Investigation of permanent aerosol source regions over Asia using multi-year MODIS observations

Abstract

This work examines the permanent aerosol source regions over Asia by analyzing 7-years data of aerosol optical thickness (AOT) product from MODerate Imaging Spectroradiometer (MODIS) onboard Aqua and Terra satellites. The analysis is carried out by taking the average AOT map during the years 2002-2008 over the region in different seasons, in which the permanent source regions will appear pronounced whereas the locations influenced by transport or any emissions that last for shorter time period will be smoothened. The results show four such main permanent source regions. Angstrom Exponent (AE) aerosol product is used to infer about the possible type and size of aerosols over the source regions. The average AOT trends over the source regions in different seasons during 2002-2008 are examined and the results are discussed based on the corresponding variations of meteorological parameters derived from National Center for Environmental Prediction - National Center for Atmospheric Research (NCEP-NCAR) reanalysis data. In addition, the trends in AOT variation during the period 2002-2008 over certain selected stations over the area are also discussed.