Remote Sensing Of Aerosols Over Urban Areas

Dense Dark Vegetation algorithms (DDV) can be effectively used to inverse aerosol optical thickness (AOT) over dense vegetation areas. For the urban areas, if the spatial resolution of satellite data is higher, leisure parks and lawns between buildings can acted as dense vegetation pixies, which are suit for AOT inversion with DDV algorithms, but if the spatial resolution of satellite data is lower, it is difficult to find pixels that can be considered as DDV areas, so the DDV algorithms can not well be used in urban areas. The contrast reduction algorithm which based on atmospheric transmittivity can be applied to derive AOT over bright surface, and can be expected to resolve the problems of urban AOT inversion. But in urban areas, for the surface structure is very complex, the characteristics of BRDF (Bi-directional Reflectance Distribution Function) is obvious. So, it is serious challenges to use the contrast reduction algorithm to inverse AOT in urban areas accuratelyThe aim of my study is to to explore the methods of retrieving aerosols in urban areas. Two kinds of satellite data are used to retrieve aerosols in this paper, one is MODIS data, an in-orbit operations moderate resolution imaging spectrometer (MODIS) with 36 channels, and spatial resolutions 250 meters, 500 meters and 1000 meters; the other is the HJ-1 high-spectral imaging spectrometer loaded by the HJ-1 satellite to be launched in 2007, with about 135 channels and a spatial resolution of 100 meters.According to the spatial resolution of MODIS data, in this paper, the contrast reduction algorithm is used to inverse AOT in urban areas with MODIS data. To reduce the affection of BRDF in AOT retrieving with contrast reduction algorithm, the BRDF model for urban areas is developed and applied in AOT inversing in Beijing. During BRDF model constructing in urban areas, two important factors are vegetation covered in urban areas and the geometry structure of the urban. To perform accurate inverse...