氣膠光學厚度（Aerosol Optical Depth, AOD）對於空氣品質的監測是極為重要的參考指標，尤其在高時間解析度的提供，而新一代的地球同步衛星Himawari-8（H-8）具有16個可見光和紅外光波段，每10分鐘高時間解析度的1公里空間解析度觀測資料，對於高時、空變化的空氣污染之監測應用相當適合。本研究因此開發同時輻射率定法（Simultaneous Radiation Solution，SRS），配合穿透率轉換查找表以及輻射傳輸模式(Second Simulation of a Satellite Signal in the Satellite Spectrum，6S），解析大氣穿透率和路徑輻射（Path radiance），並根據其結果反演AOD和單次散射反照率（Single Scattering Albedo，SSA)氣膠參數。經Moderate Resolution Imaging Spectroradiometer (MODIS) 衛星產品之測試以及地面觀測資料（AERONET）之驗證，結果顯示此反演方法具有相當高之可行性。 同時輻射率定法在H-8之AOD反演結果與MODIS AOD之空間分布相當一致，且H-8 SSA與AErosol RObotic NETwork （AERONET)比較亦具相當之合理性與準確性。此外，在反演結果的差異分析上則顯示地表反射資料庫建立之重要性，因此本研究亦測試MODIS 8-day地表資料產品之可行性，測試結果與AERONET地面測站之觀測資料相當接近，尤其是嘉義測站，其AOD誤差從原先-43%大幅縮小至-4%。 然而MODIS一天僅2次觀測資料，因此後續將以MODIS地表反射資料配合Himawari-8觀測時序的地表變化特性(雙向反射)，建立適合之H-8地表反射率資料庫，以提升氣膠光學厚度之準確度，期望能提供更準確及大範圍高時間解析度的空氣品質監測資料。 ;Aerosol optical depth (AOD) is one of the important indexes for air quality monitoring, in particular the time series. The new generation geostationary satellite, Himawari-8 (H-8), can provide 3 visible bands, 3 near infrared bands and 10 infrared bands with 0.5 km to 2 km spatial resolution every 10 minutes. The characteristics of multi-spectral bands and highly frequent observations are really suitable for the large scale air quality monitoring. For this purpose, Simultaneous Radiation Solution (SRS) is proposed to derive atmospheric transmittance and path radiance associated with the pre-constructed look-up-table (from Second Simulation of a Satellite Signal in the Satellite Spectrum model, 6S) for H-8 AOD and SSA (single scattering albedo) retrievals. In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) products are employed to examine the practicality of SRS approach. The H-8 AOD retrievals show the similar pattern of spatial distribution with MODIS AOD products. However, the values compared to Aerosol Robotic Network (AERONET) observations are underestimated or overestimated, due to the uncertainties of H-8 surface reflectance database. Therefore, MODIS surface products are applied to H-8 AOD retrievals. Overall, the AOD spatial distribution and magnitudes are well consistent with MODIS product and AERONET observations. The relative error of AOD reduced from -43% to -4% when compared to the AERONET site at Chiayi station. Highly practical in retrieving AOD is suggested by the case study of MODIS. For time series air quality monitoring, the diurnal database of H-8 surface reflectance will be constructed based on MODIS products for highly temporal AOD observation in next step.
