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Article Dans Une Revue Atmospheric Chemistry and Physics Année : 2014

On the relationship between Arctic ice clouds and polluted air masses over the North Slope of Alaska in April 2008

Jacques Pelon
Eric Girard
Gérard Ancellet
Julien Delanoë
  • Fonction : Auteur

Résumé

Recently, two Types of Ice Clouds (TICs) properties have been characterized using ISDAC airborne measurements (Alaska, April 2008). TIC-2B were characterized by fewer (<10 L−1) and larger (>110 μm) ice crystals, a larger ice supersaturation (>15%) and a fewer ice nuclei (IN) concentration (<2 order of magnitude) when compared to TIC-1/2A. It has been hypothesized that emissions of SO2 may reduce the ice nucleating properties of IN through acidification, resulting to a smaller concentration of larger ice crystals and leading to precipitation (e.g. cloud regime TIC-2B) because of the reduced competition for the same available moisture. Here, the origin of air masses forming the ISDAC TIC-1/2A (1 April 2008) and TIC-2B (15 April 2008) is investigated using trajectory tools and satellite data. Results show that the synoptic conditions favor air masses transport from the three potentials SO2 emission areas to Alaska: eastern China and Siberia where anthropogenic and biomass burning emission respectively are produced and the volcanic region from the Kamchatka/Aleutians. Weather conditions allow the accumulation of pollutants from eastern China/Siberia over Alaska, most probably with the contribution of acid volcanic aerosol during the TIC-2B period. OMI observations reveal that SO2 concentrations in air masses forming the TIC-2B were larger than in air masses forming the TIC-1/2A. Airborne measurements show high acidity near the TIC-2B flight where humidity was low. These results strongly support the hypothesis that acidic coating on IN are at the origin of the formation of TIC-2B.
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Dates et versions

hal-00789168 , version 1 (18-12-2015)

Identifiants

Citer

Caroline Jouan, Jacques Pelon, Eric Girard, Gérard Ancellet, Jean-Pierre Blanchet, et al.. On the relationship between Arctic ice clouds and polluted air masses over the North Slope of Alaska in April 2008. Atmospheric Chemistry and Physics, 2014, 14 (3), pp.1205-1224. ⟨10.5194/acp-14-1205-2014⟩. ⟨hal-00789168⟩
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