Exploring model representation of aerosol pollution over India using airborne observations, surface measurements and remote sensing

Abstract:

The Indian subcontinent is subjected to some of the highest levels of ambient air pollution in the world, with over 99% of the population living in areas that exceed the World Health Organization guidelines for fine particulate matter. While much attention has been paid to urban emissions of particulate pollution, recent research has demonstrated that a significant fraction of the total aerosol burden is secondary and regional in nature. In addition, health impact assessments for PM2.5 in India are largely based on models that have not been evaluated against in situ measurements. Evaluating and improving model representation of the regional sources and atmospheric fates of ambient aerosol species over the subcontinent is thus of paramount importance. We use airborne Aerosol Mass Spectrometer measurements from the recent SWAAMI campaign in conjunction with satellite observations of aerosols and gas phase precursors (from the MODIS, CALIOP, CrIS and TROPOMI platforms) and surface observations of fine particulate to evaluate and constrain model simulations of various aerosol species over the Indian subcontinent using the GEOS-Chem chemical transport model. We compare multiple anthropogenic emissions inventories over the region to further inform our understanding of emissions uncertainties and also incorporate changes to the wet and dry deposition schemes to study model sensitivities to this process and improve performance over the region. Based on a suite of model evaluation and optimization activities, we develop a comprehensive national‐level source‐sector characterization of aerosol pollution in India.