Spatio–temporal distribution of absorbing aerosols over Pakistan retrieved from OMI onboard Aura satellite

The observations of aerosol index (AI) deduced from Ozone Monitoring Instrument (OMI) with spatial resolution of 0.25°x0.25° have been analyzed over Pakistan from December 2004 to November 2008. Significant spatio–temporal variabilities in AI values were observed with higher values in southern parts and lower values in northern parts of Pakistan. The mean annual AI in Southern and Northern Pakistan have been found to be 1.220±0.250 and 1.088±0.280, respectively with an overall mean of 1.155±0.257 over the entire country. The monthly spatially averaged values of AI show a clear maximum in the month of May (1.539±0.499), one of the two months having highest dust storm activity in the region, and minimum value in the month of December (0.851±0.134), having lowest dust storm activity. We have also examined the effect of precipitation on AI values and have found that inverse correlation exists between AI and accumulated precipitation, particularly in the months of July, August and September with corresponding R2 values of 0.24, 0.25 and 0.33 respectively.