云间屏蔽对块状云阵短波辐射参数的影响

EFFECT OF CLOUD SHADOW ON SHORTWAVERADIATION PARAMETERS OF REGULARCLOUD ARRAY

本文使用短波辐射传输方程建立分析模式研究规则排列块状云阵的短波辐射参数。模式中考虑了云对地表的遮光、邻近云对地表反射光的遮挡以及云侧面之间、云侧与地表之间的散射与吸收。本模式最大特色是加入了云体间相互屏蔽。这点由于其复杂性而多为以前的研究者所忽略。与不考虑此效应的Ｂｒａｄｌｅｙ［１］模式所得结果比较，本模式在太阳天顶角较大时对云阵辐射参数有较大修正，说明计算云体短波辐射参数必须考虑云体间屏蔽效应。文章中还研究了块状云阵短波辐射参数与μ０（太阳高度角的余弦）、Ｒｓ（地表反照率）等因子之间的关系，并与相同厚度平面平行云体短波辐射参数进行了比较。

An analytic model is developed by using solar radiation transfer equation to study shortwave radiation parameters of regular cloud array. The model includes many factors such as the limited view of the ground due to nearest clouds , the shade onthe earth casted by clouds , the scattering and absorbing between cloud sides , cloud and earth surface, etc. The main feature of this model is the reduction of direct solar input due to shadowing by a neighboring cloud and this , due to its complexity,is neglected by precious researchers. Compared with the results of Bradley's model which doesn't consider the shadow effect., the shortwave radiation parameters of this model have great improvement at large solar zenith angle. This shows that the effect of shadow must be considered to simulate shortwave radiation parameters. In addition , the shortwave radiation parameters of regular cloud array are compared with those of plane-parallel cloud at same optical depth. The relations between radiation parameters of regular cloud array and other factors such as μ0(cosine of solar zenith angle) . R3(albedo of earth sur- face) are also discussed.