计算非均一大气条件下太阳辐射通量的一个简单而又精确的模式

发展了一个计算非均一大气条件下太阳辐射通量的一个简单而又精确的模式，其中包括关于大气球反射率与透过率的一个参数化表达式，并引入加权一次散射反照率和加权不对称因子，用于拟合非均一大气条件下计算辐射通量的四个经验订正因子。对清洁和浑浊的两类大气，都具有120060组的辐射通量模拟试验，以检验本模式的精度。这些模拟试验覆盖0－50的云光学厚度、0－0．8地表反射率、Junge和对数正态的气溶胶谱分布、－0．05气溶胶折射率虚部。在均一大气条件下，由本模式计算的120060组向上通量的标准差对清洁和浑浊两类大气分别为1．08％和1．04％；而向下通量的标准差分别为4.12%和3．31％。在非均一大气条件下，由本模式计算的向上通量的标准差对清洁和浑浊两类大气分别为3．01％和3．48％；而向下通量的标准差分别为4．54％和4．89％，其精度远优于均一假设下的计算结果。

A Simple Yet More Accurate Model to Calculate Solar Radiative Flux in the Inhomogeneous Atmosphere

A simple yet more accurate semiempirical model is developed to calculate solar radiative flux in the optically inhomogeneous atmosphere. In the model a parameterized expression of spherical reflectance and transmitance of the atmosphere is confirmed, and the weighted single scatter albedo and weighted asymmetric factor are introduced to fit four empirical correction factors responsible for radiative fluxes in the inhomogeneous atmosphere. For both clean and turbid models, there are 120060 sets of radiative flux simulations for accuracy checks of the model, which cover 0-50 cloud optical depths, 0-0.8 surface reflectance, Junge and Log-normal aerosol size distributions, and 0-0.05 imaginary parts of aerosol refractive indexes. In case of the homogeneous atmosphere, standard errors of the 120060 upward fluxes from the present model are 1.08% and 1.04% for clean and turbid aerosol models, respectively; and those of the downward fluxes are 4.12% and 3.31%. In case of the inhomogeneous atmosphere, standard errors of the upward fluxes from the present model are 3.01% and 3.48% for clean and turbid aerosol models, respectively; and those of the downward fluxes are 4.54% and 4.89%, showing a much belter accuracy than the results calculated by using an assumption of the homogeneous atmosphere.