Study on the law of radiant directionality of row crops

The style of crops planting is frequently in row-structure, the row-structure style may result in big difference among the sunlit, shaded soil surface and foliage temperatures and cause pixel component to vary in azimuth orientation, these further lead to the change of radiant directionality of row crops in the zenith and azimuth orientations. Since the row crops are often tackled as isotropic in the azimuth orientation based on continuous vegetation assumption, big errors will be brought about. In order to eliminate the errors, it is necessary to study the law of radiant directionality of the row crops. In this paper, Monte Carlo method has been employed to simulate the angular effects on radiation caused by row architecture parameters. The simulated results show that the parameters, for example, row height, row width, row interval between the neighbor rows and the leaf area index have significant influences on the radiant directionality, but the azimuth orientation ranks the first among the parameters.

连续植被的热辐射方向性

正确认识非同温混合像元热辐射方向性规律是利用多角度遥感数据反演像元组分温度的前提。论文基于局地热平衡条件和组分有效发射率概念探讨了连续植被的热辐射方向性模型。模型表明同温下的热辐射方向性只决定于连续植被体系总有效发射率的方向性 ,它是各组分有效发射率的和 ,决定于植被叶面和土壤表面的发射率、冠层结构参数。在非同温状况下 ,组分温度通过组分有效发射率调节体系的辐射亮度方向变化。模型解释了热辐射中孔穴效应问题。并通过蒙特卡罗逆向模拟从微观探讨了热辐射方向性与植被叶面和土壤表面的发射率、冠层结构参数的关系 ,并对孔穴效应引起体系发射率的增量和辐射亮度的增量进行了模拟分析。结果表明 ,对于球面型连续植被 ,叶面和土壤表面发射率值分别取 0 .98和 0 .94时 ,垂直方向上孔穴效应使体系的总有效发射率有 0 .0 1— 0 .0 2 5幅度的增值。当连续植被处于 2 0℃同温状况时 ,孔穴效应引起的辐射亮度增量基本上都在 0 .8℃以上 ,最高可达到 1.3℃。