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根据离散方法建模垄行结构农田表面微波发射率,与地基多频率微波辐射计实测发射率比较发现:二者之间的平均绝对偏差小于0.01,证实了利用离散化方法建模农田表面微波发射率的可行性。在给定条件下不同观测方位角农田表面微波发射率与平坦表面的发射率差值在0.02与0.05之间,这说明农田结构微波辐射具有各向异性,行结构对发射率的影响在农田电磁波辐射建模过程中不可忽略。本文分析了不同土壤湿度条件下农田垄行结构可能引起的土壤湿度反演误差,结果表明,土壤湿度变化范围是0.02—0.5cm3/cm3,垄行结构引起的土壤湿度反演误差为0—0.1cm3/cm3,此误差超过了土壤湿度反演的容限值,因此在进行农田参数的遥感提取过程中不可忽略周期性垄行结构对表面发射率的影响。
According to the discrete method, the microwave emissivity of farmland surface with ridge-line structure was compared with the measured emissivity of multi-frequency microwave radiometer. The average absolute deviation between the two was less than 0.01, which confirmed that using the discretization method to model the surface microwave emission Rate of feasibility. Under certain conditions, the difference of emissivity between microwave emissivity and flat surface of farmland at different azimuth angles of observation is between 0.02 and 0.05, which shows that microwave radiation in farmland structure has anisotropy. The influence of row structure on emissivity is in electromagnetic fields Radiation modeling process can not be ignored. In this paper, the soil moisture retrieval error caused by farmland ridge structure under different soil moisture conditions is analyzed. The results show that the range of soil moisture change is 0.02-0.5cm3 / cm3, the error of soil moisture retrieval caused by ridge structure is 0-0.1 cm3 / cm3, the error exceeds the tolerance of soil moisture inversion. Therefore, the influence of periodic ridge structure on the surface emissivity can not be neglected in the remote sensing extraction of farmland parameters.