Development and Application of a sub-daily in-situ Snow Depth Dataset over China (1951―2023)

A high-quality, long-series, real-time updatable snow depth dataset collected from in-situ observations by National Meteorological Information Centre is developed, which is crucial for evaluating snow depth model and satellite remote sensing products. A comprehensive quality control procedure was applied to snow depth in-situ observations, including the check of metadata, limit values, temporal consistency, temperature-snow depth consistency, precipitation-weather phenomenon-temperature-snow depth consistency, and spatial consistency to identify erroneous data. About 0.8% erroneous data were identified, especially the false “0” value and the erroneous extremes at 148 stations, that ensured the quality of the dataset. The dataset comprises of snow depth observations from about 2400 sites spanning from 1951 to 2023, with data completeness ranging from 80-90% at each station. Based on this dataset, the study investigates the spatial distribution of different seasons, the three major snowpack zones, extreme values, and climate trends of mean daily snow depth and the number of snow-cover days. The findings highlight the highest snow depth and the number of snow-cover days in specific regions, such as northeast China, eastern Inner Mongolia, northern Xinjiang, and the Tibetan Plateau (15-20cm and over 80 days in winter), with spatial variability observed on the Tibetan Plateau. Significant increasing trends are observed in Northeast China, eastern Inner Mongolia, and northern Xinjiang, while decreasing trends are observed in the North China plain and Tibetan Plateau.