香港及珠三角地区MODIS高分辨率气溶胶光学厚度的反演

Retrieval of aerosol optical thickness over Hong Kong and Pearl River Delta region using MODIS satellite data

为了有效解决地区性和城市范围内的气溶胶分布并反演陆地上气溶胶的性质,一种针对中分辨率成像光谱辐射计(MODIS)的气溶胶反演新算法应运而生.本文首先通过改良的最小反射率技术(MRT)来确定季节性的地表反射率和利用瑞利通道辐射率中解析出大气上气溶胶的反射率来估计气溶胶的反射系数.结果表明,MRT地表反射率的图像和MODIS地表反射系数的产品(MOD09)有很好的契合度,两者的相关系数高达0.9.此外,考虑到不同气溶胶的光学性质和太阳观测组合对计算辐射传输的影响,本研究还制定了全面广泛的差算表(LUT).由此产生的卫星500m分辨率的气溶胶光学厚度(AOT)和香港太阳光度计(AERONET)及MicrotopsII观测资料的相关系数r分别为0.96和0.87(相伴概率值p<0.0001).该研究证明了城区高分辨率气溶胶反演的可行性,还能帮助研究气溶胶的分布和城区大气瞬态污染的影响.此外,MODIS500m分辨率的气溶胶光学厚度图像还可用于研究跨境气溶胶,使定位珠江三角洲区域污染源变得可行.

Aerosol retrieval algorithms for the MODerate Resolution Imaging Spectroradiometer （MODIS） satellite have been developed to estimate aerosol and microphysical properties of the atmosphere which help to address aerosol climatic issues at global scale. However, higher spatial resolution aerosol products for urban areas have not been well researched. In this study, a new aerosol retrieval algorithm for the MODIS 500m resolution data has been developed to retrieve aerosol properties over complex land, which helps to address the aerosol climatic issues for both local and regional areas. The results show that 500m Aerosol Optical Thickness （AOT） data from MODIS are highly correlated （r = 0.96 and r = 0.87 ） with AERONET and MicrotopsII sunphotometer observations in Hong Kong. This study demonstrates the feasibility of aerosol retrieval at ＂fine＂ resolution in urban areas, which can help study aerosol distribution and pinpoint pollution sources.