Submitted to: Global Energy and Water Cycle Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: August 29, 2001
Publication Date: N/A
Technical Abstract: Knowledge of the surface emissivity is important for determining the radiation balance at the land surface. For arid lands with sparse vegetation the problem is difficult because the emissivity of the exposed soils and rocks is highly variable. Multispectral thermal infrared data from the Advanced Spaceborne Thermal Emission Reflectance Radiometer (ASTER) instrument provides a new tool for estimating emissivity. ASTER ha 5 channels in the 8 to 12 micrometer band with 90 meter resolution. These data can be used to assess the spectral variations of surface emissivity. We will present ASTER data acquired over the Jornada Experimental Range and White Sand National monument in New Mexico in May 2000 & 2001. The Jornada site is typical of a desert grassland where the main vegetation components are grass and shrubs. Good quantitative agreement with laboratory measurements was found for the emissivities extracted for the gypsum sands of the White Sands. For the sites within the Jornada the results were qualitatively consistent with ground measurements made with a multi-channel CIMEL radiometer having similar bands to those of ASTER. The resulting estimates of the surface emissivity are in good agreement with the laboratory measurements of the soils emissivity spectra. The results show considerable variation amongst the samples in the 8 to 9.5 micrometer region. Thus it is now possible to estimate the spectral emissivity variation for these surfaces on a global basis at high spatial resolution.