Characteristics of Asian Dust Observed From 6-year CALIPSO Lidar Measurements

The Asian dust not only plays an important role in the radiative energy budget and hydrological cycle, but also is critical in global biogeochemical cycle. Knowledge of Asian dust aerosols in different source and long-range transport region is important for estimating their impacts on climate. In this study, we examines the vertical distribution, optical properties of Asian dust over the Taklamakan Desert, Gobi Desert and long-range transported regions using CALIPSO V3 aerosol layers, profiles, vertical feature mask, and cloud layers at a nominal resolution of 5 km along the track and covering a 6-year period from Dec, 2006 to Nov, 2012.

The results show that the Taklimakan and Gobi deserts are two major dust sources in East Asia with much more dust occurring in spring and summer, long-range transport mainly occurring in spring and winter. Vertical distribution of Optical properties of Asian dust aerosol indicate that much more irregular and larger dust aerosols near the surface. The average of dust particular depolarization ratio ranges from 0.25 to 0.35 at Taklamakan, Gobi and long-range transport region for different season. Dust optical properties diminish with distance from sources with different seasonal dependencies. They are indicative of a shift in aerosol bulk properties towards spherical and smaller particle types. Additionally, based on above threshold of layer depolarization ratio of dust and non-dust aerosol over different regions, we derived dust optical depth from CALIOP total backscatter, which is consistent to that from MISR at the Taklamakan desert where dust is dominating aerosol.