Satellite observations of ammonia over South Asia

Abstract Ammonia (NH3) plays an important role in atmospheric chemistry and is one of the key components for aerosol (particulate matter—PM2.5) formation, which can have deleterious effects on the environment and population health locally and regionally. This chapter describes the spatiotemporal variations in atmospheric NH3 concentrations using satellite observations over South Asia. The NH3 hot spots are mainly associated with the major agricultural regions of South Asia. The highest NH3 concentrations are observed over the densely populated Indo-Gangetic Plains (IGP) region, which is the main agricultural region of South Asia. The interannual and seasonal variability in NH3 concentrations are strongly influenced by the changes in meteorology and agricultural practices in the regions. The main agricultural regions of South Asia show a general increase in NH3 concentrations in the study period from 2013 to 2018.