Abstract:
Soil moisture has been a critical research object in climate,hydrology,ecology and agriculture. However,soil moisture monitoring can not meet the needs of large-scale area applications if only relying on site data. Recent studies have shown that high-quality satellite soil moisture data is a good substitute for site data. This paper selects the observed soil moisture data of 30 agrometeorological stations to evaluate accuracy of the GLEAM satellite soil moisture in the Huaihe River Basin. Results show that:(1) Compared with the measured results of agrometeorological stations,on a single-point scale,the accuracy of the satellite soil moisture data in different stations is significantly different.In terms of watershed scale assessment,the GLEAM data has a relatively high accuracy. The correlation coefficient of soil moisture in both surface and root zone layer is more than 0.7,among which the surface layer is close to the mean value of the measured data and the soil moisture in root zone layer is somewhat underestimated.(2) In terms of spatial distribution,both GLEAM and agrometeorological stations data show that the soil moisture in the Huaihe River Basin is high in the south and low in the north,high in the east and low in the west,while soil moisture in the southern Huaihe River and the coastal areas of Yi and Shu River is relatively large. Based on the advantages of wide range and continuous space of satellite soil moisture monitoring,it is suggested that it should be used in large-scale regional soil moisture research.(3)The average soil moisture in the Huaihe River Basin has a significant inter-annual change. Since 1980,soil surface layer and root zone layer have shown a downward trend,especially in spring. The inter-annual variation of soil moisture in summer and autumn is large due to the influence of inter-annual variation of drought and flood in the basin. Overall,the GLEAM satellite data has relatively high precision and good stability in the basin scale assessment,which can make up for the lack of site monitoring data,and has an important application prospect in the basin agricultural production,flood forecasting,drought assessment and water resources assessment.