Validation/calibration Of The SMOS Microwave Remote Sensing Soil Moisture

Soil moisture monitoring and accurately acquiring is great significance for explore the mechanism of global water cycle, construct climate and hydrological model, monitor crop growth, forecast drought disasters and so on. Microwave remote sensing has become one of the most effective means to monitor soil moisture rely on the advantages of all-weather, day and night observation, ability to penetrate surface etc.This paper mainly concentrated on the north of Henan plain region which in front of Taihang Mountains, and carried out the validation/calibration of the SMOS L2 soil moisture data products. The results and innovations are mainly in the following aspects:(1)The average-average and node-site validation methods were carried out to SMOS L2 soil moisture products. The results shows that in the 3 pixels and the 9 sites, the correlation coefficient of the SMOS and the Insitu are mainly concentrated in 0.20 ~ 0.40, also the existence of dry bias mainly concentrated in the 0.06 ~ 0.14, the changes and improvements of soil dielectric model from Dobson to Mironov make the difference between the SMOS and Insitu decreases, and SMOS soil moisture has a seasonal performance, especially in summer.(2)Analyze the influence factors on the quality of SMOS soil moisture produncts: ① Precipitation, the correlation coefficient of the Precipitation between SMOS and Insitu are 0.25, 0.23 respectively. Continuous precipitation affect SMOS observation, when precipitation reaches in torrential rain, it has a persistent effect on soil moisture. ②Land cover, the proportional of pixel land cover have an effect on the difference between the SMOS and Insitu; the typical regional heterogeneity influence on soil moisture retention. ③ RFI, RFI have a slightly increasing trend; the different geographical position, the influence of RFI is also different.(3)Especially for RFI influence factors, the contaminated SMOS L2 soil moisture data were filtered with the filter abnormal value criteria and filter RFI formula, then the validation shows that in the pixel 1 and 4 sites the correlation coefficient of the filtered SMOS and the Insitu are mainly concentrated in 0.10 ~ 0.32,the filtered data in alleviating numerical wave, but fail to improve on the verification accuracy.