卫星土壤水分产品在青藏高原地区的适用性评价

为了分析土壤水分产品在青藏高原地区的可靠性和适用性，利用青藏高原地区地下5 cm深度的地面实测土壤水分数据，结合多种评价指标（相关系数R、均方根误差RMSE、偏差Bias和无偏均方根误差ubRMSE）对土壤水分主动-被动探测卫星（SMAP）、高级微波扫描辐射计2（AMSR2）、风云三号（FY-3B）土壤水分产品，从时间和空间两个方面进行了适用性研究。结果表明：（1）土壤水分产品均能反映青藏高原的土壤水分变化，在降水较多的季节，三种产品精度均有不同程度的下降。（2）土壤水分产品在夏季和秋季反演效果好于冬季和春季，并且在秋季与实测值更接近。其中，SMAP产品在各个区域都能反映土壤水分的季节变化趋势，并普遍在夏季高估、冬季低估；AMSR2产品在夏季低估，冬季明显高估；FY-3B产品在夏季普遍低估。（3）土壤水分产品在那曲和狮泉河地区反演结果较好，在那曲地区与实测值相关性最高；在玛曲地区表现出较大的不确定性，虽然相关系数较高，但RMSE和Bias同样较高，整体精度较差；SMAP产品在阿里地区满足目标精度。综合来看，SMAP产品在青藏高原地区反演结果较为稳定，受气候和环境的影响较小，具有相对较大的R和较小的RMSE和Bias。

Applicability evaluation of satellite soil moisture products in Qinghai-Tibet Plateau

In order to analyze the reliability and applicability of soil moisture products in the Qinghai-Tibet Plateau,the soil moisture data measured at a depth of 5 cm below the ground in the Qinghai-tibet Plateau were used. Combined with a variety of evaluation indicators including Correlation Coefficient R, root mean square error (RMSE), Bias and unbias root mean square error (ubRMSE), this paper conducted researches on the applicability of soil moisture active-passive detection satellite (SMAP), advanced microwave scanning radiometer 2 (AMSR2) and Fengyun-3B from two aspects of time and space. The results indicated that (1) all kinds of soil moisture products could reflect the changes of soil moisture in the Qinghai-Tibet Plateau. In the season with more precipitation, the accuracy of the three kinds of soil moisture products decreased to different degrees. (2) The inversion effect of soil moisture products in summer and autumn was better than that in winter and spring, and it was closer to the measured value in autumn. Among them, the SMAP could reflect the seasonal variation trend of soil moisture in all regions, while generally overestimated it in summer and underestimated in winter; the AMSR2 underestimated soil moisture in summer and significantly overestimated soil moisture in winter; FY-3B generally underestimated soil moisture in summer. (3) The results of soil moisture products inversion were good in Naqu and Shiquanhe areas. The correlation between the soil moisture products and measured data was the highest in Naqu; while in Maqu, the correlation coefficient was higher, but RMSE and Bias were also higher, the overall accuracy was poor. The SMAP met the target accuracy in the Ngari region. To sum up, the inversion results of SMAP products were relatively stable in the Qinghai-Tibet Plateau, and were less affected by climate and environment, with the relatively large R and small RMSE and Bias.