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© 2018. This work is published under https://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.

Abstract

Mineral dust from arid areas is a major component of global aerosol and has strong interactions with climate and biogeochemistry. As part of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx) to investigate atmospheric chemistry and its impacts in the Mediterranean region, an intensive field campaign was performed from mid-June to early August 2013 in the western basin including in situ balloon-borne aerosol measurements with the light optical aerosol counter (LOAC). LOAC is a counter/sizer that provides the aerosol concentrations in 19 size classes between 0.2 and 100 µm, and an indication of the nature of the particles based on dual-angle scattering measurements. A total of 27 LOAC flights were conducted mainly from Minorca Island (Balearic Islands, Spain) but also from Ile du Levant off Hyères city (SE France) under 17 light dilatable balloons (meteorological sounding balloons) and 10 boundary layer pressurised balloons (quasi-Lagrangian balloons). The purpose was to document the vertical extent of the plume and the time evolution of the concentrations at constant altitude (air density) by in situ observations. LOAC measurements are in agreement with ground-based measurements (lidar, photometer), aircraft measurements (counters), and satellite measurements (CALIOP) in the case of fair spatial and temporal coincidences. LOAC has often detected three modes in the dust particle volume size distributions fitted by lognormal laws at roughly 0.2, 4 and 30 µm in modal diameter. Thanks to the high sensitivity of LOAC, particles larger than 40 µm were observed, with concentrations up to about 10-4 cm-3. Such large particles were lifted several days before and their persistence after transport over long distances is in conflict with calculations of dust sedimentation. We did not observe any significant evolution of the size distribution during the transport from quasi-Lagrangian flights, even for the longest ones ( 1 day). Finally, the presence of charged particles is inferred from the LOAC measurements and we speculate that electrical forces might counteract gravitational settling of the coarse particles.

Details

Title
In situ measurements of desert dust particles above the western Mediterranean Sea with the balloon-borne Light Optical Aerosol Counter/sizer (LOAC) during the ChArMEx campaign of summer 2013
Author
Renard, Jean-Baptiste 1 ; Dulac, François 2 ; Durand, Pierre 3 ; Bourgeois, Quentin 4 ; Denjean, Cyrielle 5 ; Vignelles, Damien 1 ; Couté, Benoit 1 ; Jeannot, Matthieu 6 ; Verdier, Nicolas 7 ; Mallet, Marc 8 

 Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), UMR CNRS-Université d'Orléans, 3A avenue de la recherche scientifique, Orléans, France 
 Laboratoire des Sciences du Climat et de l'Environnement (LSCE), UMR CEA-CNRS-UVSQ, IPSL, Université Paris-Saclay, CEA Saclay 701, Gif-sur-Yvette, France 
 Laboratoire d'Aérologie, Université de Toulouse, CNRS, UT3, Toulouse, France 
 Department of Meteorology and Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden 
 Centre National d'Etudes Spatiales (CNES), 18 Avenue Edouard Belin, Toulouse, France; now at: Centre National de Recherches Météorologiques (CNRM), UMR 3589 Météo-France-CNRS, OMP, Météo-France, Toulouse, France 
 Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), UMR CNRS-Université d'Orléans, 3A avenue de la recherche scientifique, Orléans, France; now at: MeteoModem company, Chemin du Moulin, Ury, France 
 Centre National d'Etudes Spatiales (CNES), 18 Avenue Edouard Belin, Toulouse, France 
 Laboratoire d'Aérologie, Université de Toulouse, CNRS, UT3, Toulouse, France; now at: Centre National de Recherches Météorologiques (CNRM), UMR 3589 Météo-France-CNRS, OMP, Météo-France, Toulouse, France 
Pages
3677-3699
Publication year
2018
Publication date
2018
Publisher
Copernicus GmbH
ISSN
16807316
e-ISSN
16807324
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2167586261
Copyright
© 2018. This work is published under https://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.