多极化SAR数据反演额济纳冲积扇地表参数

Surface Parameters Retrieval from Alluvial Fan in Ejina Area of Inner Mongolia Using Multi-polarization SAR Data

本文采用遗传算法和后向散射模型相结合的方法,探讨了多极化SAR(Synthetic Aperture Radar)数据反演冲积扇地表参数(地表粗糙度和土壤湿度)的可行性。通过理论模拟和实地地表测量对比,表明该方法在反演冲积扇地表参数方面是切实可行的。该方法可以根据获取数据情况不同,灵活调整反演的代价函数式,并且用于反演的SAR图像必须大于(或等于)两景,数据越多,反演结果越精确。在此基础上,利用ENVISAT ASAR数据和ALOS PALSAR数据,对内蒙古额济纳冲积扇的地表参数进行了反演计算。结果表明,额济纳冲积扇地面相对比较平坦,粗糙度参数变化较小,大部分地区均方根高度小于1.0cm。黑河沿岸地区粗糙度参数较大,而远离黑河的戈壁滩地表粗糙度较小。该地区的土壤湿度反演结果表明,该地区属于极端干旱区域,大部分地区土壤体积含水量低于10%。

The surface parameters of alluvial fan consist of roughnesss and moisture. It is very important to show the characteristics and formation of alluvial fan using these parameters. Synthetic aperture radar （SAR） is sensitive to surface texture and roughness, so it is a power tool to retrieve the surface parameters of alluvial fan. This paper presents the method of retrieving surface parameters of alluvial fan using multi-polarization SAR data based on Genetic Algorithm combined with backscattering mode. The comparison of simulated results and field measurements shows that the method is efficient for surface parameters retrieval from alluvial fan. This method presented that the cross function of surface parameters inversion could be variable with the amount of data acquired. The data used for surface parameters inversion must be more than two scenes. The more data could generate the more accurate results. Then the surface parameters of the alluvial fan in Ejina Area of Inner Mongolia were estimated using ENVISAT ASAR and ALOS PALSAR data. The estimation results show the ground surface of Ejina alluvial fan is very flat, so the range of its roughness is small, and the root mean squared heights in most party of the alluvial fan are no more than 1.0 cm. The roughness in the area along the Heihe River is big, and it is very small in the other areas far from the Heihe River. The estimation result of soil moisture shows that this area is very arid, and the soil moisture volume in most part is no more than 10%.