ASTER Observations of the Spectral Emissivity for Arid Lands

On May 9, 2000 the Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) on the Terra satellite obtained data over the Jornada Experimental Range test site along the Rio Grande river and the White Sand National Monument in New Mexico. ASTER has 14 channels from the visible (VNIR) through the thermal infrared (TIR) with 15 m resolution in the VNIR and 90 m in the TIR. The overpass time is approximately 11 AM. With 5 channels between 8 and 12 m these multispectral TIR data from ASTER provide the opportunity to separate the temperature and emissivity effects observed in the thermal emission from the land surface. Ground measurements during these overflights included surface temperature, vegetation type and condition and limited surface emissivity measurements. There was also an aircraft flight with the MODIS/ASTER simulator on June 14, 2000, unfortunately not coincident with a satellite overpass. Preliminary results indicate good agreement between ASTER brightness temperatures and ground measures. Analysis of earlier aircraft data has shown that the multispectral TIR data are very effective for estimating both the surface temperature and emissivity. These results will be compared with those obtained from the ASTER data for this site. With multispectral thermal infrared observations provided by ASTER it is possible for the first time to estimate the spectral emissivity variation for these surfaces on a global basis at high spatial resolution.