Retrieving the composition and concentration of aerosols over the Indo-Gangetic basin using CALIOP and AERONET data

Most GCMs (General Circulation Models) fail to reproduce the AOD (aerosol optical depth) peak over the Indo-Gangetic basin (IGB) as noticed through satellite observations. Insufficient data on aerosol composition makes it difficult to improve GCM results over this source region. In this work, we retrieve the composition and concentration of aerosols over the IGB region, to a first order approximation, by combining the spectral measurements of AOD, single scattering albedo and size distribution available from AERONET (Aerosol Robotic Network) and the extinction profile of aerosols from CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization). Comparison of our results with AM2 (Atmospheric GCM) simulations reveal that AM2 is largely underestimating organics and black carbon concentrations over this region during all months. Sulfate is also underestimated during most months but, there is an overestimation from May to September. There is a compelling need for improving the aerosol inventories and dust sources over the region in order to make realistic assessment of the impacts of aerosols on the south Asian monsoon.