Microwave Scattering Measurements And Soil Moisture Estimation Studies

Water is not only requirements for the livings, but also the necessary carrier for the matter and energy exchanging. Although soil moisture constitutes only about 0.005% of the global water resources, it's important as a boundary condition forhydrologic and climate models. Soil moisture directly effects the energy and hydrology exchange between earth surface and atmosphere cycle, and has further influences on the climates changing.Soil moisture content plays a critical role in the surface energy balance at the soil-atmosphere interface and can be considered as a key state variable that influences the distribution of the radiant energy, the runoff generation and the percolation of water into the soil. Soil moisture monitor is always a focus in hydrology, meteorology and agriculture researches.Microwave remote sensing can work at anytime and under any weather conditions, and it also has high sensitivity to soil moisture, which makes it have been wildly used in the soil moisture study. Contrast with other microwave sensors, although microwave radiometer is more sensitive to soil moisture, but because of its low resolution and relative band-design limitation, it is difficult to offer good soil moisture result for user. Backscatter coefficient observed by active microwave remote sensors, has high relation with surface dielectric constant, which makes it a possible data resource to retrieve soil moisture. After years of research, soil moisture retrieval with active microwave remote sensor data has been advanced a lot, but it still works well at the bare surface.The microwave scatterometer is a non-imaging, active and looking awry to observational remote sensor. It mainly used to measure the back-scattering energy, identify the category of the measured object and predict its characters and changes. Birrer etc. used scatterometer data first and manifested its land-application ability after studying the radar backscattering coefficient of the rain forest of Amazon with Sea-A Satellite Scatterometer (SASS) data. Subsequently, Kennett etc. utilized the ocean satellite scatterometer data to study the scatterometer data of the land-cover of the earth's surface, further confirmed the potential of scatterometer data in land-application. In recent years, making use of the ERS-1 scatterometer data to study global land obtained good application results.Recently years, a lot of novel microwave sensors have been developed, and they offered more new observation modes, which made multi-angle observations data available. But, contrast with relative high application ability of optics remote sensing data, multi-band, multi-polarization, multi-angle information contained in microwave remote sensing data has not been used effectively, which is just the reason of this dissertation. In the dissertation, we will discuss how to use multi-band, multi- polarization, multi-angle information in soil moisture retrieval based on the measured datas of FM-CW X, C, S, L-band scatterometer, and focus the work on C and S two bands'data and develop soil moisture retrieval expirence modles for these two bands. It will be ready for the validation of the mechanism of remote sensing the HJ-1C saltlite and help to combine the best work parameter in using microwave sensing for multi-bands, multi-polarization SAR.