卫星遥感地面紫外辐射的参数化方法

A Parameterization Method for Retrieving Surface UVB Radiation from Satellite

提出了一个从卫星观测推算地面ＵＶＢ辐射通量密度和红斑生物紫外辐射剂量的 新的参数化方法。该方法基于一个简单的模式：大气辐射传输介质被简化成三个等效层：臭 氧单独构成的吸收层，空气分子、云和气溶胶粒子组成的散射层，以及地面反射层。地面紫 外辐射通量密度和生物紫外辐射剂量可以由臭氧层的等效透过率、散射层和地面的联合反射 率计算。臭氧层的等效透过率可由大气臭氧总量计算。散射层和地面的联合反射率可由不存 在臭氧吸收的紫外或可见光通道的反射辐射强度测量得到。该反演算法形式简单，只包含很 少几个可从卫星测量获得的参数。它通过了一个可靠而相对复杂的基于ＤＩＳＯＲＴ的紫外辐 射传输模式的检验。在广泛的计算条件下，包括晴天、云天、以及混浊大气，用这个简单算 法计算的地面紫外辐射通量密度和红斑生物紫外辐射剂量与精确算法的结果相差无几。另 外，还实际运用这个算法利用卫星观测资料反演地面紫外辐射通量密度，与地面实际观测资 料做了比较，符合较好。

A new parameterization method for retrieving surface UVB irradiance and erythemal UVB radiative dose rate is presented. This method is based on a simple concept: the earth-atmosphere system can be equivalent to three layers: absorption layer by ozone, scattering layer containing air molecules, cloud and aerosol particles, and the surface reflecting. The surface UVB irradiance and erythemal UVB dose rate can be expressed by the effective transmission of the ozone layer and united reflectivity due to the scattering layer and the surface. The effective ozone transmission is calculated from the atmospheric total ozone amount, while the united reflectivity is determined from the satellite measured reflectivity at ozone insensitive ultraviolet or visible band. The retrieval method is simple with some parameters, which can be determined from satellite observations. The comparison of this method with an accurate DISORT-based radiative transfer model has been done. Small differences are shown for wide atmospheric conditions including clear, cloudy sky and turbid atmosphere. An actual application has been Performed using satellite observations, and the results are compared with the surface observations. And the two are in a good agreement.