Soil moisture plays a crucial role in the hydrological cycle and climate system. The reliable estimation of soil moisture in space and time is important to monitor and even predict hydrological and meteorological disasters. Here we studied the spatiotemporal variations of soil moisture and explored the effects of precipitation and temperature on soil moisture in different land cover types within the Tarim River Basin from 2001 to 2015, based on high-spatial-resolution soil moisture data downscaled from the European Space Agency’s (ESA) Climate Change Initiative (CCI) soil moisture data. The results show that the spatial average soil moisture increased slightly from 2001 to 2015, and the soil moisture variation in summer contributed most to regional soil moisture change. For the land cover, the highest soil moisture occurred in the forest and the lowest value was found in bare land, and soil moisture showed significant increasing trends in grassland and bare land during 2001~2015. Both partial correlation analysis and multiple linear regression analysis demonstrate that in the study area precipitation had positive effects on soil moisture, while temperature had negative effects, and precipitation made greater contributions to soil moisture variations than temperature. The results of this study can be used for decision making for water management and allocation.

Soil moisture plays a critical role in land-atmosphere interactions. Quantifying the controls on soil moisture is highly valuable for effective management of water resources and climatic adaptation. In this study, we quantified the effects of precipitation, temperature, and vegetation on monthly soil moisture variability in an arid area, China. A non-linear Granger causality framework was applied to examine the causal effects based on multi-decadal reanalysis data records. Results indicate that precipitation had effects on soil moisture in about 91% of the study area and explained up to 40% of soil moisture variability during 1982–2015. Temperature and vegetation explained up to 8.2% and 3.3% of soil moisture variability, respectively. Climatic extremes were responsible for up to 10% of soil moisture variability, and the importance of climatic extremes was low compared to that of the general climate dynamics. The time-lagged analysis shows that the effects of precipitation and temperature on soil moisture were immediate and dissipated shortly. In addition, the effects of precipitation on soil moisture decreased with the increase of precipitation, soil moisture, and elevation. This study provides deep insight for uncovering the drivers of soil moisture variability in arid regions.