Evaluation And Merging Study Of Multiple Passive And Active Microwave Remotely Sensed Soil Moisture Products In China

Soil moisture is an important environmental factors and process parameters of meteorology and climatology.The objective accuracy of our understanding of climate change and the interaction between land and air is affected by the measurement accuracy of soil moisture.The analysis of remote sense soil moisture data has important significance.At present,with the ability to penetrate cloud and capture the regional and global scale surface soil moisture information,active and passive remote sensing are widely used in soil moisture monitoring.In situ soil moisture data which was seriously quality controlled and precipitation data are used to determine the reliability of three active and passive remote sensed soil moisture product(ASCAT,SMOS,FY3B)over China in year of 2012.The AVHRR Green Vegetation Fraction data was used as a reference data set for merging multiple active and passive microwave satellite soil moisture products over China in year of 2012,by triple-collocation and least-square method.The merged soil moisture product(BLEND)was compared with the NOAA Soil Moisture Operational Product(SMOPS).The main conclusions are as follows:It could be known from comparison that among these three satellite soil moisture products,the ASCAT data coverage was the best quality performance over China in 2012,the SMOS data rowed second.The correlation coefficient between each microwave remote sensed soil moisture product and in situ soil moisture data which was seriously quality controlled showed that:ASCAT soil moisture products quality best,in the performance of the stability of the Chinese each region;SMOS is seriously affected by radio frequency interference,during some periods of time appear abnormal fluctuations;compared to precipitation data,three satellite soil moisture products had good response with precipitation process,and each individual product lack many measured areas in China every day.Using triple-collocation and least-square method to blend multiple active and passive microwave remote sensed soil moisture products could obtain improved soil moisture products.The correlation coefficient between BLEND product and in situ soil moisture data is higher than that between single satellite soil moisture product in most areas.Compared BLEND product with SMOPS products showed that two products were similar on the spatial distribution over China;two merged products showed similar time series trend in Dongbei,Huabei,Xinan and Xibei area.The standard deviation of two merged products showed that in Huabei,Huazhong,Huanan area,BLEND product volatility is significantly greater than SMOPS product.