3.1.5. Vegetation Data

To analyze the variations in snow phenology for different vegetation types in Northeast China, the MODIS vegetation product MOD13A1 normalized difference vegetation index (NDVI) from 2001 to 2018 was derived through the GEE cloud platform with spatial resolution and temporal resolution of 500 m and 16 d, respectively. In addition, the monthly/yearly NDVI maximum of all grids was then calculated by the maximum synthesis method to eliminate the interference of clouds and shadows.

#### 3.1.6. Land Cover Data

MCD12Q1 is an annual land cover product with five classification standards. In this paper, the International Geosphere-Biosphere Program (IGBP) classification standard was chosen, and land cover types in this region were reclassified into water bodies, forested areas (including broadleaf forest, coniferous forest, mixed forest and shrub), and nonforested areas (except water and forested areas), and then we explore the differences in snow cover phenology for various underlying surfaces at the same latitude.
