Characteristics Of Temporal And Spatial Distribution Of Dust Aerosols Over China

CALIPSO observations under cloud-free conditions from June2006to May2012are used to derive dust aerosol distribution over China. It shows that a dust belt is mainly located between38°N-44°N. There is a strong seasonal variation in dust distributions, which is influenced by seasonal wind fields and convection activity over dust sources. Over Taklimakan Desert, dust occurrence frequency and lifting height are largest in Spring and Summer while the frequency and lifting height are smallest in Winter. Over Gobi Desert, dust occurrence frequency and lifting height are largest in Spring while in Winter lifting height is smallest but the frequency in low altitudes is larger than in Summer and Autumn. Over Qaidam Basin, the frequency in Spring and Summer is significantly larger than in Autumn and Winter. Over Eastern North China, except for in Spring the frequency in other seasons is small.CALIPSO has smaller AOD than MODIS and MISR. Dust AOD and OMI AI have the same variation tendency. Dust optical depth over Taklimakan Desert reaches a maximum of0.44in Spring with a peak in April and a minimum of0.17in Winter. Angstrom Index has a negative correlation with AOD. The peaks of extinction coefficient profiles are largest in Spring and Winter and the profiles decrease faster with increasing altitude than in Summer and Autumn. Dust optical depth over Gobi Desert and Qaidam Basin reaches maximum in Spring when Angstrom Index is smallest and has a smooth variation all the year. Over Eastern North China, dust has largest optical depth in Spring and smallest in Summer and largest Angstrom Index in Summer. Dust extinction coefficient is largest in Spring above3.5km and largest in Summer and smallest in Spring under3.5km. Depolarization ratio profiles and color ratio profiles over dust sources decrease with increasing altitude. The depolarization ratio over Taklimakan Desert and Qaidam Basin is between0.2and0.35while0.16-0.3in Gobi Desert, which may indicate that mineral composition of Taklimakan Desert is similar with Qaidam Basin but different with Gobi Desert. The depolarization ratio profiles over Eastern North China increase with increasing altitude because dust aerosols are mixed with other aerosols in low levels. Color ratio over dust sources are larger than Eastern North China and the color ratio of the latter is largest in Spring and smallest in Summer.