Recent advances in remote sensing have provided new avenues for measuring, monitoring, and understanding processes that lead to atmospheric pollution. Space-based measurements in combination with ground-based information provide the complete spatial and temporal variation, as well as regional and global distribution of air pollutants. The present study involves integration of satellite and ground-based measurements and back trajectory analysis concerning the transport of pollutants from different sources. Satellite-derived aerosol optical depth (AOD) represents integrated atmospheric columnar loading of aerosols and can be used as a substitute to assess surface particulate matter air quality, especially where surface measurements are not available. This study is based on investigation of seasonal and spatial variation of aerosol concentration over Karachi, Pakistan using satellite-based AOD data from moderate resolution imaging spectroradiometer on board Terra/Aqua Satellites, ground-based data of two sun-photometers (NASA's AERONET) and other in situ measurements using DustTrak Particulate Monitor at Karachi (24.87° N, 67.03° E), Pakistan.