Development Argolithms for Hydrological Information by Using Systhetic Aperture Radar

大区域水文信息对于了解陆面与大气的相互作用具有重要意义。现在，欧洲遥感卫星（ERS-1）和日本地球资源卫星-1（JERS-1）等卫星上安装的合成孔径雷达有望详细观测地表水文状况。本研究的重点是土壤水分，积雪和土地覆盖。（a）微波传感器测量的后向散射系数不仅受土壤湿度的影响，还受其他因素如极化、入射角、传感器频率、表面粗糙度、土壤成分等的影响。根据C波段散射仪系统的野外实验，土壤湿度的微波特征如下：i.在裸露土壤的情况下，随着入射角的增加，后向散射系数值减小。ii.随着入射角的增加，土壤水分敏感性增大，相关系数减小 ...更多信息 发现交叉偏振和入射角为20 °时是较好的系统组合。（B）微波技术为雪地测绘提供了重要的优势。一个是全天候能力，另一个是直接检测雪水当量的可能性。利用星载合成孔径雷达（SAR）和地面测量技术，在富山、长冈和札幌等地进行了积雪主动微波遥感的理论和实验研究，并将英国1975年提出的微波传输理论应用于积雪中。利用辐射传输理论和瑞利散射模型计算了积雪的后向散射系数。该理论是基于地面上的几个散射介质层。地面散射计测量结果表明，雪面和雪层界面为类镜面反射。模型模拟结果表明，在Tpyama和Nagaoka地区，由于雪介质损耗大，地面后向散射的影响不可检测，而体积散射在这些地区更为重要。(C)A利用日本名古屋附近矢田河流域的JERS-1和ERS-1 SAR数据、Landsat TM数据和SPOT P模式数据，研究了流域信息的采集方法及其精度。结果表明：（1）水域的平均后向散射系数小于其他土地覆盖;（2）在划分水域时，ERS-1 SAR数据优于JERS-1 SAR数据;（3）除水域外，其他土地覆盖之间的边界很难同时利用ERS-1和JERS-1 SAR数据进行清晰识别。少

The hydrological information at large area important to know the interaction between the land surface and the atmosphere. Now the synthetic aperture radars mounted on satellites such as the European Remote Sensing satellite(ERS-1) and the Japanese Earth Resources Satellite-1(JERS-1) are expected to observe the surface hydrological conditions in detail. This study focuses on the soil moisture, snow and land cover.(a)The backscattering coefficient measured by microwave sensors in affected not only by soil moisture but also other factors such as polarization, incident angle, sensor's frequency, surface roughness, soil composition etc. Based on the field experiments using the C-band scatterometer system, the microwave signatures of soil moisture were shown as follows :i.In case of the bare soil, as incident angle increases, the backscattering coefficient value decreases.ii.As incident angle increases, the soil moisture sensitivity increases while the correlation coefficient decreases.iii.T … More he better system combination is found to be the cross-polarization and incident angle at 20degree.(b)Microwave techniques offer important advantages for snow mapping. One is the all weather capability and hye other is the possibility to detect snow water equivalent directly. The theoretical and experimental study on the active microwave remote sensing of snow were conducted at Toyama, Nagaoka and Sapporo using the spaceborne SAR and gound surveying.The theory proposed by England in 1975 was applied to the microwave transfer in snow. The radiative transfer theory and Rayleigh scattering model were used to obtain the backscattering coefficient of snow. The theory is based upon several scattering dielectric layrs over the gound. The results of the measurement using the ground based scatterometer showed that the snow surface and the interface of snow layrs were quasi-specular. The model simulations showed that the effect of ground surface backscattering was not detectable because of the large dielectric loss of snow in Tpyama and Nagaoka and that the volume scattering was more inportant in those area.(C)A method for collecting drainage information and its accuracy was investigated using JERS-1 and ERS-1 SAR data, Landsat TM data and SPOT P-mode data obtained in Yata River Basin near Nagoya in Japan. The results were shown as follows :i.The mean backscattering coefficient is smaller in a water area than in the other land cover.ii.To delineate a water area, it is better to use the ERS-1 SAR data than the JERS-1 SAR data.iii.To identify boundaries clearly between various land covers except a water area is difficult by the use both of ERS-1 and JERS-1 SAR data. Less