Climatology of fine and coarse mode aerosol optical thickness over East and South Asia derived from POLDER/PARASOL satellite

The climatological characteristics of total aerosol optical thickness (AOT) together with fine and coarse mode AOT (fAOT and cAOT) and fine mode fraction (FMF ¼ fAOT/AOT) over East and South Asia are presented here for the period March 2005 to October 2013. The characteristics are retrieved from POLDER/PARASOL measurements using recently developed aerosol component module of GRASP algorithm. The satellite retrievals were validated and presented a good agreement with the AERONET products (e.g., R of~0.8-0.9 for AOT, fAOT, Angstrom exponent, and FMF). The results show a seasonal cycle and strong relation to the emission sources. For example, FMF has a peak of nearly 1.0 in March in the Indo-China Peninsula region, reaching a minimum of about 0.4 in April in Northwestern China region. These patterns can be explained by dominance of anthropogenic pollution or desert dust emissions. Maps of fine, coarse, and total AOT, as well as of FMF for the East and South Asia region, are presented and analyzed in scope of seasonal and interannual variabilities.