祁连山区不同植被类型上的SMOS遥感土壤水分产品质量评估

Validation of SMOS Soil Moisture Products on Different Vegetation Types in Qilian Mountain

为了分析SMOS遥感土壤水分产品在祁连山区的真实性和可靠性,利用祁连山区内布设于7种主要植被类型上的34个实测站点的实测土壤水分数据对其进行质量评估。首先挑选与实测值相对应的SMOS数据,进而依次计算每个站点上遥感产品与实测值的相关系数R、Bias和均方根误差RMSE,从而得到SMOS数据在不同植被类型上不同尺度(年和季节)的反演精度。结果表明:SMOS遥感土壤水分产品在研究区内是可信的,但低估了研究区土壤水分值,且未能达到产品预期目标0.04m^3/m^3。SMOS产品对于植被辐射反演效果好于土壤辐射反演,导致其在植被覆盖度越高的区域与实测值的拟合程度越高。SMOS产品在湿润条件下性能优于干旱条件,在变异性小的地区性能优于变异性大的地区。在季节尺度上,SMOS遥感产品与实测值拟合程度在夏、秋两季远好于春季。

Observation data of 34 in-situstations located in seven main vegetation types were used to evaluate the performance of SMOS soil moisture products in Qilian Mountain,Northwest China.SMOS data were processed to correspond to the observation data,and three indices：R、Bias and RMSE were calculated at both annual and seasonal scales for each observation station.Results show that SMOS products were credible in the study area,but underestimated soil moisture in Qilian Mountain,and failed to achieve the intended accuracy target of 0.04 m^3/m^3.SMOS performed better in estimating vegetation emission than soil emission,leading to its better performance in areas with higher vegetation coverage.Similarly,SMOS performed better in the humid condition than the arid condition,and also better in areas with smaller soil moisture variability than those with large soil moisture variability.At seasonal scale,SMOS products fitted the observations better in the summer and autumn than the spring.