基于SPOT-VGT可见光/短波红外波段数据对AMSR-E土壤湿度的降尺度研究  

Down-scaling AMSR-E Derived Soil Moisture Using SPOT-VGT Visible/Shortwave Infrared Data

作　　者：李梦云[1] 黄方[1] 

机构地区：[1]东北师范大学地理科学学院,吉林长春130024

出　　处：《遥感技术与应用》2016年第2期342-348,共7页Remote Sensing Technology and Application

基　　金：国家自然科学科学基金项目(41571405);国家自然科学基金面上项目(41271196)资助

摘　　要：基于SPOT-VGT数据,由短波红外、红和蓝波段反射率计算了表征地表土壤湿度的可见光—短波红外干旱指数(VSDI),通过对1km空间分辨率的VSDI影像进行空间升尺度处理,采用多种函数建立了25km空间分辨率AMSR-E土壤湿度数据与VSDI指数的关系,发现二者关系最符合S型曲线模型,拟合残差在空间上呈现随机分布的特征。基于S曲线函数关系下的1km预测土壤湿度和残差值,对AMSR-E土壤湿度进行降尺度模拟,得到1km空间分辨率的土壤湿度。将原始AMSR-E土壤湿度和实测数据对降尺度结果分别比较验证后,表明基于该方法获得的土壤湿度模拟精度较高。High-resolution optical/ infrared data can be utilized to improve the low spatial resolution of mi- crowave soil moisture data using downscaling methods.The Visible and Shortwave Infrared Drought Index （VSDI） derived from the information of shortwave infrared （SWIR）,red and blue channels is regarded as an effective surface wetness indicator.A downscaling approach for AMSR-E soil moisture based on VSDI is proposed in this study.Firstly,the VSDI was calculated based on SPOT-VGT images with the spatial scale of 1 kin.Secondly,the VSDI images were aggregated into AMSR-E soil moisture data scale （25 km）.Third- ly,the correlations between aggregated VSDI and AMSR-E soil moisture at 25 km spatial scale were ex plored.It was found that S-curve fitting function could provide insight into the relationship and the fitted residuals exhibited characteristics of randomly distributed in space.Finally,the predicted soil moisture and the fitted residuals at lkm spatial scale based on S-curve model were used to downscale AMSR-E soil mois ture product.The downscaled soil moisture was validated by in situ observations and AMSR-E soil mois- ture.The results suggest that the proposed downscaling method with good precision can be used to improve the spatial resolution of microwave soil moisture data.

关 键 词：土壤湿度 AMSR-E SPOT-VGT 可见光—短波红外干旱指数(VSDI) 降尺度 

分 类 号：S152.7[农业科学—土壤学] TP79[农业科学—农业基础科学]