Surface PM2.5 estimate using satellite-derived aerosol optical depth over India

Concentrations of fine particulate matter (PM2.5) that exceed air quality standards affect human health and have an impact on the earth's radiation budget. The lack of round the clock ground-based observations from a dense network of air quality stations inhibits the understanding of PM2.5's spatio-temporal variability and the assessment of its health and climate effects. Aerosol optical depth (AOD) values retrieved from satellite based instruments can be used to derive surface PM2.5 concentrations. This study integrates Moderate Resolution Imaging Spectroradiometer (MODIS) AOD retrievals and simulations from the Weather Research and Forecasting Model coupled with Chemistry (WRF-Chem) to determine the ground-level PM2.5 concentrations at a 36 km resolution across India. WRF-Chem simulations provide the factor relating the AOD with the PM2.5. Satellite-derived PM2.5 mass concentrations are compared with the available ground-based observations across India for the year of 2011. The results show a correlation between the satellite-derived monthly PM2.5 estimates and the ground-based observations for 15 stations in India with coefficients of 77% and diurnal scale coefficients varying from 0.45 to 0.75. The best estimations of PM2.5 mass concentrations on a spatio-temporal scale across India address various environmental issues.