology and Anthropology, University of Cambridge, Cambridge, UK, Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Environmental Sciences

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 010506 paleontology, education.field_of_study, 010504 meteorology & atmospheric sciences, Land use, Global climate, Population, lcsh:QE1-996.5, Land cover, 15. Life on land, Arqueologia, 01 natural sciences, Carbon cycle, lcsh:Geology, Ice core, 13. Climate action, Sòl, Ús del, Environmental science, Earth system model, Physical geography, education, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Holocene, 0105 earth and related environmental sciences, ddc:910
Abstract

International audience; Anthropogenic changes in land use and land cover (LULC) during the pre-industrial Holocene could have affected regional and global climate. Existing scenarios of LULC changes during the Holocene are based on relatively simple assumptions and highly uncertain estimates of population changes through time. Archaeological and palaeoenvironmental reconstructions have the potential to refine these assumptions and estimates. The Past Global Changes (PAGES) LandCover6k initiative is working towards improved reconstructions of LULC globally. In this paper, we document the types of archaeological data that are being collated and how they will be used to improve LULC reconstructions. Given the large methodological uncertainties involved, both in reconstructing LULC from the archaeological data and in implementing these reconstructions into global scenarios of LULC, we propose a protocol to evaluate Published by Copernicus Publications on behalf of the European Geosciences Union. 806 S. P. Harrison et al.: Development and testing scenarios for implementing land use and land cover changes the revised scenarios using independent pollen-based reconstructions of land cover and climate. Further evaluation of the revised scenarios involves carbon cycle model simulations to determine whether the LULC reconstructions are consistent with constraints provided by ice core records of CO 2 evolution and modern-day LULC. Finally, the protocol outlines how the improved LULC reconstructions will be used in palaeoclimate simulations in the Palaeoclimate Modelling Intercomparison Project to quantify the magnitude of anthro-pogenic impacts on climate through time and ultimately to improve the realism of Holocene climate simulations.

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17. Impact of Reduced Anthropogenic Emissions Associated With COVID-19 Lockdown on PM 2.5 Concentration and Canopy Urban Heat Island in Canada.

Author

Ashraf S, Pausata FSR, Leroyer S, Stevens R, and Munoz-Alpizar R

Abstract

Extensive lockdowns during the COVID-19 pandemic caused a remarkable decline in human activities that have influenced urban climate, especially air quality and urban heat islands. However, the impact of such changes on local climate based on long term ground-level observations has hitherto not been investigated. Using air pollution measurements for the four major Canadian metropolitan areas (Toronto, Montreal, Vancouver, and Calgary), we find that PM 2.5 markedly decreased during and after lockdowns with peak reduction ranging between 42% and 53% relative to the 2000-2019 reference period. Moreover, we show a substantial decline in canopy urban heat island intensity during lockdown and in the post lockdowns periods with peak reduction ranging between 0.7°C and 1.6°C in comparison with the 20-year preceding period. The results of this study may provide insights for local policymakers to define the regulation strategies to facilitate air quality improvement in urban areas., Competing Interests: The authors declare no conflicts of interest relevant to this study., (© 2025 The Author(s). GeoHealth published by Wiley Periodicals LLC on behalf of American Geophysical Union.)

Published
2025
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18. Climate change alone cannot explain boreal caribou range recession in Quebec since 1850.

Author

Morineau C, Boulanger Y, Gachon P, Plante S, and St-Laurent MH

Subjects
Animals, Humans, Quebec, Climate Change, Conservation of Natural Resources methods, Ecosystem, Reindeer
Abstract

The contraction of species range is one of the most significant symptoms of biodiversity loss worldwide. While anthropogenic activities and habitat alteration are major threats for several species, climate change should also be considered. For species at risk, differentiating the effects of human disturbances and climate change on past and current range transformations is an important step towards improved conservation strategies. We paired historical range maps with global atmospheric reanalyses from different sources to assess the potential effects of recent climate change on the observed northward contraction of the range of boreal populations of woodland caribou (Rangifer tarandus caribou) in Quebec (Canada) since 1850. We quantified these effects by highlighting the discrepancies between different southern limits of the caribou's range (used as references) observed in the past and reconstitutions obtained through the hindcasting of the climate conditions within which caribou are currently found. Hindcasted southern limits moved ~105 km north over time under all reanalysis datasets, a trend drastically different from the ~620 km reported for observed southern limits since 1850. The differences in latitudinal shift through time between the observed and hindcasted southern limits of distribution suggest that caribou range recession should have been only 17% of what has been observed since 1850 if recent climate change had been the only disturbance driver. This relatively limited impact of climate reinforces the scientific consensus stating that caribou range recession in Quebec is mainly caused by anthropogenic drivers (i.e. logging, development of the road network, agriculture, urbanization) that have modified the structure and composition of the forest over the past 160 years, paving the way for habitat-mediated apparent competition and overharvesting. Our results also call for a reconsideration of past ranges in models aiming at projecting future distributions, especially for endangered species., (© 2023 The Authors. Global Change Biology published by John Wiley & Sons Ltd.)

Published
2023
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19. Deciphering local and regional hydroclimate resolves contradicting evidence on the Asian monsoon evolution.

Author

Wolf A, Ersek V, Braun T, French AD, McGee D, Bernasconi SM, Skiba V, Griffiths ML, Johnson KR, Fohlmeister J, Breitenbach SFM, Pausata FSR, Tabor CR, Longman J, Roberts WHG, Chandan D, Peltier WR, Salzmann U, Limbert D, Trinh HQ, and Trinh AD

Abstract

The winter and summer monsoons in Southeast Asia are important but highly variable sources of rainfall. Current understanding of the winter monsoon is limited by conflicting proxy observations, resulting from the decoupling of regional atmospheric circulation patterns and local rainfall dynamics. These signals are difficult to decipher in paleoclimate reconstructions. Here, we present a winter monsoon speleothem record from Southeast Asia covering the Holocene and find that winter and summer rainfall changed synchronously, forced by changes in the Pacific and Indian Oceans. In contrast, regional atmospheric circulation shows an inverse relation between winter and summer controlled by seasonal insolation over the Northern Hemisphere. We show that disentangling the local and regional signal in paleoclimate reconstructions is crucial in understanding and projecting winter and summer monsoon variability in Southeast Asia., (© 2023. Springer Nature Limited.)

Published
2023
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20. Changes in freezing rain occurrence over eastern Canada using convection-permitting climate simulations.

Author

Marinier S, Thériault JM, and Ikeda K

Abstract

Freezing precipitation has major consequences for ground and air transportation, the health of citizens, and power networks. Previous studies using coarse resolution climate models have shown a northward migration of freezing rain in the future. Increased model resolution can better define local topography leading to improved representation of conditions that are favorable for freezing rain. The goal of this study is to examine the climatology and characteristics of future freezing rain events using very-high resolution climate simulations. Historical and pseudo-global warming simulations with a 4-km horizontal grid length were used and compared with available observations. Simulations revealed a northerly shift of freezing rain occurrence, and an increase in the winter. Freezing rain was still shown to occur in the Saint-Lawrence River Valley in a warmer climate, primarily due to stronger wind channeling. Up to 50% of the future freezing rain events also occurred in present day climate within 12 h of each other. In northern Maine, they are typically shorter than 6 h in current climate and longer than 6 h in warmer conditions due to the onset of precipitation during low-pressure systems occurrences. The occurrence of freezing rain also locally increases slightly north of Québec City in a warmer climate because of freezing rain that is produced by warm rain processes. Overall, the study shows that high-resolution regional climate simulations are needed to study freezing rain events in warmer climate conditions, because high horizontal resolutions better define small-scale topographic features and local physical mechanisms that have an influence on these events., (© The Author(s) 2022.)

Published
2023
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21. Respiratory and Otolaryngology Symptoms Following the 2019 Spring Floods in Quebec.

Author

Landaverde E, Généreux M, Maltais D, and Gachon P

Subjects
Humans, Odds Ratio, Quebec epidemiology, Respiratory System, Floods, Otolaryngology
Abstract

Background: Although floods may have important respiratory health impacts, few studies have examined this issue. This study aims to document the long-term impacts of the spring floods of 2019 in Quebec by (1) describing the population affected by the floods; (2) assessing the impacts on the respiratory system according to levels of exposure; and (3) determining the association between stressors and respiratory health., Methods: A population health survey was carried out across the six most affected regions 8-10 months post-floods. Data were collected on self-reported otolaryngology (ENT) and respiratory symptoms, along with primary and secondary stressors. Three levels of exposure were examined: flooded, disrupted and unaffected., Results: One in ten respondents declared being flooded and 31.4% being disrupted by the floods. Flooded and disrupted participants reported significantly more ENT symptoms (adjusted odds ratio (aOR): 3.18; 95% CI: 2.45-4.14; aOR: 1.76; 95% CI: 1.45-2.14) and respiratory symptoms (aOR: 3.41; 95% CI: 2.45-4.75; aOR: 1.45; 95% CI: 1.10-1.91) than the unaffected participants. All primary stressors and certain secondary stressors assessed were significantly associated with both ENT and respiratory symptoms, but no "dose-response" gradient could be observed., Conclusion: This study highlights the long-term adverse effects of flood exposure on respiratory health.

Published
2022
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22. ITCZ shift and extratropical teleconnections drive ENSO response to volcanic eruptions.

Author

Pausata FSR, Zanchettin D, Karamperidou C, Caballero R, and Battisti DS

Abstract

The mechanisms through which volcanic eruptions affect the El Niño-Southern Oscillation (ENSO) state are still controversial. Previous studies have invoked direct radiative forcing, an ocean dynamical thermostat (ODT) mechanism, and shifts of the Intertropical Convergence Zone (ITCZ), among others, to explain the ENSO response to tropical eruptions. Here, these mechanisms are tested using ensemble simulations with an Earth system model in which volcanic aerosols from a Tambora-like eruption are confined either in the Northern or the Southern Hemisphere. We show that the primary drivers of the ENSO response are the shifts of the ITCZ together with extratropical circulation changes, which affect the tropics; the ODT mechanism does not operate in our simulations. Our study highlights the importance of initial conditions in the ENSO response to tropical volcanic eruptions and provides explanations for the predominance of posteruption El Niño events and for the occasional posteruption La Niña in observations and reconstructions., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution License 4.0 (CC BY).)

Published
2020
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23. Tropical cyclone activity affected by volcanically induced ITCZ shifts.

Author

Pausata FSR and Camargo SJ

Abstract

Volcanic eruptions can affect global climate through changes in atmospheric and ocean circulation, and therefore could impact tropical cyclone (TC) activity. Here, we use ensemble simulations performed with an Earth System Model to investigate the impact of strong volcanic eruptions occurring in the tropical Northern (NH) and Southern (SH) Hemisphere on the large-scale environmental factors that affect TCs. Such eruptions cause a strong asymmetrical hemispheric cooling, either in the NH or SH, which shifts the Intertropical Convergence Zone (ITCZ) southward or northward, respectively. The ITCZ shift and the associated surface temperature anomalies then cause changes to the genesis potential indices and TC potential intensity. The effect of the volcanic eruptions on the ITCZ and hence on TC activity lasts for at least 4 years. Finally, our analysis suggests that volcanic eruptions do not lead to an overall global reduction in TC activity but rather a redistribution following the ITCZ movement. On the other hand, the volcanically induced changes in El Niño-Southern Oscillation (ENSO) or sea-surface temperature do not seem to have a significant impact on TC activity as previously suggested., Competing Interests: The authors declare no conflict of interest., (Copyright © 2019 the Author(s). Published by PNAS.)

Published
2019
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24. Tropical cyclone activity enhanced by Sahara greening and reduced dust emissions during the African Humid Period.

Author

Pausata FSR, Emanuel KA, Chiacchio M, Diro GT, Zhang Q, Sushama L, Stager JC, and Donnelly JP

Subjects
Africa, Northern, Climate Change, History, Ancient, Humidity, Plants, Climate, Computer Simulation, Cyclonic Storms, Dust, Ecosystem
Abstract

Tropical cyclones (TCs) can have devastating socioeconomic impacts. Understanding the nature and causes of their variability is of paramount importance for society. However, historical records of TCs are too short to fully characterize such changes and paleo-sediment archives of Holocene TC activity are temporally and geographically sparse. Thus, it is of interest to apply physical modeling to understanding TC variability under different climate conditions. Here we investigate global TC activity during a warm climate state (mid-Holocene, 6,000 yBP) characterized by increased boreal summer insolation, a vegetated Sahara, and reduced dust emissions. We analyze a set of sensitivity experiments in which not only solar insolation changes are varied but also vegetation and dust concentrations. Our results show that the greening of the Sahara and reduced dust loadings lead to more favorable conditions for tropical cyclone development compared with the orbital forcing alone. In particular, the strengthening of the West African Monsoon induced by the Sahara greening triggers a change in atmospheric circulation that affects the entire tropics. Furthermore, whereas previous studies suggest lower TC activity despite stronger summer insolation and warmer sea surface temperature in the Northern Hemisphere, accounting for the Sahara greening and reduced dust concentrations leads instead to an increase of TC activity in both hemispheres, particularly over the Caribbean basin and East Coast of North America. Our study highlights the importance of regional changes in land cover and dust concentrations in affecting the potential intensity and genesis of past TCs and suggests that both factors may have appreciable influence on TC activity in a future warmer climate., Competing Interests: The authors declare no conflict of interest.

Published
2017
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