基于双时相ASAR影像的土壤湿度反演研究  

Inversion of soil moisture using bi-temporal ASAR images

作　　者：赵少华[1] 杨永辉[2] 邱国玉[1] 胡玉昆[2] 熊育久[1] 

机构地区：[1]地表过程与资源生态国家重点实验室(北京师范大学),北京师范大学资源学院,北京100875 [2]中国科学院遗传与发育生物学研究所农业资源研究中心,河北省节水农业重点实验室,石家庄050021

出　　处：《农业工程学报》2008年第6期184-188,共5页Transactions of the Chinese Society of Agricultural Engineering

基　　金：中国科学院知识创新工程重要方向项目(KZCX3-SW-446)

摘　　要：地表粗糙度和湿度是影响裸地后向散射系数的重要因素,为了探求ENVISAT-ASAR数据监测土壤湿度在国内的应用,该文以ASAR影像数据为基础,利用Zribi-Dechambre(2002)经验模型研究了中国科学院南皮农业生态试验站附近一裸地的表面粗糙度和地表湿度。对雷达入射角进行归一化处理使之满足模型需求,反演结果表明该区地表粗糙度主要分布0.05～0.50cm之间,土壤体积含水率大多分布在10%～34%之间,局部区域由于一些积水沟渠,使得土壤体积含水率较高,这与调查的实际情况相符合。反演的土壤湿度用地面实测值验证,结果发现模拟值和实测值具有较好的一致性,其RMSE误差为3.7%。该文介绍了在没有地表先验知识的情况下,利用扣除掉土壤粗糙度影响的后向散射反演模型获取土壤湿度的方法。该法仅需要两景相邻近时相并且不同入射角的HH同极化雷达影像,根据其后向散射系数的差值Δσo即可估算出粗糙度和土壤湿度参数,从而方便快捷地监测局部区域的土壤湿度状况。Soil surface roughness and soil moisture play critical roles in influencing backscattering coefficient, in order to investigate the application of soil moisture estimation by ENVISAT-ASAR data in China, therefore based on the ASAR image, with resolution of 30 m, the soil surface roughness characteristics and the bare soil moisture content, near Nanpi ecological experimental station of Chinese Academy of Sciences, were inversed by using an empirical model. The results show that, surface roughness mostly ranges from 0.05-0.50 cm, surface volumetric moisture mainly distributes in the range of 10%-34%, and minority show high, owing to some accumulated water ditches, which were all consistent with ground investigation. Meanwhile, the inversed results of soil moisture were validated by ground truth measured data, and a very good agreement between simulated and measured data was observed, with the residual RMSE error of 3.7%. In this study, a soil moisture inversion methodology was introduced using backscattering model which deducts the effect of surface roughness, without a-prior information on surface roughness. The methodology just needs tv^o＇HH polarized ASAR images, with a short time for inversion and different incidence angles. Roughness and moisture can be estimated by the difference of radar signal, which provides an available method for monitoring soil moisture quickly over local areas.

关 键 词：高级合成孔径雷达 土壤湿度 遥感影像 反演 后向散射系数 粗糙度 

分 类 号：TP751[自动化与计算机技术—检测技术与自动化装置]