The ASTER instrument that was launched onboard NASA’s Terra spacecraft in December 1999 has an along-track stereoscopic capability using two telescopes in its near infrared spectral band to acquire data from nadir and backward views. Over 1.2 million scenes (level-1A products) acquired between March 2000 and August 2008 were used to generate the ASTER Global DEM (ASTGTM) collection. A newly developed cloud mask function was applied to remove cloud effects from scene DEMs as much as possible. ASTER Global DEM was created by stacking all cloud masked DEMs, and a statistical selection algorithm was used to remove abnormal data. Several existing reference DEMs were used to correct residual anomalies where limited scenes were available, including SRTM, NED, CDED, and Alaska DEM. The ASTGTM products include DEM data and a ‘.num’ file containing quality and reference DEM information. Data Set Characteristics: Geographic Extent: Global between 83º latitude Scene Coverage: 1º x 1º tiles File Format: GEOTIFF Map Projection: Geographic Lat/Lon Datum: WGS84/EGM96 Resolution: 1 arcsecond (30-m horizontal posting at equator)

ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) is an imaging sensor onboard the Terra satellite, which was launched in December 1999 as part of NASA's Earth Observing System (EOS). ASTER is a cooperative effort between NASA, Japan's Ministry of Economy, Trade and Industry (METI) and Japan's Earth Remote Sensing Data Analysis Center (ERSDAC). ASTER data is used to create detailed maps of land surface temperature, reflectance and elevation. Data Resolution is 30 meters.