[Temporal and spatial variations of soil moisture in North China]

Soil moisture is an important hydrological parameter and a basic element for research in water cycle and climate change. Using hourly recorded soil moisture data of 374 stations from the new generation of automatic soil moisture encryption observation network constructed by China Meteo-rological Administration, we analyzed the spatial and temporal variations of soil moisture in North China from 2013 to 2019 and the relationship with precipitation and temperature. The results showed that soil moisture in 10-100 cm layer decreased fluctuatly as a whole, with the decreasing at the 100 cm being serious. The spatial distribution of soil moisture at different depths was characterized by high in the southeast and low in the northwest. About 63% of the surface layer was short of moisture. Soil moisture at different depths changed significantly with the seasons. In summer, soil moisture of each layer reached the highest and soil entropy of each layer was suitable, while it reached a low point in spring. Soil moisture was closely correlated with precipitation and temperature, but the correlation got weaker gradually with the increase of soil depth. Soil moisture was more sensitive to precipitation than to temperature.