CLM4.5 Model Simulation of Soil Moisture over the Qinghai-Xizang Plateau and Its Performance Evaluation

The Community Land Model version 4.5 (CLM4.5) driven by atmospheric forcing data (CRUNCEP) is used to simulate spatial and temporal characteristics of soil moisture in the Qinghai-Xizang Plateau for the period 1981-2016. Compared with station data, two reanalysis products (i.e.,the ERA-Interim and GLDAS-CLM) and the microwave remote sensing FY-3B/MWRI data, it is found that CLM4.5 can well reproduce the spatial and temporal variations of soil moisture in the Qinghai-Xizang Plateau. The microwave data with high spatial resolution (0.1°×0.1°), which is derived from various satellite remote sensing in the Qinghai-Xizang Plateau, provides detailed description of the spatial features of soil moisture. The results show that the spatial and temporal distributions of simulated soil moisture are consistent with station observations.The simulation is significantly correlated with observations in all soil layers but with high systematic deviations. And the consistency between simulation and observations gradually decreases from the surface downward. The spatial distribution of soil moisture in the Qinghai-Xizang Plateau is characterized by gradual increase from northwest to southeast. The high-value areas are found in the Sanjiangyuan Wetland and the southeastern Plateau, while the dry regions are located in the Qaidam Basin and the Tarim Basin. Soil moisture generally increases from surface downward. Temporal variation of soil moisture presents an alternate dry and wet pattern. There is little difference in soil moisture variation in different layers. The simulation also reasonably reproducesmonthly changes in soil moisture in the summer. Soil moisture in most of the southwestern region including the southern periphery of the plateau obviously increases in the summer. The dry area in the northern Qaidam Basin also markedly shrinks to the north. The simulated soil moisture provides more detailed description of spatial distribution and monthly changes of soil moisture in the summer compared with reanalysis data and microwave remote sensing data.