Distribution, source and transport of the aerosols over Central Asia

Limited by scarce observations, the sources and transport of aerosols over Central Asia are relatively unclear. In this study, using Terra and Aqua satellite images, Moderate Resolution Imaging Spectroradiometer (MODIS) data, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite observations and meteorological reanalyze data, the distribution, source and transport of aerosols over Central Asia are investigated. We find that there are 227 aerosol events occurred in Central Asia during 2000-2017_ and the aerosols which can be transported from outside to Central Asia are dominated by dust and smoke (organic carbon and black carbon) particles. Statistical analyses show that the contribution of the sources outside of Central Asia (76 times) to all aerosol events (122 times) is greater than that of local emissions in Central Asia (46 times) in the spring and summer during 2000-2017. The smoke events (39 times), sourcing from Russia and Europe with strong northwest wind, account for 51.3% of total aerosol events contributed by sources outside of Central Asia. Additionally, the dust events (37 times), which mainly source from the northern Arabia Peninsula and North Africa with strong southwest wind, account for 48.7% of the total aerosol events contributed by the sources outside of Central Asia. On the contrary, the contribution of local emissions in Central Asia (90 times) to all aerosol events (105 times) is greater than that of outside sources (15 times) in the autumn and winter. Result of clustering analyses for all 157 aerosol events during 2005-2017 is in agreement with the conclusion of statistical analyses based on observations. This study can provide some evidence to understand the aerosol properties over the Central Asia.