Extremely heavy rains fell at the end of February 2012 in the northern Algerian province of El Tarf, near the Tunisian border. The rainfall total was the greatest recorded in the last 30 years. The Seybouse River overflowed its banks, submerging adjacent villages. Overflow from the Bougous, Mexa and Cheffia dams added to the misery. In this image from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft, acquired March 1, 2012, vegetation is shown in red and water is depicted as black to turquoise, depending on how much sediment it contains. The image is located at 36.7 degrees north latitude and 8.3 degrees east longitude. It covers an area of 22 by 37.2 miles (34 by 60 kilometers).
With its 14 spectral bands from the visible to the thermal infrared wavelength region and its high spatial resolution of 15 to 90 meters (about 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 Terra. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and data products.
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. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.
The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate, Washington, D.C.
More information about ASTER is available at http://asterweb.jpl.nasa.gov/.