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

ABSTRACT

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.