Characteristics of aerosol transport and distribution in East Asia

We used daily aerosol simulations for the period from 2001 to 2003 that were generated by the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model to characterize aerosol transport and distributions in East Asia. In comparison with the AERONET, MODIS, and visibility observations, the model can capture the main distribution features of the aerosol optical depth (AOD) and its temporal changes with a correlation coefficient of 0.75 and 0.85, respectively. It was found that high AODs occur in Central China, the Sichuan basin, the Indo-China peninsula, the Indian subcontinent, and the Bay of Bengal because of black carbon, organic matter, and sulfate, whereas in the Taklimakan desert and its adjacent regions, high AODs occur because of dust. The potential effects of the hygroscopicity of aerosol particles on the AOD were mainly observed in the Sichuan basin, the Bay of Bengal, the Indo-China peninsula, and Central and Southern China. The East Asian aerosol transport was distinctly affected by the flux divergence induced by aerosol advection (AFD) and by the flux divergence induced by wind divergence/convergence (WFD). For black carbon, organic matter, and sulfate, the effect of AFD was a factor of 2 or 3 larger than that of WFD in the divergence region, whereas AFD dropped to 70% of WFD in the convergence region. The high AOD of black carbon, organic matter, and sulfate over the Sichuan basin related to the circulation characteristics of convergence in low altitudes and divergence in high altitudes, which can collect aerosol from adjacent regions at altitudes below 300 hPa and cause them to diverge easterly at higher altitudes.