利用MODIS资料反演杭州市500米分辨率气溶胶光学厚度

Retrieval of 500m Spatial Resolution Aerosol Optical Thickness with MODIS Data over Hangzhou

反演城市/区域范围内高空间分辨率的气溶胶光学厚度时,如果气溶胶类型选取的不合理造成的反演误差会很大,甚至超过地表反射率确定误差导致的反演误差。针对这一问题,本文提出了一种结合MODIS L1B资料和AERONET(Aerosol Robotic Network)的气溶胶光学厚度产品,基于6S大气辐射传输模型的计算,确定杭州市在2008年12月16日的气溶胶类型的方法。利用得到的气溶胶类型,结合改进的暗像元法,反演了杭州市500m空间分辨率的气溶胶光学厚度。将气溶胶光学厚度反演结果与采用标准气溶胶类型时的反演结果进行比较,结果表明,本文确定的气溶胶类型更符合杭州市当天的情况,应用到气溶胶光学厚度反演中,精度也最好,相对误差的绝对值在20%以内。

The unreasonable selection of aerosol model may cause significant error in retrieving of urban/local scale aerosol optical thickness of high spatial resolution.The error may even be higher than that caused by the surface reflectance uncertainty.For this problem,a method is proposed here to determine the aerosol type of Hangzhou city on December 16,2008.The method is realized by combination of MODIS L1B data and Aerosol Robotic Network（AERONET） products of aerosol optical thickness as well as the calculation of 6S atmospheric radiative transfer model.The 500 m spatial resolution AOT over Hangzhou is estimated utilizing the aerosol type determined by above stated model and Dark Dense Vegetation（DDV） method.The retrieved AOT is compared with that obtained using the standard aerosol type.The comparison results show that the determined aerosol type in this paper is more in consistent with the situation of Hangzhou city on that day.Hence,when it is applied to retrieve aerosol optical thickness,the retrieval accuracy is also the best,which is within ±20%.