Slope gradient and slope aspects for 30 arc sec grids have been compiled using elevation data from the Shuttle Radar Topography
Mission (SRTM). The SRTM data is publicly available as 3 arc second (approximately 90 meters resolution at the equator) DEMs
- High resolution SRTM data have been used also for calculating an elevation map describing median elevation in each grid
- Distributions of nine slope gradient classes are available for each grid-cell: 0–0.5%, 0.5–2%, 2–5%, 5–8%, 8–16%, 16–30%,
30–45%, and > 45%.
- Slope aspect data are stored in distributions of five classes namely: Class 1: slopes below 2% undefined aspect; Class
2: slopes facing North (315°–45°); Class 3: East (45°–135°); Class 4: South (135°–225°), and Class 5: West (225°–315°).
The NASA Shuttle Radar Topographic Mission (SRTM) has provided digital elevation data (DEMs) for over 80% of the globe.
The SRTM data is publicly available as 3 arc second (approximately 90 meters resolution at the equator) DEMs (CGIAR-CSI,
2006). For latitudes over 60 degrees north elevation data from GTOPO30 (USGS, 2002) with a resolution of 30 arc-seconds
(depending on latitude this is approximately a 1 by 1 km cell size) were used
CGIAR-CSI (2006): NASA Shuttle Radar Topographic Mission (SRTM). The SRTM data is available as 3 arc second (approx. 90m
resolution) DEMs. The dataset is available for download at: http://srtm.csi.cgiar.org/
USGS (2002): GTOPO30 – Global 30 arc second elevation data. U.S. Geological Survey, National Mapping Division, EROS Data
Center; for download available at: http://edcdaac.usgs.gov/gtopo30/gtopo30.html.
The datasets are available in ASCI files from the IIASA website http://www.iiasa.ac.at/Research/LUC/luc07/External-World-soil-database/HTML/global-terrain-slope-download.html?sb=7