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1.引言植被的微波遥感是下一代卫星系统的最重要目标之一,该卫星系统的目的是监测全球变化和了解全球的水循环,生物地球化学和能量。虽然,对陆地表面的微波发射已做了许多理论与实验工作,但是,从遥感数据中提取生物物理参量,还需要逃一步研究与努力,才能较好地了解微波与物质相互作用的机理。总之,植被层是空气与植物要素(叶、茎、果实)的混合物,其在微波范围内的电磁特征能用具有不同形状和大小可与波长相比较的不均匀性的随机介质来描述。有如下二种方法可使植被的微波特性模型化:即一种是“连续介质”法,在此方法中,植被用平均介电率及其波动来描述;另一种是“离散元”法,在此方法中,植被按离散的随机分布的损耗散射体
1. Introduction Microwave remote sensing of vegetation is one of the most important goals of the next generation of satellite systems whose purpose is to monitor global changes and to understand the global water cycle, biogeochemistry and energy. Although many theoretical and experimental work has been done on the microwave emission on the land surface, extracting biophysical parameters from remote sensing data still needs to be studied and diligently in order to get a better understanding of the mechanism of the interaction between microwave and matter. In summary, the vegetation layer is a mixture of air and plant elements (leaves, stems, fruits) whose electromagnetic signature in the microwave range can be described in randomized media with non-uniformities of different shapes and sizes comparable to wavelengths. There are two ways to model the microwave characteristics of vegetation: one is the “continuum” method, in which the vegetation is described by the average dielectric constant and its fluctuations; the other is the “discrete Yuan ”method, in this method, the vegetation is scattered randomly by scattered scatterers