草地土壤水分遥感反演方法的适用性

Applicability of remote sensing inversion models for estimating regional soil moisture in Chinese grasslands

应用MODIS数据,构建中国草地的3种土壤水分反演模型[表观热惯量(apparent thermal inertia,ATI)、温度植被干旱指数(temperature vegetation drought index,TVDI)和植被供水指数(vegetation supply water index,VSWI)],利用实测土壤水分和AMSR2数据进行验证,对3种模型适用性进行了研究。结果表明:3种模型反演结果与实测土壤水分呈现不同程度相关性,从区域整体上均能反映土壤水分时空变化;ATI模型适用于冬季草丛生态系统、草甸生态系统、高寒稀疏植被和冻原生态系统的土壤水分反演,但不适用于草原生态系统,并且夏季误差较高;TVDI模型春季在草丛生态系统、草甸生态系统、高寒稀疏植被和冻原生态系统适用性好,但是冬季反演结果偏差大;VSWI模型夏季误差较小,并且适用于反演草原生态系统土壤水分。

Using MODIS data,three soil moisture inversion models(ATI,TVDI,and VSWI)of Chinese grasslands were constructed,and the output of the three models was verified using measured soil moisture data and AMSR2 data to assess the models’applicability.The inversion results of the three models were correlated with measured soil moisture to varying degrees,which may reflect spatial and temporal variation of soil moisture in the entire region.The ATI model was considered suitable for estimating soil moisture inversion in grass ecosystems,meadow ecosystems,and in alpine sparse vegetation and tundra ecosystems in winter;however,it produced high error rates regarding summer soil moisture inversion.Furthermore,this model was considered unsuitable for soil moisture inversion of grassland ecosystems.The TVDI model showed good applicability regarding grass ecosystems,meadow ecosystems,and in alpine sparse vegetation and tundra ecosystems in spring,but it produced considerable deviation in winter.The VSWI model showed low error rates in summer,and it was considered suitable for soil moisture inversion of grassland ecosystems.