ASTER thermal infrared observations over New Mexico

Abstract

The Advanced Spaceborne Thermal Emission Reflectance Radiometer (ASTER) has acquired more than a dozen clear sky scenes over the Jornada Experimental Range in New Mexico since the launch of NASA's Terra satellite in December, 1999. To support the ASTER overpasses there were simultaneous field campaigns for the 5/09/00, 5/12/01, 9/17/01 and 5/15/02 scenes. Also, data from an airborne simulator, MASTER, were obtained for the 5/12/01 and 5/15/02 scenes to provide high resolution (3 m) data roughly coincident with ASTER. The Jornada Experimental Range is a long term ecological reserve (LTER) site located at the northern end of the Chihuahuan desert. The site is typical of a desert grassland where the main vegetation components are grass and shrubs. The White Sands National Monument is also within several of the scenes. ASTER has 5 channels in the 8 to 12 micrometer wave band with 90 meter resolution and thus is able to provide information on both the surface temperature and emissivity. The Temperature Emissivity Separation (TES) algorithm was used to extract emissivity values from the ASTER data for 5 sites on the Jornada and for the gypsum sand at White Sands. The results are in good agreement with values calculated from the lab spectra for gypsum and with each other. The results for sites in the Jornada show reasonable agreement with the lab results when the mixed pixel problem is taken into account. These results indicate ASTER and TES are working very well. The surface brightness temperatures from ASTER were in reasonable agreement with measurements made on the ground during the field campaigns.