REMOTE SENSING RETRIEVALS FROM SPOT MEASUREMENTS OF AEROSOL OVER PENANG ISLAND, MALAYSIA

摘要

Traditional air pollution monitoring by using ground based instruments cannot provides air pollution over a large spatial scale. Aerosol over Penang Island was mapped with SPOT satellite image in this study. The objective of this study is to evaluate the relationship between SPOT satellite observation and particulate matter of size less than 2.5 micron (PM2.5) parameter. It is based on detection of dark surface targets in the blue band. Only one visible wavelength band were used in this study. The surface reflectance values for the only one visible wavelength were determined based on the information given by using ATCOR2image processing technique. The atmospheric components were then estimated from the image. A total of 25 ground truth PM2.5 data were collected simultaneously with the acquired satellite image by using a hand held DustTrak Meter and their locations were determined using a hand held Global Positioning System (GPS). The digital numbers of the corresponding in situ data were converted into irradiance and then reflectance. The atmospheric reflectance values was extracted from the satellite observation reflectance values subtrated by the amount given by the surface reflectance. The atmospheric reflectance values were later used for PM2.5 mapping using the calibrated algorithm. An algorithm was developed based on the atmospheric optical characteristic. The developed algorithm was used to correlate the digital signal and the PM2.5 concentration. A good linear correlation between the satellite signal and PM2.5 parameter was found in this study (R > 0.8). Finally, a PM2.5 map was generated using the proposed algorithm. This study indicates that the feasibility of using the visible band from SPOT for PM2.5 mapping.