Spatio-Temporal Analyses of Atmospheric Sulfur Dioxide Column Densities over Pakistan by Using SCIAMACHY Data

摘要

This paper presents the results of atmospheric Sulfur dioxide (SO2) column densities obtained from satellite observation over Pakistan during the time period of 2004–2012. The level-2 data product of the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instrument on-board ENVISAT-1 is used. SO2 column densities are retrieved by applying differential optical absorption spectroscopy (DOAS) technique. The spatio-temporal distribution of SO2 column densities along with the seasonal variation over main cities and regions of Pakistan are discussed. The Nabro volcano eruption in the year 2011 caused high SO2 levels over East Africa, the Middle East and South and Southeast Asia. Satellite images exhibited several episodes of volcanic SO2 column densities transported to Pakistan. The temporal trend in SO2 column densities was calculated, and the significance of the data set was tested with statistical analysis. An overall increase of about 70% (8.7% per year) in SO2 column densities over Pakistan during the time period of 2004–2012 has been calculated. This study presents the first spatial and temporal analyses of SO2 column densities over Pakistan by using satellite observation.