Variability in observed snow depth over China from 1960 to 2014

Snow depth is a critical variable that reflects snow variability and has an important impact on the energy and hydrological cycles. However, snow depth changes in response to regional climate warming have not been quantified in detail across China. Here, we investigated the variability in observed snow depth based on a recently released dataset collected at 1,500 stations from 1960 to 2014. To address the non-normal distribution of daily snow depth data, the annual cumulative amount of snow depth (CASD) is employed, and the trend is calculated and tested for the change point and field significance. The results showed that CASD experienced a slight increase of 1.75%center dot decade(-1) in China. An increasing trend of CASD was observed in Northeastern and Northwestern China, a decreasing trend was observed in the eastern Tibetan Plateau, Loess Plateau, and Yangtze River Basin, and these changes were more remarkable after the 2000s. Since the 2000s, the increased CASD in Northwestern and Northeastern China has been accompanied by a significant decrease in winter temperature and a sharply increasing trend in snowfall events in the northeastern region. The decreased CASD in the Eastern Tibetan Plateau and Loess Plateau after the 2000s was accompanied by a decrease in snowfall events and an increase in winter temperature. Large-scale atmospheric circulation, such as the Arctic Oscillation (AO), has a remarkable regional effect on the variability in snow depth. Statistically significant negative correlations were found in the northern part of China (i.e., positive AO phase with reduced CASD), while significant positive correlations were shown in the middle part of China (i.e., positive AO phase with enhanced CASD). Furthermore, China experienced an obviously shorter snow season during the whole period (decreased by 3.87%center dot decade(-1)), jointly resulting from later starting dates and earlier ending dates.