Abstract:
Sulfur dioxide (SO2) is a chemically active trace gas and one of the major criteria
pollutants. Pakistan lacks the monitoring facility on a larger scale to measure
atmospheric gases on regular bases. This study presents the results of atmospheric
SO2 column densities obtained from satellite observation over Pakistan during the
time period of 2004 – 2012. level-2 data product of satellite instruments
SCIAMACHY onboard ENVISAT, OMI onboard Aura and GOME-2 onboard Metop
retrieved by using Differential optical absorption spectroscopy (DOAS) technique are
used. Spatio-temporal distribution of SO2 column densities along with the seasonal
variation over main cities and regions of Pakistan has been discussed. The Nabro
volcano eruption in 2011 had caused high SO2 columns over East Africa, Middle East
and South Asian regions. Satellite images tracked the transported SO2 pollution over
Pakistan during this event. Other significant volcanic eruptions and their trans
boundary effect over Pakistan’s atmosphere have also been discussed in this study.
Back trajectory analysis is performed to track the origin of air masses with high SO2
column densities detected over Pakistan. Temporal evolution of SO2 column densities
exhibited an overall increase of 70% (125% with fraction of trans-boundary SO2
pollution from regional volcanoes) during the time period of 2004-2012. Spatial and
temporal analyses of SO2 pollution over Pakistan by using satellite observation has
been discussed for the first time in Pakistan.
