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Laboratoire Interuniversitaire des Systèmes Atmosphériques

LISA

Tutelles >

Université Paris Diderot - Paris 7

UFR de rattachement >

UFR Chimie

Label unité >

UMR 7583

Présentation

Le LISA, Laboratoire Interuniversitaire des Systèmes Atmosphériques est une unité de recherche de structure originale dépendant des Universités Paris Est Créteil et Paris Diderot, et du CNRS (UMR CNRS 7583).

Le LISA compte environ 130 personnes, dont 50 enseignants-chercheurs et chercheurs (CNRS & IRD), 36 ITA-IATOS et environ 45 post-doctorants, doctorants et étudiants de Master.

Il dispose d'un important potentiel technique et expérimental réparti sur 3.600m² de locaux à Créteil et d'une antenne opérationnelle sur le site Paris Rive Gauche, incluant aussi des équipements lourds. Les recherches y sont développées autour d’un thème générale : l’Atmosphère (comme le nom du laboratoire l’indique), Ses principaux thèmes de recherche portent ainsi sur la compréhension du fonctionnement des atmosphères terrestres et planétaires, et des impacts liés à la modification de la composition de l'atmosphère par les activités humaines. Les méthodes utilisées sont fondées sur des observations en atmosphère réelle, sur de la simulation expérimentale en laboratoire et de la modélisation numérique.

Pour mener à bien ces recherches, le LISA regroupe des scientifiques de plusieurs disciplines : physiciens, géochimistes, environnementalistes et une majorité de chimistes. Ce dernier aspect est une de ses caractéristiques importantes par rapport aux autres laboratoires du domaine. Un département technique (doté de 4 pôles : chimie, instrumentation, terrain et informatique) et un département administratif sont en soutien des activités de recherche.

Thèmes de recherche

Pollution atmosphérique Oxydante et Particulaire
Devenir du Carbone Organique
Cycle de l’Aérosol Désertique
Spectroscopie et Atmosphères
Exobiologie et Astrochimie

[hal-02395847] Nonlinear behavior of organic aerosol in biomass burning plumes: a microphysical model analysis

Date: 30 Nov 2022 - 11:22

Desc: Organic aerosol (OA) is a major component of smoke plumes from open biomass burning (BB). Therefore, adequate representation of the atmospheric transformations of BB OA in chemistry-transport and climate models is an important prerequisite for accurate estimates of the impact of BB emissions on air quality and climate. However, field and laboratory studies of atmospheric transformations (ag-ing) of BB OA have yielded a wide diversity of observed effects. This diversity is still not sufficiently understood and thus not addressed in models. As OA evolution is governed by complex nonlinear processes, it is likely that at least a part of the observed variability in the BB OA aging effects is due to the factors associated with the intrinsic nonlinearity of the OA system. In this study, we performed a numerical analysis in order to gain a deeper understanding of these factors. We employ a microphysical dynamic model that represents gas-particle partitioning and OA oxidation chemistry within the volatility basis set (VBS) framework and includes a schematic parameterization of BB OA dilution due to dispersion of an isolated smoke plume. Several VBS schemes of different complexity, which have been suggested in the literature to represent BB OA aging in regional and global chemistry-transport models, are applied to simulate BB OA evolution over a 5 d period representative of the BB aerosol lifetime in the dry atmosphere. We consider the BB OA mass enhancement ratio (EnR), which is defined as the ratio of the mass concentration of BB OA to that of an inert tracer and allows us to eliminate the linear part of the dilution effects. We also analyze the behavior of the hygroscopicity parameter, κ, that was simulated in a part of our numerical experiments. As a result, five qualitatively different regimes of OA evolution are identified, which comprise (1) a monotonic saturating increase in EnR, (2) an increase in EnR followed by a decrease, (3) an initial rapid decrease in EnR followed by a gradual increase , (4) an EnR increase between two intermittent stages of its decrease, or (5) a gradual decrease in EnR. We find that the EnR for BB aerosol aged from a few hours to a few tens of hours typically increases for larger initial sizes of the smoke plume (and therefore smaller dilution rates) or for lower initial OA concentrations (and thus more organic gases available to form secondary OA-SOA). However, these dependencies can be weakened or even reversed, depending on the BB OA age and on the ratio between the fragmentation and functionalization oxidation pathways. Nonlinear behavior of BB OA is also exhibited in the dependencies of κ on the parameters of the plume. Application of the different VBS schemes results in large quantitative and qualitative differences between the simulations, although our analysis suggests also that the main qualitative features of OA evolution simulated with a complex two-dimensional VBS scheme can also be reproduced with a much simpler scheme. Overall, this study indicates that the BB aerosol evolution may strongly depend on parameters of the individual BB smoke plumes (such as the initial organic aerosol concentration and plume size) that are typically not resolved in chemistry-transport models.

[hal-02395826] Estimation of black carbon emissions from Siberian fires using satellite observations of absorption and extinction optical depths

Date: 30 Nov 2022 - 11:22

Desc: Black carbon (BC) emissions from open biomass burning (BB) are known to have a considerable impact on the radiative budget of the atmosphere at both global and regional scales; however, these emissions are poorly constrained in models by atmospheric observations, especially in remote regions. Here, we investigate the feasibility of constraining BC emissions from BB using satellite observations of the aerosol absorption optical depth (AAOD) and the aerosol extinction optical depth (AOD) retrieved from OMI (Ozone Monitoring Instrument) and MODIS (Moder-ate Resolution Imaging Spectroradiometer) measurements, respectively. We consider the case of Siberian BB BC emissions , which have the strong potential to impact the Arc-tic climate system. Using aerosol remote sensing data collected at Siberian sites of the AErosol RObotic NETwork (AERONET) along with the results of the fourth Fire Lab at Missoula Experiment (FLAME-4), we establish an empirical parameterization relating the ratio of the elemental carbon (EC) and organic carbon (OC) contents in BB aerosol to the ratio of AAOD and AOD at the wavelengths of the satellite observations. Applying this parameterization to the BC and OC column amounts simulated using the CHIMERE chemistry transport model, we optimize the parameters of the BB emission model based on MODIS measurements of the fire radiative power (FRP); we then obtain top-down optimized estimates of the total monthly BB BC amounts emitted from intense Siberian fires that occurred from May to Septem-ber 2012. The top-down estimates are compared to the corresponding values obtained using the Global Fire Emissions Database (GFED4) and the Fire Emission Inventory-northern Eurasia (FEI-NE). Our simulations using the optimized BB aerosol emissions are verified against AAOD and AOD data that were withheld from the estimation procedure. The simulations are further evaluated against in situ EC and OC measurements at the Zotino Tall Tower Observatory (ZOTTO) and also against aircraft aerosol measurement data collected in the framework of the Airborne Extensive Regional Observations in SIBeria (YAK-AEROSIB) Published by Copernicus Publications on behalf of the European Geosciences Union. 14890 I. B. Konovalov et al.: Estimation of black carbon emissions from Siberian fires experiments. We conclude that our BC and OC emission estimates , considered with their confidence intervals, are consistent with the ensemble of the measurement data analyzed in this study. Siberian fires are found to emit 0.41 ± 0.14 Tg of BC over the whole 5-month period considered; this estimate is a factor of 2 larger and a factor of 1.5 smaller than the corresponding estimates based on the GFED4 (0.20 Tg) and FEI-NE (0.61 Tg) data, respectively. Our estimates of monthly BC emissions are also found to be larger than the BC amounts calculated using the GFED4 data and smaller than those calculated using the FEI-NE data for any of the 5 months. Particularly large positive differences of our monthly BC emission estimates with respect to the GFED4 data are found in May and September. This finding indicates that the GFED4 database is likely to strongly underestimate BC emissions from agricultural burns and grass fires in Siberia. All of these differences have important implications for climate change in the Arctic, as it is found that about a quarter of the huge BB BC mass emitted in Siberia during the fire season of 2012 was transported across the polar circle into the Arctic. Overall, the results of our analysis indicate that a combination of the available satellite observations of AAOD and AOD can provide the necessary constraints on BB BC emissions.

[insu-01258732] Overview of the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate (ChArMEx/ADRIMED) summer 2013 campaign

Date: 30 Nov 2022 - 11:22

Desc: The Chemistry-Aerosol Mediterranean Experiment (ChArMEx; http://charmex.lsce.ipsl.fr) is a collaborative research program federating international activities to investigate Mediterranean regional chemistry-climate interactions. A special observing period (SOP-1a) including intensive airborne measurements was performed in the framework of the Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region (ADRIMED) project during the Mediterranean dry season over the western and central Mediterranean basins, with a focus on aerosol-radiation measurements and their modeling. The SOP-1a took place from 11 June to 5 July 2013. Airborne measurements were made by both the ATR-42 and F-20 French research aircraft operated from Sardinia (Italy) and instrumented for in situ and remote-sensing measurements, respectively, and by sounding and drifting balloons, launched in Minorca. The experimental setup also involved several ground-based measurement sites on islands including two ground-based reference stations in Corsica and Lampedusa and secondary monitoring sites in Minorca and Sicily. Additional measurements including lidar profiling were also performed on alert during aircraft operations at EARLINET/ACTRIS stations at Granada and Barcelona in Spain, and in southern Italy. Remote-sensing aerosol products from satellites (MSG/SEVIRI, MODIS) and from the AERONET/PHOTONS network were also used. Dedicated meso-scale and regional modeling experiments were performed in relation to this observational effort. We provide here an overview of the different surface and aircraft observations deployed during the ChArMEx/ADRIMED period and of associated modeling studies together with an analysis of the synoptic conditions that determined the aerosol emission and transport. Meteorological conditions observed during this campaign (moderate temperatures and southern flows) were not favorable to producing high levels of atmospheric pollutants or intense biomass burning events in the region. However, numerous mineral dust plumes were observed during the campaign, with the main sources located in Morocco, Algeria and Tunisia, leading to aerosol optical depth (AOD) values ranging between 0.2 and 0.6 (at 440 nm) over the western and central Mediterranean basins. One important point of this experiment concerns the direct observations of aerosol extinction onboard the ATR-42, using the CAPS system, showing local maxima reaching up to 150 M m−1 within the dust plume. Non-negligible aerosol extinction (about 50 M m−1) has also been observed within the marine boundary layer (MBL). By combining the ATR-42 extinction coefficient observations with absorption and scattering measurements, we performed a complete optical closure revealing excellent agreement with estimated optical properties. This additional information on extinction properties has allowed calculation of the dust single scattering albedo (SSA) with a high level of confidence over the western Mediterranean. Our results show a moderate variability from 0.90 to 1.00 (at 530 nm) for all flights studied compared to that reported in the literature on this optical parameter. Our results underline also a relatively low difference in SSA with values derived near dust sources. In parallel, active remote-sensing observations from the surface and onboard the F-20 aircraft suggest a complex vertical structure of particles and distinct aerosol layers with sea spray and pollution located within the MBL, and mineral dust and/or aged North American smoke particles located above (up to 6–7 km in altitude). Aircraft and balloon-borne observations allow one to investigate the vertical structure of the aerosol size distribution showing particles characterized by a large size (> 10 µm in diameter) within dust plumes. In most of cases, a coarse mode characterized by an effective diameter ranging between 5 and 10 µm, has been detected above the MBL. In terms of shortwave (SW) direct forcing, in situ surface and aircraft observations have been merged and used as inputs in 1-D radiative transfer codes for calculating the aerosol direct radiative forcing (DRF). Results show significant surface SW instantaneous forcing (up to −90 W m−2 at noon). Aircraft observations provide also original estimates of the vertical structure of SW and LW radiative heating revealing significant instantaneous values of about 5° K per day in the solar spectrum (for a solar angle of 30°) within the dust layer. Associated 3-D modeling studies from regional climate (RCM) and chemistry transport (CTM) models indicate a relatively good agreement for simulated AOD compared with observations from the AERONET/PHOTONS network and satellite data, especially for long-range dust transport. Calculations of the 3-D SW (clear-sky) surface DRF indicate an average of about −10 to −20 W m−2 (for the whole period) over the Mediterranean Sea together with maxima (−50 W m−2) over northern Africa. The top of the atmosphere (TOA) DRF is shown to be highly variable within the domain, due to moderate absorbing properties of dust and changes in the surface albedo. Indeed, 3-D simulations indicate negative forcing over the Mediterranean Sea and Europe and positive forcing over northern Africa. Finally, a multi-year simulation, performed for the 2003 to 2009 period and including an ocean–atmosphere (O–A) coupling, underlines the impact of the aerosol direct radiative forcing on the sea surface temperature, O–A fluxes and the hydrological cycle over the Mediterranean.

[hal-01981030] Formation of secondary organic aerosol in the Paris pollution plume and its impact on surrounding regions

Date: 29 Nov 2022 - 14:08

Desc: Secondary pollutants such as ozone, secondary inorganic aerosol, and secondary organic aerosol formed in the plumes of megacities can affect regional air quality. In the framework of the FP7/EU MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation) project, an intensive campaign was launched in the greater Paris region in July 2009. The major objective was to quantify different sources of organic aerosol (OA) within a megacity and in its plume. In this study, we use airborne measurements aboard the French ATR-42 aircraft to evaluate the regional chemistry-transport model CHIMERE within and downwind of the Paris region. Two mechanisms of secondary OA (SOA) formation are used, both including SOA formation from oxidation and chemical aging of primary semivolatile and intermediate volatility organic compounds (SI-SOA) in the volatility basis set (VBS) framework. As for SOA formed from traditional VOC (volatile organic compound) precursors (traditional SOA), one applies chemical aging in the VBS framework adopting different SOA yields for high- and low-NOx environments, while another applies a single-step oxidation scheme without chemical aging. Two emission inventories are used for discussion of emission uncertainties. The slopes of the airborne OA levels versus Ox (i.e., O3 + NO2) show SOA formation normalized with respect to photochemical activity and are used for specific evaluation of the OA scheme in the model. The simulated slopes were overestimated slightly by factors of 1.1, 1.7 and 1.3 with respect to those observed for the three airborne measurements, when the most realistic "high-NOx" yields for traditional SOA formation in the VBS scheme are used in the model. In addition, these slopes are relatively stable from one day to another, which suggests that they are characteristic for the given megacity plume environment. The configuration with increased primary organic aerosol (POA) emissions and with a single-step oxidation scheme of traditional SOA also agrees with the OA / Ox slopes (about ± 50 % with respect to the observed ones); however, it underestimates the background. Both configurations are coherent with observed OA plume buildup, but they show very different SI-SOA and traditional anthropogenic SOA (ASOA) contributions. It is hence concluded that available theoretical knowledge and available data in this study are not sufficient to discern the relative contributions of different types of anthropogenic SOA in the Paris pollution plume, while its sum is correctly simulated. Based on these simulations, for specific plumes, the anthropogenic OA buildup can reach between 8 and 10μg m−3. For the average of the month of July 2009, maximum OA increases due to emissions from the Paris agglomeration are noticed close to the agglomeration at various length scales: several tens (for primary OA) to hundreds (for SI-SOA and ASOA) of kilometers from the Paris agglomeration. In addition, BSOA (SOA formed from biogenic VOC precursors) is an important contributor to regional OA levels (inside and outside the Paris plume)

[hal-01238192] Volatile and Organic Compositions of Sedimentary Rocks in Yellowknife Bay, Gale Crater, Mars

Date: 29 Nov 2022 - 12:12

Desc: H2O, CO2, SO2, O2, H2, H2S, HCl, chlorinated hydrocarbons, NO, and other trace gases were evolved during pyrolysis of two mudstone samples acquired by the Curiosity rover at Yellowknife Bay within Gale crater, Mars. H2O/OH-bearing phases included 2:1 phyllosilicate(s), bassanite, akaganeite, and amorphous materials. Thermal decomposition of carbonates and combustion of organic materials are candidate sources for the CO2. Concurrent evolution of O2 and chlorinated hydrocarbons suggests the presence of oxychlorine phase(s). Sulfides are likely sources for sulfur-bearing species. Higher abundances of chlorinated hydrocarbons in the mudstone compared with Rocknest windblown materials previously analyzed by Curiosity suggest that indigenous martian or meteoritic organic carbon sources may be preserved in the mudstone; however, the carbon source for the chlorinated hydrocarbons is not definitively of martian origin.