2.2.3. Land Cover Type and DEM

A subset of the global land cover product from Tsinghua University at 10 m resolution in 2017 (available at http://data.ess.tsinghua.edu.cn (accessed on 15 July 2021)) was used to define our study area for its high spatial resolution and high overall accuracy [45], as shown in Figure 1. The SRTM digital elevation model (DEM) data at 90 m resolution were used to characterize the variations in snow phenology and vegetation phenology. The DEM data were freely downloaded from the Geospatial Data Cloud (http://www.gscloud.cn (accessed on 15 July 2021)) and processed to UTM/WGS-84 projection and 500 m resolution, as shown in Figure 1c.
