Interactions of Aerosol Optical Depth and Cloud Parameters with Rainfall and the Validation of Satellite Based Rainfall Observations

Aerosol-cloud interactions influence the global precipitation patterns that influence significantly the Earth's climate system. Anthropogenic aerosols alter the clouds and their optical properties. The present study has investigated the Aerosol Optical Depth (AOD), cloud parameters and rainfall interactions for three different monsoon periods (2008-2010) and also compared the satellite rainfall with ground based observations, by using MODIS and TRMM datasets. The highest average of AOD was in the month of June and lowest was in July for both Rajshahi and Sylhet divisions. Comparing between Rajshahi and Sylhet, Rajshahi was in the peak of aerosol contamination than Sylhet. The cloud parameters, such as COD and CER, were positively correlated with rainfall except CER in Rajshahi during the 2010 monsoon season and in Sylhet during the 2008 monsoon season. The investigation has showed complex interaction among AOD, cloud parameters and rainfall in both regions during the study period. In addition TRMM satellite-derived rainfall has compared with ground-measured values. The result indicated that TRMM rainfall data were in good agreement with ground measurements with correlation coefficient of above 0.90 in Rajshahi.