A Study on Clouds, Precipitation and Radiation Response to Aerosols Over Different Parts of Indian Region

Abstract

Atmospheric aerosols are one of the most complex and uncertain constituents due to their significance in governing weather and climate over a particular region besides health impacts. Cloud droplets form in the presence of aerosol particles acting as CCN (Cloud Condensation Nuclei). Aerosol concentration may influence the droplets' number in clouds, associated radiation fluxes, and consequent precipitation. The study presented in this thesis considers satellite-based observations of aerosols and clouds combined with other datasets and WRF-Chem outputs to examine how aerosols influence cloud properties, radiation, and precipitation over different parts of the Indian region. Several aerosols, clouds, and meteorological parameters considered for the study. The primary variables considered for the study include aerosol optical depth (AOD), angstrom exponent (AE), cloud effective radius (CER), cloud fraction (CF), cloud optical depth (COD), cloud top pressure (CTP), cloud water path (CWP), relative humidity (RH), lower-tropospheric stability (LTS), vertical velocity (VV), wind speed (WS), shortwave cloud radiative forcing (SWCRF), longwave cloud radiative forcing (LWCRF), net cloud radiative forcing (NetCRF) and rainfall.
In the pre-monsoon months, AOD was found to be moderate to high over Indo-Gangetic Plains (IGP) and coastal regions and low over central, western, and southern parts of the Indian region. Low to significant values of AOD was seen over some parts of IGP and north-eastern Indian region during post-monsoon and winter, indicating the dominance of anthropogenic production and biomass and fossil fuel burning. The trend analysis implies a significant increase in anthropogenic aerosols over the Indian region during all the seasons...