本研究旨在利用MODIS衛星酬載與太陽光度計於2002-2008年間所觀測之氣膠輻射參數，對東南亞地區常見的氣膠種類進行辨識，研究範圍內的空氣污染源主要來自於沙塵暴、生質燃燒與人為污染。藉由收集並分析各AERONET測站所觀測的資料，發現粒徑較大的沙塵氣膠其A ̇ngstro ̈m exponent的觀測值(0.055)遠小於煙塵與都會氣膠，可用於沙塵氣膠之辨識。而在單次散射反照率方面，煙塵氣膠則具有最小值(0.91)，相較於沙塵氣膠與都會氣膠，煙塵氣膠具有較強的吸收能力。因此，結合A ̇ngstro ̈m exponent和單次散射反照率可用來辨識出沙塵、煙塵和都市人為污染等氣膠種類。 然而MODIS的氣膠產品卻不能在低反射率地區完整地提供單次散射反照率參數，故本研究將藉由探討輻射參數間之相關性，估算研究區域的單次散射反照率或散射相位函數。由研究結果顯示，散射角介於8~15度與53~97度之間可用A ̇ngstro ̈m exponent來擬合散射相位函數。因此，本研究進一步分析在特定散射角度的相位函數應用於氣膠種類之辨識，並探討由相位函數值來辨別煙塵氣膠與都會氣膠的可行性。由統計的結果顯示在散射角在8-15間，都會氣膠的相位函數值高於煙塵氣膠， 而在50-90度之間則反之。根據此一特性即可透過衛星觀測資料應用於煙塵氣膠與都會氣膠之辨識。The purpose of this study is to discriminate different types of aerosol over Southeast Asia by the data from MODIS instrument and AERONET during the year of 2002 to 2008. Particles of dust, smoke and pollutants(anthropogenic) are selected as the target types of aerosol in this study. Base on the measurement of AERONET station during the occurrence of dust storm and biomass burning, the Ångström exponent (AE) of dust is about 0.054 which is smaller than smoke and man-made pollutants, indicating the radius of dust is the biggest among the three. With the strong absorption characteristic of smoke, the Single scattering albedo (SSA) of smoke (0.91) is the smallest of these types. Therefore, it is appropriate to use AE and SSA for the discrimination of aerosol types. However the SSA cannot be provided by MODIS in low-reflectivity regions, thus this study will explore the relationship between these aerosol parameters to retrieve SSA and phase function. According to the linear relationship with AE, the phase function can be calculated by AE in specific scattering angle (e.q., 8-15 degrees and 53-97 degrees). Therefore, the discrimination of aerosol types by phase function will be analyzed in this study, and to explore the feasibility of using phase function to recognize smoke and man-made pollutants. The results show that the phase function of man-pollutants is bigger than smoke’s from 8-15 degrees, and smaller than smoke’s from 50-90 degrees. According to the result, it is appropriate to apply the phase function retrieved by MODIS for the discrimination between smoke and man-made pollutants.
