Satellite-based Assessment of Air Quality in Megacities

Aerosol products routinely derived from NASA EOS satellites provide an unprecedented opportunity to monitor air pollution around the globe. In this study, aerosol optical thickness and size information retrieved from MODIS instruments on Terra and Aqua satellites are used to examine the air quality over the world's megacities. Aerosol optical thickness is a column-integrated quantity. It reflects not only the aerosol information at the surface but also the total burden of aerosol mass in the atmosphere. Together with retrieved size information, MODIS aerosol optical thickness products have tremendous potential for the assessment of particulate matter emissions from megacities. Comparisons with ground-based PM_2.5 data collected in several megacities and ambient extinction coefficient data measured from the United States Interagency Monitoring of Protected Visual Environments (IMPROVE) network will be presented. Seasonal and annual variations of air pollution over numerous megacities and their relation to population and energy utility efficiency will also be discussed.