Identification of Dust and Ice Cloud Formation from A-Train Datasets

Thursday, 18 December 2014
Daniel S Russell1,2 and Kuo-Nan Liou1,2, (1)Joint Institute for Regional Earth System Science and Engineering, University of California, Los Angeles, CA, United States, (2)Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA, United States
Dust aerosols are effective ice nuclei for clouds and instances of nucleation have been well studied in laboratory experiments. We used CALIOP/CALIPSO, MODIS/Aqua, and CloudSat on the A-Train to find collocated instances of clouds characterized as water by MODIS, but contain ice water as indicated by CloudSat. The vertical profiles of CALIPSO detect the presence of dust and polluted dust near clouds. This study concentrates on high dust aerosol areas including the regions surrounding the Sahara Desert as well as South Asia including the Tibetan Plateau. These cases display the effects of dust acting as ice nuclei in the time frame between MODIS overpass and CloudSat overpass (~45 seconds). Utilizing available datasets, we then carried out radiative transfer calculations to understand spectral radiative forcing differences between water and ice clouds, particularly over snow surfaces at the Tibetan Plateau.