A-Train satellite measurements of dust aerosol distributions over northern China

Horizontal and vertical distributions of dust aerosols over northern China were investigated for the period June 2006 to May 2011 using A-Train satellite constellation data and ground-based measurements. Surface observations at 675 meteorological stations showed that dust events occurred most frequently in the Taklamakan and Gobi deserts. In the Taklamakan Desert, the dust aerosol content was high throughout the year, as seen from the distributions of the Moderate-Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) and the Ozone Monitoring Instrument (OMI) UV-absorption aerosol index (AAI). In the Taklamakan and Gobi deserts, the AOD and AAI reached maxima in spring and minima in winter. In the eastern part of northern China, AOD reached a maximum in summer and a minimum in fall, whereas AAI was high in winter and spring and low in summer and fall due to seasonal differences in the main aerosol type. The dust observations revealed strong seasonal variations in dust coverage area and height, with maxima in spring and summer and minima in fall and winter. The transportation of dust aerosols in all seasons was confined largely between 35 degrees N and 45 degrees N. The mean height of the dust layer top varied and showed strong seasonal variation in all regions, with values higher than 4 km in spring and about 2 km in winter. The Taklamakan Desert experienced higher occurrence of dust events than other regions throughout the year. Dust occurrence decreased dramatically over the eastern part of northern China in summer because of surface vegetation and precipitation. Simulation results by the HYSPLIT model were similar to the distribution of dust aerosols observed by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) during the same period. (C) 2012 Elsevier Ltd. All rights reserved.