Fig. 2

(a) Spatial distribution of the SM stations, including 434 representative and 1623 failed stations. (b) Valid data length and the number of target SM stations per soil layer from 2000 to 2023.

(a) Spatial distribution of the SM stations, including 434 representative and 1623 failed stations. (b) Valid data length and the number of target SM stations per soil layer from 2000 to 2023.