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1. Radiative Budget in the Lower Tropical Stratosphere from the Combination of Balloon-Borne Lidar and Radiometric Measurements

Author

Ravetta, François, Lesigne, Thomas, Mariage, Vincent, Bureau, Jérôme, Hauchecorne, Alain, Pelon, Jacques, Sullivan, John T., editor, Leblanc, Thierry, editor, Tucker, Sara, editor, Demoz, Belay, editor, Eloranta, Edwin, editor, Hostetler, Chris, editor, Ishii, Shoken, editor, Mona, Lucia, editor, Moshary, Fred, editor, Papayannis, Alexandros, editor, and Rupavatharam, Krishna, editor

Published
2023
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5. Global perturbation of stratospheric water and aerosol burden by Hunga eruption

Author

Khaykin, Sergey, Podglajen, Aurelien, Ploeger, Felix, Grooß, Jens-Uwe, Tence, Florent, Bekki, Slimane, Khlopenkov, Konstantin, Bedka, Kristopher, Rieger, Landon, Baron, Alexandre, Godin-Beekmann, Sophie, Legras, Bernard, Sellitto, Pasquale, Sakai, Tetsu, Barnes, John, Uchino, Osamu, Morino, Isamu, Nagai, Tomohiro, Wing, Robin, Baumgarten, Gerd, Gerding, Michael, Duflot, Valentin, Payen, Guillaume, Jumelet, Julien, Querel, Richard, Liley, Ben, Bourassa, Adam, Clouser, Benjamin, Feofilov, Artem, Hauchecorne, Alain, and Ravetta, François

Published
2022
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9. Extensive coverage of ultrathin tropical tropopause layer cirrus clouds revealed by balloon-borne lidar observations.

Author

Lesigne, Thomas, Ravetta, François, Podglajen, Aurélien, Mariage, Vincent, and Pelon, Jacques

Subjects
CIRRUS clouds, TROPOPAUSE, LIDAR, WATER vapor, STRATOSPHERE, ATMOSPHERIC water vapor measurement
Abstract

Tropical tropopause layer (TTL) clouds have a significant impact on the Earth's radiative budget and regulate the amount of water vapor entering the stratosphere. Estimating the total coverage of tropical cirrus clouds is challenging, since the range of their optical depth spans several orders of magnitude, from thick opaque cirrus detrained from convection to sub-visible clouds just below the stratosphere. During the Strateole-2 observation campaign, three microlidars were flown on board stratospheric superpressure balloons from October 2021 to late January 2022, slowly drifting only a few kilometers above the TTL. These measurements have unprecedented sensitivity to thin cirrus and provide a fine-scale description of cloudy structures both in time and in space. Case studies of collocated observations with the spaceborne Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) show very good agreement between the instruments and highlight the Balloon-borne Cirrus and convective overshOOt Lidar's (BeCOOL) higher detection sensitivity. Indeed, the microlidar is able to detect optically very thin clouds (optical depth τ<2×10-3) that are undetected by CALIOP. Statistics on cloud occurrence show that TTL cirrus appear in about 50 % of the microlidar profiles and have a mean geometrical depth of 1 km. Ultrathin TTL cirrus (τ<2×10-3) have a significant coverage (23 % of the profiles), and their mean geometrical depth is 0.5 km. [ABSTRACT FROM AUTHOR]

Published
2024
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11. Analysis of ozone vertical profile day-to-day variability in the lower troposphere during the Paris-2022 ACROSS campaign.

Author

Ancellet, Gérard, Viatte, Camille, Boynard, Anne, Ravetta, François, Pelon, Jacques, Cailteau-Fischbach, Cristelle, Genau, Pascal, Capo, Julie, Roy, Axel, and Nédélec, Philippe

Abstract

The ozone vertical profiles variability in the lower troposphere is analyzed during the summer 2022 ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) measurement campaign as part of the PANAME (PAris region urbaN Atmospheric observations and models for Multidisciplinary rEsearch) project. The analysis is based on 21 days of DIfferential Absorption Lidar (DIAL) observations, in addition to the two daily vertical ozone profiles measured by In-service Aircraft for a Global Observing System (IAGOS) flights to and from Paris airport. The ACROSS ozone profiles are also a good opportunity to assess the lowermost tropospheric ozone column retrieval by the satellite observations of Infrared Atmospheric Sounding Interferometer (IASI). The planetary boundary layer (PBL) vertical structure evolution is monitored using a 808-nm microlidar and meteorological radiosondes launched in the city center. Characterization of the regional transport of polluted air masses advected over the city is based on the daily ozone analysis of the Copernicus Atmospheric Service (CAMS) ensemble model and on backward trajectories of the Paris city plume. This work show that the CAMS simulations of the Paris ozone plume between the surface and 3 km are consistent with the ACROSS ozone vertical profiles and that the IASI satellite observations can capture the day to day variability of the 0-3 km lowermost ozone column if the contribution of the surface column below 1.2 km is lower than 4 DU. The day time ozone vertical structure above the city center is also in good agreement with the PBL growth during the day and with the formation of the residual layer during the night. The O3 DIAL may provide additional information about the PBL vertical structure to discuss differences between microlidar and radiosounding measurements of the PBL height. In addition to the well-known control of the ozone photochemical production by atmospheric temperature, cloud cover and mixing between the surface layer (0 - 500 m) and the residual layer, the comparison of four ozone pollution events shows that the thickness of the PBL during the day and the advection of regional scale plumes above the PBL can significantly change the ozone concentrations above Paris city center. With similar cloud cover and air temperature, high ozone concentrations up to 180 µg.m-3 are encountered during the day when PBL height is below 1.5 km, while they remain below 150 µg.m-3 when PBL height increases above 2.5 km. Advection of ozone poor concentrations in the free troposphere during a Saharan dust event is able to mitigate the ozone photochemical production. On the other hand, the advection of a continental pollution plume with high ozone concentrations > 140 µg.m-3 maintained high concentrations in the surface layer despite a temperature decrease and cloud cover development. [ABSTRACT FROM AUTHOR]

Published
2024
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12. Evaluation and development of surface layer scheme representation of temperature inversions over boreal forests in Arctic wintertime conditions.

Author

Maillard, Julia, Raut, Jean-Christophe, and Ravetta, François

Subjects
TEMPERATURE inversions, TAIGAS, WIND speed, LOW temperatures, METEOROLOGICAL research, TUNDRAS, WINTER
Abstract

In this study, the Noah land surface model used in conjunction with the Mellor–Yamada–Janjić surface layer scheme (hereafter, Noah-MYJ) and the Noah multiphysics scheme (Noah-MP) from the Weather Research and Forecasting (WRF) 4.5.1 mesoscale model are evaluated with regard to their performance in reproducing positive temperature gradients over forested areas in the Arctic winter. First, simplified versions of the WRF schemes, recoded in Python, are compared with conceptual models of the surface layer in order to gain insight into the dependence of the temperature gradient on the wind speed at the top of the surface layer. It is shown that the WRF schemes place strong limits on the turbulent collapse, leading to lower surface temperature gradient at low wind speeds than in the conceptual models. We implemented modifications to the WRF schemes to correct this effect. The original and modified versions of Noah-MYJ and Noah-MP are then evaluated compared to long-term measurements at the Ameriflux Poker Flat Research Range, a forest site in interior Alaska. Noah-MP is found to perform better than Noah-MYJ because the former is a two-layer model which explicitly takes into account the effect of the forest canopy. Indeed, a non-negligible temperature gradient is maintained below the canopy at high wind speeds, leading to overall larger gradients than in the absence of vegetation. Furthermore, the modified versions are found to perform better than the original versions of each scheme because they better reproduce strong temperature gradients at low wind speeds. [ABSTRACT FROM AUTHOR]

Published
2024
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15. Observations of Tropical Tropopause Layer clouds from a balloon-borne lidar.

Author

Lesigne, Thomas, Ravetta, François, Podglajen, Aurélien, Mariage, Vincent, and Pelon, Jacques

Abstract

Tropical Tropopause Layer (TTL) clouds have a significant impact on the Earth's radiative budget and regulate the amount water vapor entering the stratosphere. During the Strateole-2 observation campaign, three microlidars were flown onboard stratospheric superpressure balloons from October 2021 to late January 2022, slowly drifting only a few kilometers above the TTL. These measurements have unprecedented sensitivity to thin cirrus and provide a fine-scale description of cloudy structures both in time and space. Case studies of collocated observations with the space-borne lidar Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) show a very good agreement between the instruments and highlight the unique ability of the microlidar to detect optically very thin clouds below CALIOP detection capacity (optical depth t < 2 · 10-3). Statistics on cloud occurrence show that TTL cirrus appear in more than 50 % of the microlidar profiles and have a mean geometrical depth 1 km. Ultrathin TTL cirrus (t < 2 · 10-3) have a significant coverage (16 % of the profiles) and their mean geometrical depth is below 500 m. [ABSTRACT FROM AUTHOR]

Published
2023
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16. Sources of upper tropospheric HOx over the South Pacific Convergence Zone: A case study

Author

Mari, Céline, Saüt, Carine, Jacob, Daniel J, Ravetta, François, Anderson, Bruce, Avery, Melody A, Blake, Donald R, Brune, William H, Faloona, Ian, Gregory, GL, Heikes, Brian G, Sachse, Glen W, Sandholm, Scott T, Singh, Hanwant B, Talbot, Robert W, Tan, David, and Vay, Stephanie

Subjects
Climate Action, HOx, convection, SPCZ, upper troposphere, PEM-TROPICS, Meteorology & Atmospheric Sciences
Published
2003

17. Evaluation of WRF 4.5.1 surface layer scheme representation of temperature inversions over boreal forests.

Author

Maillard, Julia, Raut, Jean-Christophe, and Ravetta, François

Subjects
TEMPERATURE inversions, TAIGAS, WIND speed, LOW temperatures, FOREST canopies
Abstract

In this study, the Noah Land Surface Model used in conjunction with the Mellor-Janji ć -Yamada surface layer scheme (hereafter, Noah-MYJ) and the Noah MultiPhysics scheme (Noah-MP) from the WRF 4.5.1 meso-scale model are evaluated with regards to their performance in reproducing positive temperature gradients over forested areas in the Arctic winter. First, simplified versions of the WRF schemes, recoded in Python, are compared with conceptual models of the surface layer in order to gain insight into the dependence of the temperature gradient on the wind speed at the top of the surface layer. It is shown that the WRF schemes place strong limits on the turbulent collapse, leading to lower surface temperature gradient at low wind speeds than in the conceptual models. We implemented modifications to the WRF schemes to correct this effect. The original and modified versions of Noah-MYJ and Noah-MP are then evaluated compared to long-term measurements at the Ameriflux Poker Flats Research Range, a forest site in Interior Alaska. Noah-MP is found to perform better than Noah-MYJ because the former is a 2-layer model which explicitly takes into account the effect of the forest canopy. Indeed a non-negligible temperature gradient is maintained below the canopy at high wind speeds, leading to overall larger gradients than in the absence of vegetation. Furthermore, the modified versions are found to perform better than the original versions of each scheme because they better reproduce strong temperature gradients at low wind speeds. [ABSTRACT FROM AUTHOR]

Published
2023
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18. BeCOOL: A Balloon-Borne Microlidar System Designed for Cirrus and Convective Overshoot Monitoring

Author

Ravetta François, Mariage Vincent, Brousse Emmanuel, d’Almeida Eric, Ferreira Frédéric, Pelon Jacques, and Victori Stéphane

Subjects
Physics, QC1-999
Abstract

A balloon-borne microlidar has been built at LATMOS to monitor cirrus optical properties and convective overshoot topography during long duration flights in the lower tropical stratosphere. Weighting less than 7 kg in a reduced volume and consuming less than 10 W, it will be involved in the CNES-Strateole2 campaign. This instrument paves the way to the use of microlidar technology for planetary missions.

Published
2020
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19. Ozone Lidar Observations in the City of Paris: Seasonal Variability and Role of The Nocturnal Low Level Jet

Author

Ancellet Gérard, Ravetta François, Pelon Jacques, Pazmino Andrea, Klein Amélie, Dieudonné Elsa, Augustin Patrick, and Delbarre Hervé

Subjects
Physics, QC1-999
Abstract

Ozone lidar measurements have been carried out in Paris during 4 years to characterize the seasonal variability of the vertical gradient within the urban planetary boundary layer (PBL). The interaction between NOx emission and thermal stability of the PBL is the main driver of the winter strong positive O3 gradient, while summer neutral gradient is related to weaker thermal stability and photochemical ozone production at the regional scale. Simultaneous lidar measurements of ozone and wind vertical profiles during 36 hours in September 2014 also show that the nocturnal low level jet (NLLJ) plays a significant role in the early morning ozone increase.

Published
2020
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20. Doppler Lidar Wind Profiling in Fairbanks (Interior of Alaska) During the 2022 ALPACAField Campaign

Author

Dieudonné, Elsa, Brett, Natalie, Fochesatto, Gilberto Javier, Raut, Jean-Christophe, d'Anna, B., Termine-Roussel, Brice, Schmale, Julia, Pohorsky, Roman, Baccarini, Andrea, Barret, Blandine, Delbarre, Hervé, Bekki, Slimane, Ravetta, François, Law, Kathy S., Laboratoire de Physico-Chimie de l'Atmosphère (LPCA), Université du Littoral Côte d'Opale (ULCO), 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), University of Alaska [Fairbanks] (UAF), Laboratoire Chimie de l'environnement (LCE), Aix Marseille Université (AMU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Ecole Polytechnique Fédérale de Lausanne (EPFL), 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), 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 -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
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]
Abstract

International audience

Published
2022

21. Global perturbation of stratospheric water and aerosol burden by Hunga eruption

Author

Khaykin, Sergey, primary, Podglajen, Aurelien, additional, Ploeger, Felix, additional, Grooß, Jens Uwe, additional, Tencé, Florent, additional, Bekki, Slimane, additional, Khlopenkov, Konstantin, additional, Bedka, Kristopher, additional, Rieger, Landon, additional, Baron, Alexandre, additional, Godin-Beekmann, Sophie, additional, Legras, Bernard, additional, Sellitto, Pasquale, additional, Sakai, Tetsu, additional, Barnes, John, additional, Uchino, Osamu, additional, Morino, Isamu, additional, Nagai, Tomohiro, additional, Wing, Robin, additional, Baumgarten, Gerd, additional, Gerding, Michael, additional, Duflot, Valentin, additional, Payen, Guillaume, additional, Jumelet, Julien, additional, Querel, Richard, additional, Liley, Ben, additional, Bourassa, Adam, additional, Hauchecorne, Alain, additional, Ravetta, François, additional, Clouser, Benjamin, additional, and Feofilov, Artem, additional

Published
2022
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22. Doppler Lidar Wind Profiling in Fairbanks (Interior of Alaska) During the 2022 ALPACA Field Campaign

Author

Dieudonné, Elsa, primary, Brett, Natalie, additional, Fochesatto, Gilberto J., additional, Raut, Jean-Christophe, additional, D'Anna, Barbara, additional, Temime-Roussel, Brice, additional, Schmale, Julia, additional, Pohorsky, Roman, additional, Baccarini, Andrea, additional, Barret, Brice, additional, Decesari, Stefano, additional, Donateo, Antonio, additional, Pappaccogli, Gianluca, additional, Scoto, Federico, additional, Busetto, Maurizio, additional, Delbarre, Hervé, additional, Bekki, Slimane, additional, Ravetta, François, additional, and Law, Kathy S., additional

Published
2022
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24. Sources and Processes Influencing Local Arctic Wintertime Air Pollution

Author

Law, Kathy S., Brett, Natalie, Raut, Jean-Christophe, Onishi, Tatsuo, Ravetta, François, Dieudonné, Elsa, Barret, Brice, Fochesatto, Gilberto Javier, Arnold, Steven, Temime-Roussel, Brice, d'Anna, B., Albertin, Sarah, Cesler‐maloney, Meeta, Simpson, William, Mao, Jingqiu, Roberts, Tjarda, Pohorsky, Roman, Baccarini, Andrea, Schmale, Julia, Decesari, Stefano, Donateo, Antonio, Pappaccogli, Gianluca, Scoto, Federico, Gilliam, Robert, Fahey, Kathleen, Cardon, Catherine, 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), Aix Marseille Université (AMU), Laboratoire Chimie de l'environnement (LCE), Aix Marseille Université (AMU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), TROPO - 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 de Physico-Chimie de l'Atmosphère (LPCA), Université du Littoral Côte d'Opale (ULCO), 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), University of Alaska [Fairbanks] (UAF), University of Leeds, Department of Chemistry and Biochemistry [Fairbanks], Geophysical Institute [Fairbanks], Ecole Polytechnique Fédérale de Lausanne (EPFL), CNR Institute of Atmospheric Sciences and Climate (ISAC), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), and US Environmental Protection Agency (EPA)

Subjects
[SDE] Environmental Sciences, [SDU]Sciences of the Universe [physics], [SDE]Environmental Sciences
Abstract

International audience; Wintertime Arctic air pollution is influenced by long-range transport of remote sources and local within-Arctic sources contributing to the build up of Arctic haze. Local emissions and resulting ground-level pollutant abundances are enhanced during cold winters especially during cold stable episodes with strong surface temperature inversions and light winds that limit pollutant dispersion, and lead to air quality exceedances. Fairbanks in Interior Alaska is a city with episodes of severe wintertime pollution. However, there are many uncertainties in our understanding about pollution sources and secondary aerosol formation under cold, dark winter conditions, when photochemistry is limited. The role of meteorological processes in the Arctic boundary layer is also poorly understood and often difficult to model. These issues were comprehensively examined through the collection of datasets on atmospheric composition and meteorology during the international ALPACA (Alaskan Layered Pollution and Chemical Analysis) field campaign in January and February 2022 in Fairbanks. One goal is to understand how meteorological processes influence surface, and vertical distributions, of aerosols and trace gases. Here, we analyze a combination of measurements collected at sites experiencing different pollution levels, including surface aerosol composition, trace gas profiles collected on a tethered balloon (EPFL helikite), wind lidar and other meteorological measurements. An overview of the different measurements will be presented as a function of meteorological conditions, in particular atmospheric stability. Particular episodes will be highlighted showing evidence for vertical exchange (turbulence) or possible influence from elevated power plant stack emissions. Particle dispersion modelling is used to examine emission sources contributing to surface pollution episodes and elevated plumes. The regional extent of pollution from the Fairbanks area will also be considered and compared to pollutant levels in background Arctic Haze air masses. This study contributes to air Pollution in the Arctic: Climate, Environment and Societies (PACES)-ALPACA. The French contribution is part of the CASPA (Climate-relevant Aerosol Sources and Processes in the Arctic)/IPEV project.

Published
2022

25. The marbll experiment: towards a martian wind lidar

Author

Määttänen Anni, Ravetta François, Montmessin Franck, Bruneau Didier, Mariscal Jean-François, Van Haecke Mathilde, Fayolle Guillaume, Montaron Christophe, and Coscia David

Subjects
Physics, QC1-999
Abstract

Operating a lidar on Mars would fulfill the need of accessing wind and aerosol profiles in the atmospheric boundary layer. This is the purpose of the MARs Boundary Layer Lidar (MARBLL) instrument. We report recent developments of this compact direct-detection wind lidar designed to operate from the surface of Mars. A new laser source has been developed and an azimuthal scanning capability has been added. Preliminary results of a field campaign are presented.

Published
2018
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27. The first flights of the Strateole-2 technology demonstration campaign: Observing the global equatorial tropopause with long-duration balloons

Author

Haase, Jennifer S., Alexander, M. Joan, Cocquerez, Philippe, Davis, Sean M., Deshler, Terry, Durry, Georges, Hauchecorne, Alain, Hertzog, Albert, Kalnajs, Lars, Plougonven, Riwal, Ravetta, François, Renard, Jean-Baptiste, University of California [San Diego] (UC San Diego), University of California, NorthWest Research Associates [Boulder] (NWRA), Centre National d'Études Spatiales [Toulouse] (CNES), NOAA Earth System Research Laboratory (ESRL), National Oceanic and Atmospheric Administration (NOAA), Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado [Boulder]-National Oceanic and Atmospheric Administration (NOAA), University of Wyoming (UW), Groupe de spectrométrie moléculaire et atmosphérique (GSMA), Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS), STRATO - 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), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS 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), University of Colorado [Boulder], TROPO - LATMOS, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), and Cardon, Catherine

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [PHYS.PHYS.PHYS-AO-PH] Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]
Abstract

International audience; Strateole-2 is an international initiative aimed at advancing knowledge of the global tropical tropopause. The originality of the project stems from the use of superpressure balloons (SPB) that fly for several months at altitudes of 18-20 km, sampling a stratospheric air mass directly and continuously, in a way that cannot be achieved with any other land-based or satellite observing system. SPBs are advected by the wind on constant-density surfaces, and therefore behave as quasi-Lagrangian tracers. A preparatory campaign was held beginning in November 2019. Eight SPBs were launched from Mahé, Seychelles Islands, and flew until late February 2020, achieving a mean flight duration of nearly 3 months in the tropics (85 days). Several balloons achieved more than one full circumnavigation of the Earth. Five different instrument configurations carried by the balloons provided information on the physics, dynamics, particle counts, and greenhouse gas composition of the sampled air parcels. Some instruments also sampled the atmospheric profile below the balloons, such as the Radio OCcultation instrument (ROC2), which provided more than 50 profiles per day of the upper troposphere / lower stratosphere, and the RaCHUTS reel-down in-situ sensor that sampled the tropical tropopause layer. Real-time in-situ measurements were assimilated by Numerical Weather Prediction centers. Preliminary results from several of the instruments will be described. The same instruments will be flown during two forthcoming campaigns in late 2021 and late 2024, with 20 balloons each, to further investigate wave generation by convection, wave driving of the QBO, and transport at the tropical tropopause. Observations will also contribute to the validation of recent spaceborne wind-lidar observations provided by the Aeolus mission.

Published
2020

29. Late Summer Ozone Variability in the Lower Troposphere of the Eastern Mediterranean

Author

Tsamalis Christoforos, Papayannis Alexandros, Ancellet Gerard, and Ravetta François

Subjects
Physics, QC1-999
Abstract

During the STAAARTE 96 Hellen aircraft campaign the lidar ALTO together with in situ measurements examined the ozone and aerosols variability in the lower troposphere over the Eastern Mediterranean region. Ozone mean value in the free troposphere (FT) measured from ALTO was 48 ppb, while it was 45 ppb from in situ observations; the aerosols mean scattering coefficient (550 nm) was 31 Mm−1. The FT ozone distributions of the two instruments are significantly different to distinct sampling. Air masses origin examination using the FLEXPART model for low and high FT ozone observations during late summer indicate that low ozone masses come from Mediterranean/North Africa regions travelling at low altitude, while high ozone masses emanate from Europe’s middle or upper troposphere.

Published
2016
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30. Impacts of Organics-Rich and Porous Interplanetary Dust Particles in the Earth’s Atmosphere

Author

Levasseur-Regourd, Anny Chantal, Hauchecorne, Alain, Lasue, Jérémie, Ravetta, François, Renard, Jean-Baptiste, PLANETO - 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), STRATO - LATMOS, Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), TROPO - LATMOS, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES)

Subjects
[SDU]Sciences of the Universe [physics], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2019

33. Stratéole 2: An Ultra Long Duration Super Pressure Balloon Campaign to Study the Equatorial Upper Troposphere and Lower Stratosphere

Author

Kalnajs, L., Hertzog, Albert, Cocquerez, Philippe, Alexander, M. J., Davis, Sean M., Deshler, T., Durry, Georges, Haase, J. S., Hauchecorne, Alain, Plougonven, Riwal, Ravetta, François, Renard, Jean-Baptiste, Vénel, Stephanie, University of Colorado [Boulder], Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS 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 d'Études Spatiales [Toulouse] (CNES), NorthWest Research Associates [Boulder] (NWRA), NOAA Earth System Research Laboratory (ESRL), National Oceanic and Atmospheric Administration (NOAA), Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado [Boulder]-National Oceanic and Atmospheric Administration (NOAA), Department of Atmospheric Science [Laramie], University of Wyoming (UW), Groupe de spectrométrie moléculaire et atmosphérique (GSMA), Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS), University of California [San Diego] (UC San Diego), University of California, STRATO - 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), TROPO - LATMOS, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]
Abstract

International audience; Stratéole 2 is an international collaboration to deploy constellations of equator-orbiting super pressure balloons to probe the Tropical Tropopause Layer (TTL) and equatorial lower stratosphere. The project comprises three flight campaigns in early 2019, late 2020 and late 2023 in which constellations of 5, 20 and 20 balloons will be launched from the Seychelle islands (4°S). The super pressure balloon system and flight control gondola, 'Euros' has been developed by CNES as a follow to the highly successful Concordiasi campaign in the Antarctic and Pre-Concordiasi campaign at the equator. There are two balloon configurations: a stratospheric configuration with 13m diameter balloons that will fly near 20km and a TTL configuration with 11m diameter balloons that will fly near 18km at the upper edge of the TTL. Flight durations of over 3 months are planned with a flight domain circling the equator and spanning from 20°S to 15°N. Scientific instruments are carried on a modular science gondola, 'Zephyr', developed at LATMOS, which is configurable to support up to four instruments per gondola, with each instrument combination chosen to target specific science questions. A suite of 12 instrument has been developed by both US and French institutions specifically for this project and consist of in situ measurements of aerosols, water vapor, methane, ozone, pressure, winds and temperature profiles, and remotely sensed measurements of temperature profiles, longwave radiation and cloud and aerosol backscatter. The scientific goals of Stratéole 2 are wide reaching and include investigating the dynamics and thermal structure of the TTL, dehydration of air entering the stratosphere, chemical and aerosol transport near the TTL, multiscale equatorial waves and largescale circulations such as the Quasi Biennial Oscillation (QBO).

Published
2018

34. Ozone Lidar Observations in the City of Paris: Seasonal Variability and Role of The Nocturnal Low Level Jet.

Author

Liu, D., Wang, Y., Wu, Y., Gross, B., Moshary, F., Ancellet, Gérard, Ravetta, François, Pelon, Jacques, Pazmino, Andrea, Klein, Amélie, Dieudonné, Elsa, Augustin, Patrick, and Delbarre, Hervé

Subjects
OZONE, LIDAR, THERMAL stability, EMISSIONS (Air pollution)
Abstract

Ozone lidar measurements have been carried out in Paris during 4 years to characterize the seasonal variability of the vertical gradient within the urban planetary boundary layer (PBL). The interaction between NOx emission and thermal stability of the PBL is the main driver of the winter strong positive O3 gradient, while summer neutral gradient is related to weaker thermal stability and photochemical ozone production at the regional scale. Simultaneous lidar measurements of ozone and wind vertical profiles during 36 hours in September 2014 also show that the nocturnal low level jet (NLLJ) plays a significant role in the early morning ozone increase. [ABSTRACT FROM AUTHOR]

Published
2020
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35. Diurnal, synoptic and seasonal variability of atmospheric CO2 in the Paris megacity area

Author

Xueref-Remy, Irène, Dieudonné, Elsa, Vuillemin, Cyrille, Lopez, Morgan, Lac, Christine, Schmidt, Martina, Delmotte, Marc, Chevallier, Frédéric, Ravetta, François, Perrussel, Olivier, Ciais, Philippe, Breon, Francois-Marie, Broquet, Grégoire, Ramonet, Michel, Gerard Spain, T., Ampe, Christophe, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut méditerranéen de biodiversité et d'écologie marine et continentale (IMBE), Avignon Université (AU)-Aix Marseille Université (AMU)-Institut de recherche pour le développement [IRD] : UMR237-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physico-Chimie de l'Atmosphère (LPCA), Université du Littoral Côte d'Opale (ULCO)-Centre National de la Recherche Scientifique (CNRS), European Organization for Nuclear Research (CERN), Environment and Climate Change Canada, 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 für Umweltphysik [Heidelberg], Universität Heidelberg [Heidelberg], ICOS-RAMCES (ICOS-RAMCES), 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), Modélisation INVerse pour les mesures atmosphériques et SATellitaires (SATINV), 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), AIRPARIF - Surveillance de la qualité de l'air en Île-de-France, ICOS-ATC (ICOS-ATC), National University of Ireland [Galway] (NUI Galway), Agence Nationale de la Recherche (ANR), Ville de Paris through the 'Le CO2 parisien' (Paris 2030) project., ANR-09-BLAN-0222,CO2-MEGAPARIS,Quantification des émissions de CO2 en Ile-de-France(2009), 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), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Universität Heidelberg [Heidelberg] = Heidelberg University, 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), and 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)

Subjects
[SDE]Environmental Sciences
Abstract

International audience; Most of the global fossil fuel CO2 emissions arise out of urbanized and industrialized areas. Bottom-up inventories quantify them but with large uncertainties. In 2010–2011, the first atmospheric in-situ CO2 measurement network for Paris, the capital of France, has been operated with the aim of monitoring the regional atmospheric impact of the emissions out coming from this megacity. Five stations sampled air along a northeast-southwest axis that corresponds to the direction of the dominant winds. Two stations are classified as rural (TRN and MON), two are peri-urban (GON and GIF) and one is urban (EIF, located on top of the Eiffel tower). In this study, we analyze the diurnal, synoptic and seasonal variability of the in-situ CO2 measurements over nearly one year (8 August 2010–13 July 2011). We compare these datasets with remote CO2 measurements made at Mace Head (MHD) on the Atlantic coast of Ireland, and support our analysis with atmospheric boundary layer height (ABLH) observations made in the centre of Paris and with both modeled and observed meteorological fields. The average hourly CO2 diurnal cycles observed at the regional stations are mostly driven by the CO2 biospheric cycle, the ABLH cycle, and the proximity to urban CO2 emissions. Differences of several μmol mol−1 (ppm) can be observed from one regional site to the other. The more the site is surrounded by urban sources (mostly traffic, residential and commercial heating), the more the CO2 concentration is elevated, as is the associated variability which reflects the variability of the urban sources. Furthermore, two elevated sites (EIF and TRN) show a phase shift of the CO2 diurnal cycle of a few hours compared to lower sites due to a strong coupling with the boundary layer diurnal cycle. As a consequence, the existence of a CO2 vertical gradient above Paris can be inferred, whose amplitude depends on the time of the day and on the season, ranging from a few tenths of ppm during daytime to several ppm during nighttime. The CO2 seasonal cycle inferred from monthly means at our regional sites are driven by the biospheric and anthropogenic CO2 flux seasonal cycles, by the ABLH seasonal cycle and also by synoptic variations. Gradients of several ppm are observed between the rural and peri-urban stations, mostly from the influence of urban emissions that are in the footprint of the peri-urban station. The seasonal cycle observed at the urban station (EIF) is specific and very sensitive to the ABLH cycle. At both the diurnal and the seasonal scales, noticeable differences of several ppm can be observed between the measurements made at regional rural stations and the remote measurements made at MHD, that are shown not to define background concentrations appropriately for quantifying the regional atmospheric impact of urban CO2 emissions. For wind speeds less than 3 m s−1, the accumulation of the local CO2 emissions in the urban atmosphere forms a dome of several tens of ppm at the peri-urban stations, mostly under the influence of relatively local emissions including those from the Charles-De-Gaulle (CDG) airport facility and from aircrafts in flight. When wind speed increases, ventilation transforms the CO2 dome into a plume. Higher CO2 background concentrations of several ppm are advected from the remote Benelux-Ruhr and London regions, impacting concentrations at the five stations of the network even at wind speeds higher than 9 m s−1. For wind speeds ranging between 3 and 8 m s−1, the impact of Paris emissions can be detected in the peri-urban stations when they are downwind of the city, while the rural stations often seem disconnected from the city emission plume. As a conclusion, our study highlights a high sensitivity of the stations to wind speed and direction, to their distance from the city, but also to the ABLH cycle depending on their elevation. We learn some lessons regarding the design of an urban CO2 network: 1/ careful attention should be paid to properly setting background sites that will be representative of the different wind sectors; 2/ the downwind stations should as much as possible be positioned symmetrically in relation to the city centre, at the peri-urban/rural border; 3/ the stations should be installed at ventilated sites (away from strong local sources) and the air inlet set-up above the building or biospheric canopy layer, whichever is the greatest; and 4/ high resolution wind information should be available with the CO2 measurements.

Published
2018

36. Characterisation and surface radiative impact of Arctic low clouds from the IAOOS field experiment.

Author

Maillard, Julia, Ravetta, François, Raut, Jean-Christophe, Mariage, Vincent, and Pelon, Jacques

Abstract

The Ice, Atmosphere, Arctic Ocean Observing System (IAOOS) field experiment took place from 2014 to 2019. Over this period, more than 20 instrumented buoys were deployed at the North Pole. Once locked into the ice, the buoys drifted for periods of a month to more than a year. Some of these buoys were equipped with 808 nm wavelength lidars which acquired a total of 1805 profiles over the course of the campaign. This IAOOS lidar dataset is exploited to establish a novel statistic of cloud cover and of the geometrical and optical characteristics of the lowest cloud layer. Cloud frequency is globally at 75%, and above 85% from May to October. Single layers are thickest in October/November and thinnest in the summer. Meanwhile, their optical depth is maximum in October. On the whole, the cloud cover is very low, with the great majority of first layer bases beneath 120 m. In the shoulder seasons, surface temperatures are markedly warmer when the IAOOS profile contains at least one low cloud than when it does not. This temperature difference is statistically insignificant in the summer months. Indeed, summer clouds have a shortwave cooling effect which can reach -60W m-2 and balance out their longwave warming effect. [ABSTRACT FROM AUTHOR]

Published
2020
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38. Distribution, optical properties, and radiative effect of pollution aerosols in the western mediter- ranean basin from TRAQA and SAFMED airborne observations

Author

Di Biagio, Claudia, Gaimoz, Cécile, Grand, Noël, Ancellet, Gérard, Attié, Jean-Luc, Beekmann, Matthias, Borbon, Agnès, Bucci, Silvia, Doppler, Lionel, Dubuisson, Philippe, Fierli, Federico, Mallet, Marc, Raut, Jean-Christophe, Ravetta, François, Sartelet, Karine, Formenti, Paola, Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), 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), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'aérologie (LAERO), 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, Dipartimento di Fisica [Ferrara], Università degli Studi di Ferrara (UniFE), CNR Institute of Atmospheric Sciences and Climate (ISAC), Consiglio Nazionale delle Ricerche (CNR), Freie Universität Berlin, Deutscher Wetterdienst [Offenbach] (DWD), Laboratoire d’Optique Atmosphérique - UMR 8518 (LOA), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Centre d'Enseignement et de Recherche en Environnement Atmosphérique (CEREA), École des Ponts ParisTech (ENPC)-EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), Agence Nationale de la Recherche, Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Ferrara = University of Ferrara (UniFE), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Cardon, Catherine, Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'aérologie (LA), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-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 Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-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), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-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)

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

International audience; Pollution aerosols strongly influence the composition of the western Mediterranean basin, but at present little is known on their distribution, optical properties and radiative effects. We report in this study in situ observations of pollution aerosol plumes obtained over the sea in the western Mediterranean during the TRAQA (TRansport and Air QuAlity) and the SAFMED (Secondary Aerosol Formation in the MEDiterranean) airborne campaigns in summers 2012 and 2013 (Di Biagio et al, 2015). The TRAQA and SAFMED flights explored an extended region of the western Mediterranean between 40°-45°N latitude and 2°W-12°E longitude including the Gulf of Genoa, Southern France, the Gulf of Lion, and the Spanish coasts. Measurements were performed over the sea at various distances from the coastline and up to 5000 m altitude. TRAQA and SAFMED successfully measured a wide range of meteorological conditions which favoured the pollution export from different sources around the basin.

Published
2016

39. Continental pollution in the Western Mediterranean basin: large variability of the aerosol single scattering albedo and influence on the direct shortwave radiative effect

Author

Di Biagio, Claudia, Formenti, Paola, Doppler, Lionel, Gaimoz, Cécile, Grand, Noel, Ancellet, Gerard, Attié, Jean Luc, Bucci, Silvia, Dubuisson, Philippe, Fierli, Federico, Mallet, Marc, Ravetta, François, Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Deutscher Wetterdienst [Offenbach] (DWD), 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), 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), CNR Institute of Atmospheric Sciences and Climate (ISAC), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Laboratoire d’Optique Atmosphérique - UMR 8518 (LOA), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), INSU, ADEME, ANR, CNES, CTC (Corsica region), EU/FEDER, Météo-France, CEA, ADEME/PRIMEQUAL, MISTRALS/ChArMEx programmes, Observatoire Midi-Pyrénées, Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-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), Consiglio Nazionale delle Ricerche (CNR), 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, Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'aérologie (LA), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3)

Subjects
Atmospheric Science, Continental pollution Mediterranean aerosol, 010504 meteorology & atmospheric sciences, Single-scattering albedo, [SDE.MCG]Environmental Sciences/Global Changes, Solar zenith angle, 010501 environmental sciences, Sea spray, Atmospheric sciences, 01 natural sciences, lcsh:QC1-999, Aerosol, Plume, lcsh:Chemistry, Atmospheric radiative transfer codes, lcsh:QD1-999, 13. Climate action, Climatology, ChArMEx, Radiative transfer, Environmental science, 14. Life underwater, lcsh:Physics, Optical depth, 0105 earth and related environmental sciences
Abstract

Pollution aerosols strongly influence the composition of the Western Mediterranean basin, but at present little is known on their optical properties. We report in this study in situ observations of the single scattering albedo (ω) of pollution aerosol plumes measured over the Western Mediterranean basin during the TRAQA (TRansport and Air QuAlity) airborne campaign in summer 2012. Cases of pollution export from different source regions around the basin and at different altitudes between ∼ 160 and 3500 m above sea level were sampled during the flights. Data from this study show a large variability of ω, with values between 0.84–0.98 at 370 nm and 0.70–0.99 at 950 nm. The single scattering albedo generally decreases with the wavelength, with some exception associated to the mixing of pollution with sea spray or dust particles over the sea surface. The lowest values of ω (0.84–0.70 between 370 and 950 nm) are measured in correspondence of a fresh plume possibly linked to ship emissions over the basin. The range of variability of ω observed in this study seems to be independent of the source region around the basin, as well as of the altitude and aging time of the plumes. The observed variability of ω reflects in a large variability for the complex refractive index of pollution aerosols, which is estimated to span in the large range 1.41–1.77 and 0.002–0.097 for the real and the imaginary parts, respectively, between 370 and 950 nm. Radiative calculations in clear-sky conditions were performed with the GAME radiative transfer model to test the sensitivity of the aerosol shortwave Direct Radiative Effect (DRE) to the variability of ω as observed in this study. Results from the calculations suggest up to a 50 and 30 % change of the forcing efficiency (FE), i.e. the DRE per unit of optical depth, at the surface (−160/−235 W m−2 τ−1 at 60° solar zenith angle) and at the Top-Of-Atmosphere (−137/−92 W m−2 τ−1) for ω varying between its maximum and minimum value. This induces a change of up to an order of magnitude (+23/+143 W m−2 τ−1) for the radiative effect within the atmosphere.

Published
2016

40. Assessing the role of megacities on atmospheric CO2: results for Paris from the CO2- MegaParis project, France

Author

Xueref-Remy, Irène, Dieudonné, Elsa, Vuillemin, C., Lopez, M., Lac, C., Delmotte, M., Ravetta, François, Perrussel, O., Breon, Francois-Marie, Broquet, G., Schmidt, M., Chevallier, F., Masson, V., Ciais, P., Ramonet, M., Ampe, C., Ammoura, L., Gros, V., Baudic, A., Bonsang, B., 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), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), ICOS-RAMCES (ICOS-RAMCES), 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), 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), Modélisation INVerse pour les mesures atmosphériques et SATellitaires (SATINV), Institut für Umweltphysik [Heidelberg], Universität Heidelberg [Heidelberg], ICOS-ATC (ICOS-ATC), 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), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), 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), and Universität Heidelberg [Heidelberg] = Heidelberg University

Subjects
[SDE]Environmental Sciences
Abstract

International audience; On average, atmospheric CO2 increases in the atmosphere at a rate of about 2 parts per million (ppm) per year, due to the accumulation of about half of the anthropogenic CO2 emissions in the atmosphere (mostly from the combustion of fossil fuels), while the other half is being re-absorbed by the ocean and the continental biosphere. today, more than 70% of global fossil-fuel CO2 emissions come from punctual sources such as megacities. paris is the third megacity in europe and it emits about 15% of the total French emissions, while it covers only less than 2% of the national territory. Currently, most of the estimates of urban CO2 emissions are given by bottom-up CO2 emissions inventories, which rely on activity proxies and benchmarked emission factors. the associated uncertainties can be as high as several tenths of percents, especially when it comes to discriminate the CO2 urban emissions by emission sectors. therefore, there is an urgent need for developing new methods to better Monitoring, reporting and Veryfying (MrV) CO2 emissions from megacities, dedicated to provide robust results to policy makers for taking efficient decisions and actions in matter of controling CO2 anthropogenic emissions and mitigating climate change. since 2009, the CO2-Megaparis project aims to quantify CO2 emissions from paris using top-down approaches based on a synergy between atmospheric observations and modeling. For the first time, a mini-network of 3 greenhouse gases (GHG) monitoring stations was developed by lsCe in paris agglomeration within the infrastructure of the regional air quality monitoring agency, airpariF, completing 2 other GHG stations from the iCOs european greenhouse monitoring network. One of our urban station was located on top of the eiffel tower above paris megacity. the analysis of one year of data showed that paris CO2 emissions lead to a mean increase of the atmospheric CO2 concentration in the mid-afternoon of 2 to 3 ppm, and is strongly season, windspeed and wind direction dependent: the CO2 urban plume is characterized by a very large spatio-temporal variability and can reach about 60 ppm at low windspeeds on top of the eiffel tower. in addition, analysis of correlations between CO2, CO and 14C02 were carried out from field measurements and allowed an independent assessment of the inventories emission sectors. Furthermore, direct modeling of CO2 at a very fine resolution (2x2 km2, 1h) was performed and matched well with the observations. last but not least, inverse modeling efforts at the same resolution allowed a significant improvment of the regional inventory from airparif. Finally, a campaign conducted during springtime and based on lidar facilities revealed that due to the effect of the urban heat island, the boundary layer height (that can be seen on the first degree as the man dilution factor of CO2 emissions in the atmosphere), is 10 to 40% time higher in Paris than in surrounding rural areas: this is an important result that supports the implementation of urban canopy models in future fine scale urban CO2 modeling framework. a synthesis of the different results will be presented, as well as an attempt of defining the strengths and weaknesses of the atmospheric approach to quantify urban CO2 emissions. Contributions from sister studies (MultiCO2 - ipsl, le CO2 parisien - Ville de paris 2030, CarboCount-City - KiC Climat...) will also be mentionned.

Published
2015

41. Analysis of atmospheric properties and surface radiation budget using radiative transfer code MOMO

Author

Ravetta, François, Pelon, Jacques, Bureau, Jérôme, Mariage, Vincent, Doppler, Lionel, Hollstein, André, Fischer, J., 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), Department of Earth Sciences [Berlin], Free University of Berlin (FU), Fraunhofer Institute for Telecommunications - Heinrich Hertz Institute (Fraunhofer HHI), Fraunhofer (Fraunhofer-Gesellschaft), and Cardon, Catherine

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [PHYS.PHYS.PHYS-AO-PH] Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]
Abstract

International audience; Extension of radiative transfer code MOMO and validation. Application to IAOOS project combining ground-based and space observations

Published
2015

42. Analysis of the latitudinal variability of tropospheric ozone in the Arctic using the large number of aircraft and ozonesonde observations in early summer 2008

Author

Ancellet, Gerard, primary, Daskalakis, Nikos, additional, Raut, Jean Christophe, additional, Tarasick, David, additional, Hair, Jonathan, additional, Quennehen, Boris, additional, Ravetta, François, additional, Schlager, Hans, additional, Weinheimer, Andrew J., additional, Thompson, Anne M., additional, Johnson, Bryan, additional, Thomas, Jennie L., additional, and Law, Katharine S., additional

Published
2016
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43. Supplementary material to "Diurnal, synoptic and seasonal variability of atmospheric CO2 in the Paris megacity area"

Author

Xueref-Remy, Irène, primary, Dieudonné, Elsa, additional, Vuillemin, Cyrille, additional, Lopez, Morgan, additional, Lac, Christine, additional, Schmidt, Martina, additional, Delmotte, Marc, additional, Chevallier, Frédéric, additional, Ravetta, François, additional, Perrussel, Olivier, additional, Ciais, Philippe, additional, Bréon, François-Marie, additional, Broquet, Grégoire, additional, Ramonet, Michel, additional, Spain, T. Gerard, additional, and Ampe, Christophe, additional

Published
2016
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44. Diurnal, synoptic and seasonal variability of atmospheric CO&lt;sub&gt;2&lt;/sub&gt; in the Paris megacity area

Author

Xueref-Remy, Irène, primary, Dieudonné, Elsa, additional, Vuillemin, Cyrille, additional, Lopez, Morgan, additional, Lac, Christine, additional, Schmidt, Martina, additional, Delmotte, Marc, additional, Chevallier, Frédéric, additional, Ravetta, François, additional, Perrussel, Olivier, additional, Ciais, Philippe, additional, Bréon, François-Marie, additional, Broquet, Grégoire, additional, Ramonet, Michel, additional, Spain, T. Gerard, additional, and Ampe, Christophe, additional

Published
2016
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45. Diurnal, synoptic and seasonal variability of atmospheric CO2 in the Paris megacity area.

Author

Xueref-Remy, Irène, Dieudonné, Elsa, Vuillemin, Cyrille, Lopez, Morgan, Lac, Christine, Schmidt, Martina, Delmotte, Marc, Chevallier, Frédéric, Ravetta, François, Perrussel, Olivier, Ciais, Philippe, Bréon, François-Marie, Broquet, Grégoire, Ramonet, Michel, Spain, T. Gerard, and Ampe, Christophe

Subjects
ATMOSPHERIC carbon dioxide, FOSSIL fuels, ATMOSPHERIC boundary layer, MAGNETOHYDRODYNAMICS, CITIES & towns & the environment
Abstract

Most of the global fossil fuel CO2 emissions arise from urbanized and industrialized areas. Bottom-up inventories quantify them but with large uncertainties. In 2010-2011, the first atmospheric in situ CO2 measurement network for Paris, the capital of France, began operating with the aim of monitoring the regional atmospheric impact of the emissions coming from this megacity. Five stations sampled air along a northeast--southwest axis that corresponds to the direction of the dominant winds. Two stations are classified as rural (Traînou -- TRN; Montgé-en-Goële -- MON), two are peri-urban (Gonesse -- GON; Gif-sur-Yvette -- GIF) and one is urban (EIF, located on top of the Eiffel Tower). In this study, we analyze the diurnal, synoptic and seasonal variability of the in situ CO2 measurements over nearly 1 year (8 August 2010-13 July 2011).We compare these datasets with remote CO2 measurements made at Mace Head (MHD) on the Atlantic coast of Ireland and support our analysis with atmospheric boundary layer height (ABLH) observations made in the center of Paris and with both modeled and observed meteorological fields. The average hourly CO2 diurnal cycles observed at the regional stations are mostly driven by the CO2 biospheric cycle, the ABLH cycle and the proximity to urban CO2 emissions. Differences of several µmol mol-1(ppm) can be observed from one regional site to the other. The more the site is surrounded by urban sources (mostly residential and commercial heating, and traffic), the more the CO2 concentration is elevated, as is the associated variability which reflects the variability of the urban sources. Furthermore, two sites with inlets high above ground level (EIF and TRN) show a phase shift of the CO2 diurnal cycle of a few hours compared to lower sites due to a strong coupling with the boundary layer diurnal cycle. As a consequence, the existence of a CO2 vertical gradient above Paris can be inferred, whose amplitude depends on the time of the day and on the season, ranging from a few tenths of ppm during daytime to several ppm during nighttime. The CO2 seasonal cycle inferred from monthly means at our regional sites is driven by the biospheric and anthropogenic CO2 flux seasonal cycles, the ABLH seasonal cycle and also synoptic variations. Enhancements of several ppm are observed at peri-urban stations compared to rural ones, mostly from the influence of urban emissions that are in the footprint of the peri-urban station. The seasonal cycle observed at the urban station (EIF) is specific and very sensitive to the ABLH cycle. At both the diurnal and the seasonal scales, noticeable differences of several ppm are observed between the measurements made at regional rural stations and the remote measurements made at MHD, that are shown not to define background concentrations appropriately for quantifying the regional (~100 km) atmospheric impact of urban CO2 emissions. For wind speeds less than 3 m s-1, the accumulation of local CO2 emissions in the urban atmosphere forms a dome of several tens of ppm at the peri-urban stations, mostly under the influence of relatively local emissions including those from the Charles de Gaulle (CDG) Airport facility and from aircraft in flight. When wind speed increases, ventilation transforms the CO2 dome into a plume. Higher CO2 background concentrations of several ppm are advected from the remote Benelux--Ruhr and London regions, impacting concentrations at the five stations of the network even at wind speeds higher than 9 m s-1. For wind speeds ranging between 3 and 8 m s-1, the impact of Paris emissions can be detected in the peri-urban stations when they are downwind of the city, while the rural stations often seem disconnected from the city emission plume. As a conclusion, our study highlights a high sensitivity of the stations to wind speed and direction, to their distance from the city, but also to the ABLH cycle depending on their elevation. We learn some lessons regarding the design of an urban CO2 network: (1) careful attention should be paid to properly setting regional (~100 km) background sites that will be representative of the different wind sectors; (2) the downwind stations should be positioned as symmetrically as possible in relation to the city center, at the peri-urban/rural border; (3) the stations should be installed at ventilated sites (away from strong local sources) and the air inlet set up above the building or biospheric canopy layer, whichever is the highest; and (4) high-resolution wind information should be available with the CO2 measurements. [ABSTRACT FROM AUTHOR]

Published
2018
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46. Retrieval of Paris CO2 and CO emissions using a boundary layer budget method in the framework of the CO2-MEGAPARIS project

Author

Dieudonné, Elsa, Gibert, Fabien, Xueref-Remy, Irene C., Lopez, Morgan, Schmidt, Martina, Ravetta, François, 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), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Cardon, Catherine, 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), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)

Subjects
[SDE.MCG] Environmental Sciences/Global Changes, [SDE.MCG]Environmental Sciences/Global Changes, Physics::Atmospheric and Oceanic Physics
Abstract

International audience; The development of anthropogenic activities since the pre-industrial era has greatly increased CO2 concentrations in the atmosphere, very likely causing the observed rise in global temperature. Therefore, accurate estimations of CO2 emission fluxes are very important for climate predictions. At the continental scale, CO2 fluxes can be estimated rather precisely using inverse modeling while tower turbulent flux measurements (eddy-covariance or EC) can provide an estimation of local-scale fluxes. However, this method cannot be applied to monitor urban CO2 emissions due to their large horizontal variability, so that a regional scale approach seems more suited. Unfortunately, at this scale, anthropogenic and biospheric fluxes are mixed, diluted and advected in the atmospheric boundary-layer (ABL) and the balance between these processes is not well known. Yet, independent estimations of CO2 fluxes would be needed to verify existing high resolution emission inventories and assess the efficiency of future mitigation policies. Several experiments dedicated to quantifying CO2 emissions from megacities are ongoing, like the CO2-MEGAPARIS research project [a,b]. In this framework, a network of lidars and in-situ sensors has been set up in Paris region. An original ABL mass budget method is used to infer the properties of advected anthropogenic CO2 and CO emissions from Paris urban area [c]. The method is applied in the center of Paris, at neighboring suburban sites located 20 km away, and at a rural station (100 km downwind). The budget uses ABL depths from elastic lidars, CO2 and CO concentrations from both the ICOS [d] and CO2-MEGAPARIS networks to quantify vertical advection and storage terms in the ABL mass budget. EC measurements are used to monitor biospheric surface fluxes. The budget in Paris provides a direct estimation of the average CO2 and CO fluxes from the city, while the budget at the suburban and rural stations provides an estimation of the advected fluxes. These anthropogenic fluxes are compared to the CITEPA and IER emission inventories using the air mass footprint from a Lagrangian Particle Dispersion Model in backward mode. Results from a case study in March 2012 are presented to assess the propagation of Paris CO2 and CO plume, the precision of the method and its ability to provide an independent verification of urban emission inventories.

Published
2012

47. 1D radiative transfer simulation of complex aerosol-cloud structure. Sensitivity study and implication to regional forcing estimates

Author

Doppler, Lionel, Ravetta, François, Pelon, Jacques, Fischer, J., Institut für Meteorologie [Berlin], Freie Universität Berlin, 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), SPACE - LATMOS, and Cardon, Catherine

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [SDE.MCG] Environmental Sciences/Global Changes, [SDU.STU.CL] Sciences of the Universe [physics]/Earth Sciences/Climatology, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, [SDE.MCG]Environmental Sciences/Global Changes, [PHYS.PHYS.PHYS-AO-PH] Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Astrophysics::Galaxy Astrophysics, Physics::Atmospheric and Oceanic Physics
Abstract

The spatial distribution of aerosol and clouds in the atmosphere leads, in a significant number of cases, to the occurrence of a complex vertical stratification and large horizontal variability. This is especially the case when low and mid- level clouds are embedded over the ocean in absorbing aerosol layers near polluted areas or biomass burning regions. This implies at the same time difficulties to determine representative optical and microphysical properties in any vertical column from remote sensing observations, and problems to perform accurate radiation budget analysis at the regional scale. A set of representative cases for such complex aerosol and clouds structures has been looked at. The last version of the radiative transfer (RT) code MOMO (Matrix Operator MOdel) of Free University of Berlin has been used to simulate 1-D radiative transfer in shortwave (SW) and in longwave (LW) and perform sensitivity tests for a few representative cases. The parameters identified to characterize the impact of errors in RT simulations are: 1) the heights and thicknesses of aerosol and clouds layers, and 2) clouds and aerosol optical properties (cloud effective radius, cloud liquid water content, cloud phase, aerosol single scattering albedo, extinction coefficient, asymmetry factor). Simulations of radiative fluxes, spectral radiances and irradiances, net fluxes for different altitudes and radiative heating-rates in SW and LW have been performed using the above described parameters and background vertical profiles for temperature and moisture as inputs of the RT model. First application is the improvement of satellite retrievals of clouds properties. Indeed, for instrument channels used to retrieve the clouds properties, complex structures with embedded aerosol and clouds layers may lead to similar top of atmosphere spectral radiances as compared to single layer structures having other properties (e.g. an absorbing aerosol layer over warm clouds as in the Gulf of Guinea would impact the retrieval of cloud properties). Examples are given and discussed. Another application is the error analysis in the computation of radiative forcing in a given region, using similar typical aerosol and cloud structure as identified from observations. The sensitivity analysis is used to identify criticality of input parameters. Outputs are the top of atmosphere and surface radiative forcings for mixed aerosol and cloud layers. Uncertainties resulting from spatial or temporal variability are then discussed.

Published
2012

48. Panorama de la physique - nouvelle édition

Author

Auvray, Loïc, Berroir, Jean-Marc, Billy, Nicolas, Daudet, Laurent, Fabre, Claude, Laval, Katia, Madariaga, Raoul, Mégie, Gérard, Ollitrault, Jean-Yves, Oudar, Jean-Louis, Pietryk, Gilbert, Ravetta, François, Rezeau, Laurence, Uzan, Jean-Philippe, Vigny, Christophe, Rezeau, Laurence, Laboratoire de Physique des Plasmas (LPP), Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École polytechnique (X)-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], ComputingMilieux_MISCELLANEOUS, [PHYS] Physics [physics]
Abstract

International audience

Published
2012

49. Contribution of lidar observations to urban boundary layer NO2 analysis

Author

Dieudonné, Elsa, Ravetta, François, Pelon, Jacques, Goutail, Florence, Pazmino, Andrea, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), 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), STRATO - LATMOS, 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), and Cardon, Catherine

Subjects
[SDE] Environmental Sciences, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [SDE]Environmental Sciences, [PHYS.PHYS.PHYS-AO-PH] Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]
Abstract

The Paris agglomeration is a major source of pollutants that can stay trapped in the atmospheric boundary layer (BL), making BL depth a crucial parameter that modulates pollutant concentrations and peak intensity. It is commonly assumed that pollutants, except very short-lived species, are well mixed in the BL, implying that the BL integrated content (column) can easily compare with ground-based in-situ measurements using BL depth. On a few day case study chosen during the MEGAPOLI field campaign, we analyze Airparif in-situ air quality measurements at ground level and at the Eiffel Tower summit and interpret the differences using BL observations from an elastic backscatter lidar located in Qualair station, in central Paris. NO2 concentrations are generally higher in the surface layer than in the mixed layer meaning NO2 is not well distributed in the BL. During the afternoons of pollution peak days, the gradient is around -41 μg/m3/km but when the morning BL is rising there is no gradient. Then we calculate NO2 integrated columns, first assuming a constant concentration in the mixed layer and no surface layer. These calculated columns reproduce the temporal structure of the columns measured by the Qualair UV-visible spectrometer (SAOZ) but they are 4 time higher in average. Columns calculated using a linearly decreasing concentration profile fit better with the SAOZ and confirm the existence of a vertical NO2 gradient.

Published
2010

50. Shortwave radiative heating rate profiles in hazy and clear atmosphere: a sensitivity study

Author

Doppler, Lionel, Fischer, Jürgen, Ravetta, François, Pelon, Jacques, Preusker, René, Institut für Weltraumwissenschaften [Berlin], Freie Universität Berlin, 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), and SPACE - LATMOS

Subjects
[SDU]Sciences of the Universe [physics]
Abstract

International audience; Aerosols have an impact on shortwave heating rate profiles (additional heating or cooling). In this survey, we quantify the impact of several key-parameters on the heating rate profiles of the atmosphere with and without aerosols. These key-parameters are: (1) the atmospheric model (tropical, midlatitude summer or winter, US Standard), (2) the integrated water vapor amount (IWV ), (3) the ground surface (flat and rough ocean, isotropic surface albedo for land), (4) the aerosol composition (dusts, soots or maritimes mixtures with respect to the OPAC-database classification), (5) the aerosol optical depth and (6) vertical postion, and (7) the single-scattering albedo (?o) of the aerosol mixture. This study enables us to evaluate which parameters are most important to take into account in a radiative energy budget of the atmosphere and will be useful for a future study: the retrieval of heating rates profiles from satellite data (CALIPSO, MODIS, MERIS) over the Mediterranean Sea. All the heating rates are computed by using the vector irradiances computed at each pressure level in the spectral interval 0.2 - 3.6μm (shortwave) by the 1D radiative transfer model for atmosphere and ocean: MOMO (Matrix-Operator MOdel) of the Institute for Space Science, FU Berlin 1

Published
2010

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