利用主被动微波数据联合反演土壤水分

Joint Inversion of Soil Moisture Using Active and Passive Microwave Data

在黑河中游干旱区水文试验的基础上,以临泽站为研究区域,探讨主被动微波数据联合反演土壤水分的方法。针对ALOS/PALSAR数据,使用AIEM理论模型计算地表的同极化后向散射系数,Oh半经验模型描述交叉极化散射特征,通过对大量后向散射模拟数据的分析,建立裸露地表粗糙度计算模型;利用模拟数据分析地表辐射亮温随土壤水分和粗糙度的变化规律,在此基础上构建NN模型结合粗糙度计算结果和辐射计飞行数据反演研究区域的土壤水分。地面同步测量数据的验证结果表明,该方法充分发挥了主被动微波数据各自的优势,同时避免了主被动协同过程中的尺度问题,为流域尺度的土壤水分监测提供了一种新的有效途径。

In this paper, on the basis of the Heihe hydrological drought experiments, the active and passive microwave data joint inversion method of soil moisture has been explored as Linze Station for the study area. For ALOS/PALSAR data, co-polarization backscattering coefficient was calculated using the theoretical model AIEM, and Oh semi-empirical model was used to describe the characteristics of cross-polarization scattering. By a large number of back-scattering simulation data analysis, a calculation model of surface roughness was established. With the use of simulation data, changes of surface radiation brightness temperature with soil moisture and roughness were analyzed. Based on this, a neural network model was built to combine roughness calculation results and the flight data, and soil moisture of the study area was estimated with the trained model. Verified results with synchronous measurement data showed that the method can give full play to the active and passive microwave data on their respective strengths, while avoiding the main problem of scaling issues with passive and active data. And it provides a new effective way for basin-scale monitoring of soil moisture.