This Global Digital Elevation Model, or GDEM, is a product of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), a joint program of NASA and Japan's Ministry of Economy, Trade and Industry. The image was released on June 29, 2009, and was created by processing and stereo-correlating the 1.3 million-scene ASTER archive of optical images, covering Earth's land surface between 83 degrees North and 83 degrees South latitudes. The GDEM is produced with 98-feet postings, and is formatted as 23,000 one-by-one-degree tiles. In this colorized version, low elevations are purple, medium elevations are greens and yellows, and high elevations are orange, red and white.
With its 14 spectral bands from the visible to the thermal infrared wavelength region and its high spatial resolution of 50 to 300 feet, ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched Dec. 18, 1999, on NASA's Terra satellite.
The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping and monitoring of dynamic conditions and temporal change.