资源环境科技发展态势分析平台

Aerosols affect global as well as regional climate by interacting with solar radiations and by altering the cloud properties. Due to the scarcity of ground observations over entire India, especially over Indo-Gangetic Plains (IGP), satellite-based measurements provide better spatial and temporal coverage for the evaluation of aerosol optical properties. This study presents the inter-comparison of multiple satellites (MISR, MODIS, and OMI) and ground-based aerosol optical depth (AOD) for the 2010-2017 (8 years) period over IGP (Gandhi College, Jaipur, and Kanpur) region. Satellite observations are spatially and temporally collocated by an average of 50 x 50 km square box and +/- 30 minutes, respectively. Results indicate a higher correlation with MODIS (R-2 = 0.7 at Gandhi College) followed by MISR and OMI AOD. Irrespective of few observations (219) at Jaipur, MISR shows the highest percentage (58%) of data points within the error envelope because of multiple angle viewing and spectral capability gives the accurate information in high reflecting desert areas. MISR and OMI have a systematic negative bias trend for higher AOD at all WA sites, while MODIS has a negative bias over the Jaipur region only. The temporal analysis reveals the higher concentration of fine mode aerosols captured by MISR and MODIS in December month over Gandhi College and Kanpur region, whereas Jaipur is over-loading with coarser aerosols during April to June month from the Thar Desert and Middle East dust storms. Seasonal distribution over the IGP region indicates higher AOD in summer owing to dust storms. Inter-comparison shows that MODIS has higher seasonal AOD as compared to MISR. The spatial correlation between MODIS and MISR is high during the summer and winter seasons. The OMI sensor performance over the IGP region has not been found to match with existing patterns. These findings are useful in the context of selecting the most reliable satellite AOD products for future studies.