Temporal and spatial variations in soil moisture in Northern China as demonstrated by CCI data

Due to sparse, uneven data distribution, poor data continuity, poor large scale-research, soil moisture data of European Space Agency Climate Change Initiative (ESA CCI) was applied to five agro-ecological zones in Northern China. Pearson correlation coefficient was used to validate remote sensing data, spatio-temporal persistence was used to analyze spatial-temporal variations in soil moisture. ESA CCI remote-sensing soil-moisture data set was found to have good spatial and temporal adaptability to Northeast China in summer, in Northwest China in spring, in Loess Plateau in spring and summer, and in Inner Mongolia Plateau in summer and autumn. The annual average soil moisture in Northern China from 1991-2016 was found to be 0.06-0.39 m³∙m⁻³. Gradual increase in soil water content was found from west to east, with the highest values in summer. Lower seasonal values were found in autumn, winter and spring. Important grain production areas in the Northeast, Loess Plateau and Huang-Huai-Hai region demonstrated great fluctuations with time and season, a tendency to dry out was also revealed.