Atmos. Chem. Phys. Discuss., 13, 4331-4389, 2013
www.atmos-chem-phys-discuss.net/13/4331/2013/
doi:10.5194/acpd-13-4331-2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
On the relationship between Arctic ice clouds and polluted air masses over the north slope of Alaska in April 2008
C. Jouan1,2, J. Pelon2, E. Girard1, G. Ancellet2, J. P. Blanchet1, and J. Delanoë3
1ESCER Centre, Department of Earth and Atmospheric Sciences, University of Quebec at Montreal, H3C 3P8, Montreal, Quebec, Canada
2Laboratoire Atmosphère, Milieux et Observations Spatiales, UMR8190, UPMC, 75252, Paris, France
3Laboratoire Atmosphère, Milieux et Observations Spatiales, UVSQ, 78035, Guyancourt, France

Abstract. Recently, two Types of Ice Clouds (TICs) properties have been characterized using ISDAC airborne measurements (Alaska, April 2008). TIC-2B were characterized by fewer (<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.


Citation: Jouan, C., Pelon, J., Girard, E., Ancellet, G., Blanchet, J. P., and Delanoë, J.: On the relationship between Arctic ice clouds and polluted air masses over the north slope of Alaska in April 2008, Atmos. Chem. Phys. Discuss., 13, 4331-4389, doi:10.5194/acpd-13-4331-2013, 2013.
 
Search ACPD
Discussion Paper
    XML
    Citation
    Final Revised Paper
    Share