空间斜程能见度的影响因素分析

Slant visibility: multi-factor analysis

空间斜程能见度是空间目标识别的重要参量。水平能见度与大气消光参数有明确的关系,而斜程能见度与大气消光参数、观测方向、太阳天顶角等多种因素有关,目前尚未有明确的结果。从辐射传输理论出发,通过δ Eddington近似求解辐射传输方程,尝试推导了空间斜程能见度的表达式,探讨了斜程能见度与观察者视角、太阳高度角以及大气光学特性之间的关系。

The slant visibility is an important parameter in space survey application, meteorology, remote sensing, and so on. It is wellknown the horizontal visibility has a definite relation with the atmospheric extinction coefficient, which is considered as the fundamental of meterorology,but for the slant visibility, the case is entirely different. Besides related to the atmospheric extinction coefficient, the slant visibility is evaluated to be influenced by many factors, such as the visual direction, the solar zenith angle, etc. Due to the complicated process of solving the radiative transfer equation, so far, few literatures could be obtained that described the clear numerical relations between the slant visibility and those effective factors. In this paper, based on the radiative transfer theory, an attempt to achieve the expression of the slant visibility was made by using deltaEddington approximation of the radiative transfer equation, and it was found that many reasons led to the variety of the slant visibility, including the single scattering albedo, the asymmetry factor of the phase funciton. At the succedent discussion, the relations between the slant visibility and those factors were analyzed.