TEMPORAL AND SPATIAL VARIATION OF SOIL MOISTURE IN CHINA BASED ON SMAP DATA

Abstract. Soil moisture is one of the most important indexes that affect crop growth and meteorological change. Widespread monitoring soil moisture is the forerunner of formulating better soil and water management measure and disaster mitigation strategies. Soil moisture (0–10cm) of SMAP L3 from April 2015 to April 2018 was cited in this paper. The accuracy of SMAP L3 was compared and evaluated by real-time products of CLDAS-V2.0 from CMA Land Data Assimilation system. The results show that SMAP L3 can reflect the objective regular of soil moisture. In addition, the spatial and temporal variation characteristics of soil moisture (0–10cm) at SMAP L3 are also analyzed, which show that the soil moisture is higher in the south than in the north and it is higher in the east than in the west of China. Moreover, the seasonal characteristics are as follows: The soil moisture is the highest in summer, and the second in autumn, while it is lower in winter and spring. Finally, based on the study of temperature and precipitation data from meteorological stations in China, it is found that there is a positive correlation between soil moisture and precipitation in south China, with a correlation coefficient of 0.5027. There is a negative correlation between soil moisture and precipitation in Northeast and northwest China and in Qinghai-Tibet region. What’s more, soil moisture has a positive correlation with temperature, with an average correlation coefficient of 0.6813; the highest correlation coefficient is 0.7752 in Northeast China.