Performance of MODIS Deep Blue Collection 6.1 Aerosol Optical Depth Products over Indonesia: Spatio-temporal Variations and Aerosol Types

Aerosols are solid and liquid particles found in the atmosphere and the earth's surface, aerosols on the earth's surface have a negative impact on humans such as respiratory problems and shortening of visibility. Aerosol Robotic Network (AERONET) has provided Aerosol Optical Depth (AOD) ground-based observations, while Moderate Resolution Imaging Spectroradiometer (MODIS) provided for satellite-based observations. In this study, we aimed to evaluate the AOD from MODIS Deep Blue Collection 6.1 data to determine the spatio-temporal variation of AOD and aerosol types in Indonesia. The results indicates that AOD from AERONET and MODIS have a good correlation in Sumatra Island i.e. Kototabang (R = 0.92 p < 0.01 and RMSE = 0.3) and Jambi (R = 0.91, p < 0.01 and RMSE = 0.32) and Kalimantan Island i.e. Palangkaraya (R = 0.92 with p < 0.01 and RMSE = 0.33), and Pontianak (R = 0.95, p < 0.01 and RMSE = 0.16). In general, MODIS AOD data tends to overestimate AOD from AERONET over Indonesia. The temporal variation of AOD between AERONET and MODIS has a similar pattern, as shown by the increase of AOD during the dry season and a decrease in the wet season over Indonesia. The spatial distribution of AOD MODIS DB C6.1 during September-October-November (SON) is higher than during December-January-February (DJF). AOD in western part of Indonesia is higher than the eastern part of Indonesia, which likely due to the industrial area in Indonesia is mostly found in the western region. Bandung and Jambi are areas that have high AODs, while Palu and Sorong are areas that have low AODs. Aerosols types in Indonesia are mostly consisted of clean continental followed by biomass burning/urban-industrial. The highest concentration of clean continental aerosol was found over Palu (87%), while the highest concentration of biomass burning/urban-industrial aerosol was found over Bandung (75%). For mixed aerosols, the highest concentration was found over Pontianak with a concentration value of 47%, while clean maritime and desert dust aerosols were not found at all observation sites.