| Water is the most important material basis of all life on the Earth, and it is an importantcarrier of earth material and energy exchange. Especially in arid and semi-regions, wheredrought, perennial precipitation, evapotranspiration and strong, barren land, water is themost sensitive and active factor. Although soil water is only a small portion of soil water(0.005%) in the world’s water resources, it can affect the Earth’s surface and the waterexchange between the atmosphere and has a direct impact on climate change, ground-airinterface between substance, energy exchange and interaction between the atmosphere,hydrosphere.Dynamic changes of soil moisture has been an important topic of research at home andabroad, while the traditional method of measuring soil moisture measurement points aremostly based on the need to establish a high-density network of observation points in thefield,that’s very cumbersome and complex to collect and process the data. With thedevelopment of remote sensing technology, the use of remote sensing technology to monitorsoil moisture Shows many advantages, the main advantage lies in its monitoring of a widerange of high efficiency, low cost, but also long-term, dynamic monitoring. Microwaveremote sensing with time throughout the day, weather observation advantages, and to have acertain ability to penetrate the surface and can compensate for optical and infrared remotesensing methods in soil moisture monitoring applications inadequate for large areas, a widerange of soil moisture monitoring provides new methods and channels to obtain a highimportance in the study of soil moisture. After the surface soil moisture and spaceborneSynthetic Aperture Radar (SAR) radar has a direct correlation to the scattering coefficient forthe inversion of soil moisture provides the possibility.Many studies show that, C-Band estimated0~5cm layer of bare soil surface moisturecan achieve better accuracy. Radarsat-2SAR provides multi-angle and multipolarity C-bandSAR data for surface soil moisture monitoring,it has great potential in extracting soil moistureinformation. The main purpose of this paper is using the C-band SAR data to estimate thesurface soil moisture in the blown-sand region, the main results are as follows:(1)Considering ground and vegetation cover bare ground microwave scattering modelapplicability analysis, combined with NDVI of study area, select the microwave scatteringproperties of the exposed surface of microwave scattering model simulation of surface area,choose a good portrait of microwave scattering characteristics of the surface AIEM modelsimulations with the polarization of the scattering data, the cross-polarization backscatter characteristics described by OH common cross-polarized backscatter data later in the sameratio and polarization AIEM simulation model.(2) Collecting and processing RADARSAT-2data and the field sampling data of thestudy area.(3) Using AIEM model to simulate the C-band microwave radar backscattercharacteristics and revealing radar backscatter coefficient changes with the variation of theparameters.(4) establisng the microwave scattering surface characteristics database of the study areaof, and analyzing the backscattering coefficient and soil moisture, the combination of therelationship between the roughness, the backscattering coefficient, soil moisture andcombined methods established by nonlinear regression between the logarithm of theexpression, the use of HV/HH polarization backscatter coefficients to inverse comprehensiveroughness, in order to establish the retrieval model of the soil moisture using radarbackscatter coefficient.(5) the use of RADAR-SAT2backscattering coefficient, soil moisture inversion modelwere applied and validated in the study area, the results show the value of soil moisturebetween the inversion inversion model obtained in this study to establish the actual measuredvalues beach area is relatively flat in the wind, low vegetation cover has a good surface, thecorrelation coefficient R2reached0.8309, the absolute error,relative error and RMSE arerespectively1.29%,14.8%and3.44. It shows that C-band SAR data of RADSAT-2can beused to invert the soil moisture in blown-sand region. |
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