高分五号卫星偏振遥感陆地上空气溶胶光学厚度

Inversion of aerosol optical depth over land from directionalpolarimetric camera onboard chinese Gaofen-5 satellite

针对多角度偏振成像仪(Directional Polarimetric Camera,DPC)数据,提出了基于多角度多光谱偏振信息的气溶胶光学厚度反演方法。该方法使用Nadal-Breon半经验模型计算地表偏振反射率,以扣除地表影响;采用倍加累加法矢量辐射传输模型构建气溶胶参数查找表,通过计算最小残差,动态确定最优气溶胶模型,从而实现陆地上空气溶胶光学厚度的反演。使用DPC的L1级条带数据,反演获得了中国东部地区气溶胶光学厚度的空间分布,并与MODIS产品和AERONET地基站点数据分别进行了对比,反演结果与MODIS气溶胶产品的整体分布具有很好的一致性;同时,与AERONET地基站点观测结果具有较高的相关性,670 nm和865 nm两个波段的相关系数都在0.8以上,说明该算法模型反演陆地上空的气溶胶光学厚度准确可靠,可为DPC遥感大气气溶胶提供技术支持。

Directional polarimetric camera(DPC)can acquire multi-spectral,multi-angle,radiometric and polarimetric reflectance data from the earth.A method for the inversion of aerosol optical depth was presented according to the multi-spectral,multi-angle and polarimetric data.Firstly,the polarized land surface reflectance is calculated using the Nadal-Breon semi-empirical model to deduct the land surface radiation from the measured value.Secondly,the vector radiation transfer model derived from double-accumulation method is used to construct the lookup table of aerosol optical parameters.Then,the minimum residual is calculated to determine the aerosol model dynamically for the retrieving of aerosol optical thickness over the land.Using the L1 products of DPC,the aerosol optical thickness in eastern China is retrieved.The values are compared with the product of MODIS and the data measured at the same time from AERONET ground station displaced at several places.Results show that the distribution of aerosol optical thickness retrieved from DPC data is in good agreement with MODIS aerosol product.And also,the results of DPC and AERONET ground station are highly correlated.The correlation coefficients of 670 nm and 865nm bands are above 0.8.It demonstrates the feasibility of the algorithm and what we have considered over land.