Temporospatial Variation Of Soil Moisture Across The Tibetan Plateau Based On Multi-source Remote Sensing

Soil moisture is an important parameter in the process of water resources and water cycle,and its temporospatial distribution and variation reflect the spatial difference and variation of regional water balance.The Tibetan Plateau is regarded as a sensitive region of global climate change and an ecologically fragile region.Over the past half century,the precipitation on the Tibetan Plateau has increased,and the soil moisture content of the plateau has changed accordingly.Understanding the changes in the soil moisture on the Tibetan Plateau is of great significance to the hydrological process research and disaster warning on the Tibetan Plateau.Due to the special geographical environment of the plateau and the scarcity of field observation data,soil moisture products based on remote sensing have provided the possibility for large-scale and continuous studies on spatiotemporal variation of soil moisture.However,due to systematic errors in the observation process,differences in algorithms and spatial and temporal scales between products,existing soil and aquatic products currently have certain limitations,and the obtained soil and water data also have great uncertainties.In this study,the Tibetan Plateau was used as the study area,and the extended triple allocation method(ETC)of three kinds of soil is used to analyze the uncertainty of aquatic products.By selecting the soil water data with higher accuracy and analyzing the spatial and temporal changes of soil moisture in the study area,the following points of knowledge were obtained:(1)the consistency of the three products on the Tibetan Plateau shows that the consistency of soil moisture products in the west and east of the Tibetan Plateau is lower(R~2is lower)than that of the south and north(R~2is higher).Compared with GLEAM and ESA CCI soil moisture products,ERA-Interim soil moisture products have less uncertainty and higher accuracy.(2)from the perspective of changes in the year,decreased from April to May,and increased from June to July.From the perspective of seasonal variation,the soil moisture content is higher in summer and generally lower in winter.According to the spatial distribution,the soil moisture content in the northern region of the Tibetan Plateau was relatively low,while that in the southern and eastern regions was relatively high and the soil was relatively moist.(3)according to the data of interannual changes,there is a significant fluctuation in the soil moisture content of the Tibetan Plateau.From 1980 to 2003,the continuous increase of soil moisture was the main factor.From 2003 to 2009,soil moisture declined.After 2009,it showed an upward trend.(4)correlation analysis between different climate factors and soil water shows that precipitation is the main reason affecting soil water content.There was a positive correlation between precipitation and soil moisture content,that is,increased precipitation can make the soil moist.Temperature is also the factor that affects the spatial and temporal changes of soil moisture,which is positively correlated with soil moisture content.The correlation between wind speed and soil moisture content was very weak,which shows a negatively correlation with soil moisture content.