Global Relief Clasess (GRC) Dataset

Understanding the land surface morphology and its relief components, which record the dynamics of the planet's evolution and interaction of multiple environmental factors, constitutes a critical aspect of Earth system science. However, classified relief and landform data with a resolution of approximately 1 arc-second (approximately 30 m) are lacking at the global scale, which limits the progress of related studies at finer scales. We utilized several Digital Elevation Models (DEMs) and innovative approaches to classify terrain relief on the Earth's surface into two levels with 1 arc-second. Table 1 provides the meanings and colormaps for the two levels of relief. In this study, we refer to the two primary surface types as flat terrain and rugged terrain in Level 1 (L1), based on their differences in slope characteristics. These two contrasting relief classes provide essential support for understanding landform processes, analyzing hydrological patterns, and assessing the spatial distribution of human activities across diverse environmental contexts. At Level 2 (L2), the flat terrain retains elevation-based characteristics and is further divided into low-altitude, middle-altitude, high-altitude, and very high-altitude flat terrain. Rugged terrain is subdivided at L2 into low-relief, gentle-relief, moderate-relief, high-relief and very high-relief rugged terrain. We provide accessible rasterized files, with the coordinate system in WGS84 (EPSG: 3857). The cell values in each raster file represent tertiary landform types. Specifically, the first digit represents a L1 type, and the first two digits represent a L2 type. Nanjing Normal University produced this dataset with the support of the Deep-time Digital Earth (DDE) International Big Science Program.