Numerical study of the dust distribution, source and sink, and transport features over East Asia

The spatial and temporal distribution, production and deposition, and regional transport of mineral dust aerosol over East Asia were quantified by using the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model. Model results showed that the Takalamakan Desert, the Hexi Corridor, and the Hetao Area were the main dust source regions in China. The dust production was largest in spring, relatively small in summer and autumn, and reached its minimum value in winter. Moreover, the dust production was gradually decreased year by year. The annual mean of regional dust emission was predicted to be 581Tg/a. In general, the modeled dust aerosol optical depth (AOD) agreed well with the satellite observations spatially and temporally. Specifically, the high AOD in the Takalamakan Desert was notably influenced by the dust storm activities, in which AOD reached its peaks earlier in a year and kept longer compared with other sources. On the annual mean of regional basis, the dry and wet depositions could remove 77% and 22% of the total dust production, respectively. The dry deposition was the dominate dust removal process over dust sources, while the wet deposition was more important when dust was transported to northeastern China and the northwestern Pacific oceans. Furthermore, the removal process of coarse mode dust was mainly determined by gravitational dry deposition, in contrast, the wet deposition contributed to more than 60% of the removal process of accumulate mode dust. As the most important component, the gravitational dry deposition dominated the dust removal process throughout the year, especially in spring, while the wet deposition from convective precipitation could not be neglected in summer. Similar to dust production, the dust deposition also showed a decreasing trend over the simulation period. There were three major dust transport routes in East Asia, by which the dust aerosol could be transported from the dust source regions to northern, central, and southern China. In addition, the dust divergence region due to aerosol advection term was mainly located over the dust source regions, suggesting that the local heavy dust emission had great impacts on the dust transport and the high AOD there. On the other hand, the dust convergence in the western Tarim Basin induced by wind divergence convergence term indicated that the wind and topography were important for the high dust AOD there. © 2017, Editorial Board of China Environmental Science. All right reserved.