An observational study of aerosol optical properties and their relationships with meteorological parameters over Bangladesh

Abstract

Atmospheric aerosol is important element of atmospheric system and became a major uncertainty in global climate simulation. Therefore proper assessment of aerosol is crucial in current climate diagnostic. In this paper the characteristics of aerosol optical depth (AOD), angstrom exponent (AE) and fine mode fraction (FMF) are derived using MODerate resolution Imaging Spectroradiometer (MODIS) remote sensing data over Bangladesh in the last decade. AOD and FMF are increasing across Bangladesh while AE is decreasing. Western part of Bangladesh shows higher AOD along with lower AE and lower FMF. AOD exhibits negative correlations with both AE and FMF. Monthly and seasonal mean variations of AOD, AE and FMF report the highest AOD in pre-monsoon season while highest AE and highest FMF in post-monsoon season. After that the relationships of AOD with meteorological parameters namely rain rate and land surface temperature are analyzed. The rain rate is derived by Tropical Rainfall Measuring Mission (TRMM) remote sensing data over Bangladesh. The results between AOD and meteorological parameters show good relationships. MODIS land surface temperature reveals strong positive correlation with AOD indicating that higher land surface temperature enhances aerosol loading. TRMM rain rate shows negative correlation with AOD referring that higher rain rate weaken aerosol loading and vice versa. However more studies and longer data sets are needed for approving these arguments.