Extraction of phisical parameters for energy and water flux estimation for a wide area by using satellite remote sensing data set

本研究的目的是开发一种利用卫星遥感数据集提取大范围能量和水通量物理参数的新方法，为此主要进行了以下四个主题的研究。研究了欧洲ERS-1遥感卫星和日本JERS-1地球资源卫星两颗新卫星合成孔径雷达（SAR）图像的特征。合成孔径雷达（SAR）观测到的后向散射系数受到表面几何粗糙度障碍物的影响。利用该属性，利用日本地球资源卫星（JERS-1）和欧洲遥感卫星（ERS-1）获得的SAR图像估算了空气动力粗糙度参数的空间分布。将这些粗糙度图与Kondo和Yamazawa（1986）提出的使用国家土地数值信息的方法得到的粗糙度图进行比较。结果表明，JERS-1 SAR反演的粗糙度图与国家土地数值信息反演的粗糙度图具有较好的一致性。空间表面粗糙度信息对于估算表面通量的空间分布是非常重要的。本研究利用理论表面散射模型，从JERS-1和ERS-1观测到的后向散射系数和表层土壤含水量中提取表面粗糙度参数，并分析后向散射系数和土壤含水量对提取的表面粗糙度参数的敏感性。在Biwako项目区，提取的表面粗糙度参数与观测值相吻合。在旱田，提取值与观测值吻合较好。研究了遥感数据集像元大小对热通量空间均值估算的影响。

The aim of this research is to develop a new methodology to extract phisical parameters for energy and water flux estimation for a wide area by using satellite remote sensing data set For the purpose, mainly following four topoics have been conducted.1.The characteristics of synthetic aperture rader (SAR) images obtained by two new satellite : the European Remote Sensing Satellite (ERS-1) and the Japanese Earth Resources Satellite (JERS-1) were investigated.2.The backscattering coefficients observed by synthetic aperture radar (SAR) are influenced by surface geometric roughness obstacles. By using this attributes, spatial distributions of aerodynamic roughness parameter are estimated from the SAR images obtained by the Japanese Earth Resources Satellite (JERS-1) and European Remote Sensing Satellite (ERS-1). These roughness maps are compared with the roughness map derived by the method proposed by Kondo and Yamazawa (1986) which uses the National Land Numerical Information. As a result, it is shown that the roughness map derived from JERS-1 SAR corresponds well to the roughness map derived from the National Land Numerical Information.3.Spatial surface roughness information is very important to estimate a spatial distribution of surface fluxes. In this study, by using theoretical surface-scattering models, surface roughness parameters are extracted from the backscattering coefficients observed by JERS-1 and ERS-1 and surface soil moisture volumetric content, and sensitivity analysis of backscattering coefficients and soil moisture content to the extracted surface roughness parameters are performed. In the Biwako Project area, the extracted surface roughness parameter sare compared with observed ones. The extracted values and observed ones correspond well at the dry paddy fields.4.The influence of pixel size of remote sensing data set for estimation of spatial mean of heat flux was investigated.