Continuous Monitoring of Ammonia over South Asia Using the Satellite Observations from 2004-11

Abstract

Agricultural activity including the use of nitrogenous fertilizers is known as the major source. Ammonia has a short life time and reacts with other pollutants like the oxides of Sulphur and nitrogen to form fine particulates Because of its toxicity and adverse impacts on the atmosphere, monitoring of ammonia is necessary. Continuous monitoring as well as spatially coherent picture of Ammonia distribution can only be possible through the use of satellite along with extensive ground based observations. In this study, ammonia is mapped over South Asia by using data from NASA’s Aura satellite mission. Tropospheric Emission Spectrometer is the instrument on Aura that monitors Ammonia along with other trace gases. Monitoring is done on monthly basis in order to identify the emission sources of atmospheric ammonia in South Asia. A database of atmospheric ammonia column densities is generated to identify temporal trends, seasonal cycles for the identification of Ammonia hotspots across the South Asian region. Different seasonal cycles were identified for different regions, however the maximum NH3 column densities were observed during the month of July. In an attempt to link ammonia emissions to its sources, the observations were supplemented by fertilizer data obtained from National Fertilizer Development Center, Pakistan. Role of atmospheric parameters (temperature and precipitation) on the ammonia emissions were also explored. Results showed that these factors, individually do not have significant impact. Global emission inventories data sets were also compared for the study region and verified with air column densities. The satellite data shows an under-estimation over the study region. The reasons for this discrepancy are not clear however most of the emission inventories are over estimated.