Improving Aerosol Simulation over South Asia for Climate and Air Quality Studies

Abstract:

Atmospheric aerosol over South Asia has attracted increasing concern over the recent decades due to its significant effects on air quality and climate. However the aerosol properties over South Asia has been poorly represented in most global models, with the surface concentrations, aerosol optical depth (AOD), and absorbing AOD (AAOD) significantly underestimated, especially in October-January when the agricultural waste burning and anthropogenic aerosol dominates over dust aerosol. This study investigates the causes for such discrepancy by conducting a series of model sensitivity experiments with NASA’s GEOS-5 model with results evaluated with satellites, AERONET and in-situ measurements. The primary objectives of our research are to examine: 1) whether the aerosol sources (especially anthropogenic) used in the model are underestimated; 2) whether the meteorological conditions (such as relative humidity) are poorly represented in the model; 3) whether the commonly used spatial resolution in the current global models is inadequate to resolve the aerosol distributions features in South Asia. Results from this study will contribute to our understanding of key factors to determine the aerosol distribution over South Asia, and providing insights on improving aerosol representation in global models.