Comparison of SMAP, GLDAS and simulated soil moisture datasets over a Malaysian region

Abstract

Availability of soil moisture observations at a high spatial-temporal resolution is a prerequisite for various agricultural applications. This paper presents the comparison of SMAP (Analysis & Geophysical) and GLDAS soil moisture products versus a customized high resolution land surface model over a region representative of tropical regions located in Malaysia. The in-situ data over a nine month period is used to evaluate SMAP, GLDAS and customized LSM soil moisture. An overestimation of SMAP and GLDAS soil moisture products to in-situ data was noticed whereas customized LSM performed better with RMSE at surface 0.05 m3/m3 (ubRMSE: 0.048 m3/m3) and rootzone 0.04 m3/m3 (ubRMSE: 0.037 m3/m3) in this study. Both the SMAP products found similar and GLDAS is marginally better than SMAP. The result of this study is useful to support the continuous improvement of the SMAP soil moisture retrieval model, especially in tropical regions. The evaluation across the study region indicates that the customized LSM is able to capture spatial-temporal variation of soil moisture with better accuracy.