自然地表红外辐射特性统计分析

A THEORETICAL MODEL FOR IR RADIANCE STATISTICS OF NATURAL TERRAIN

利用Ｍｏｎｔｅ－Ｃａｒｌｏ（Ｍ－Ｃ）方法，模拟计算了自然地表红外辐射的统计特性．根据地表能量热平衡方程，选取短波吸收率、长波发射率、风速以及热传导率（对光裸地表而言）和气孔阻力（对植被型地表而言）为独立的随机变量，并假设它们均服从正态分布；给出了自然地表温度的概率分布，讨论了这些随机变量的空间起伏和环境条件对植被红外辐射统计特性的影响．研究表明，在这些随机变量中，短波吸收率和风速对自然地表红外辐射统计特性的影响最大．

A theoretical model for IR radiance statistics of natural terrain was presented by using Monte Carlo simulation. The model is based on the heat balance equation of the natural terrain and the assumption that the short wavelength absorptance, long wavelength emissivity, wind speed and heat conductivity (for bare soil) or bulk stomatal resistance (for vegetation canopy) are random, uncorrelated variables with normal distribution densities.The results show that due to nonlinear coupling of the temperature to the thermal properties and heat source, the radiance distribution varies in a complex manner while the heat source changes. In the random variables selected, the influence of the field fluctuation in the short wavelength absorptance and wind speed on the statistical nature of the vegetation canopy is most obvious.