Fig 1.
Land borders have been created using data from https://www.naturalearthdata.com/.
Fig 2.
Interannual variations of surface soil moisture across different (a) landforms, (b) ecosystems, and (c) soil types.
Fig 3.
Individual effects on surface soil moisture variability (p = 0.000).
(a) precipitation, (b) evaporation, (c) temperature, (d) NDVI.
Table 1.
Explanatory power (R2) of driving factors. Individual versus combined effects on soil moisture variability across landforms (Flatlands, Mountains), ecosystems (Farmland, Forest, Grassland), and soil types (Luvisols, Cambisols, Regosols, Gleysols, and Solonchaks).
Fig 4.
Interannual variation trends of annual (a) average surface soil moisture, (b) precipitation, (c) evaporation and (d) average surface temperature.
Table 2.
Results of the Mann-Kendall trend test.
Table 3.
Results of the Mann-Kendall abrupt change detection.
Fig 5.
The UF-UB curves of annual (a) average surface soil moisture, (b) precipitation, (c) evaporation and (d) average surface temperature.
Fig 6.
Trend of seasonal variation of surface soil moisture content.
Spring (March, April, May); Summer (June, July, August); Autumn (September, October, November); Winter (December, January, February).
Table 4.
Results of the M-K trend test for SM in different seasons.
Fig 7.
The scatter plot between the annual average surface soil moisture and three climatic factors.
Table 5.
Pearson correlation coefficients between SM and three climatic factors.
Fig 8.
Spatial distribution of multi-year average (a) surface soil moisture, (b) precipitation, (c) evaporation, and (d) surface temperature.
Fig 9.
Spatial distribution of the Pearson correlation coefficient between surface soil moisture and (a) precipitation, (b) surface temperature.
Fig 10.
Spatial distribution of the Pearson correlation coefficient between surface soil moisture and evaporation.
(a) dry season, (b) wet season.
Fig 11.
Wavelet analysis of surface soil moisture content sequence.
(a) The real part isolines map of wavelet coefficients; (b) Wavelet coefficient variance map.
Fig 12.
Wavelet analysis of annual precipitation sequence.
(a) The real part isolines map of wavelet coefficients; (b) Wavelet coefficient variance map.
Fig 13.
Wavelet analysis of annual evaporation sequence.
(a) The real part isolines map of wavelet coefficients; (b) Wavelet coefficient variance map.
Fig 14.
Wavelet analysis of annual average surface temperature sequence.
(a) The real part isolines map of wavelet coefficients; (b) Wavelet coefficient variance map.
Fig 15.
Cross-correlation coefficients between soil moisture and annual precipitation, evaporation, and average surface temperature.
Fig 16.
Lag response of soil moisture at different depths to precipitation at the monthly scale.
Fig 17.
Monthly lag response of soil moisture to precipitation across soil depths and types.