Improving Our Understanding of Atmospheric Aerosols and Their Climate Effects

This dissertation is a collection of studies focusing on improving our understanding of atmospheric aerosols using both observational data and model simulations. EOF analysis of Aerosol Index (AI) product from Total Ozone Mapping Spectrometer (TOMS) and Ozone Monitoring Instrument (OMI) reveals global distribution of absorbing aerosols, with major sources lying in Sahara deserts, the Sahel region, South America and South Africa. Analysis of aerosol Single Scattering Albedo (SSA) data from AErosol RObotic NETwork (AERONET) further indicate trends in SSA over a number of globally distributed stations, which might be associated with changes in aerosol composition and thus their optical properties. More importantly, the changes in SSA alter the radiative forcing of aerosols. They may also potentially impact satellite retrievals of aerosol properties as generally a constant SSA is assumed in the retrieval algorithms. In order to assess satellite retrieved aerosol optical properties, collocated pixel level Aerosol Optical Depth (AOD) and Ångström Exponent (AE) data from MODerate resolution Imaging Spectroradiometer (MODIS) are compared with AERONET measurements over 10 stations represent