87th AMS Annual Meeting

Wednesday, 17 January 2007
A global infrared land surface emissivity database and its validation
212B (Henry B. Gonzalez Convention Center)
Eva Borbas, Univ. of Wisconsin, Madison, WI; and L. Moy, S. W. Seemann, R. Knuteson, P. Antonelli, J. Li, H. L. Huang, I. Trigo, and L. Zhou
Poster PDF (664.0 kB)
Two global infrared land surface emissivity databases with high spectral and high spatial resolution will be introduced. The databases are derived from a combination of high spectral resolution laboratory measurements of selected materials, and MODIS (MOD11) observed land surface emissivities at 3.7, 3.9, 4.0, 8.5, 11.0 and 12.0 micron wavelengths. For a given month, a spectrum of emissivity from 3.7 to 14.3 micron is available for every latitude/longitude point globally at 0.05-degree resolution.

For the first database, a baseline emissivity spectra (BES) is derived from laboratory measurements of high spectral emissivity. The BES are derived at moderate spectral resolution (10 values in the 3.7-14.3 micron range), with wavelengths chosen as the inflection points that best characterize the shape of each relevant laboratory emissivity spectra. Then BES are applied by adjusting the magnitude of the emissivity at each of the inflection point wavelengths based on the observed MODIS MOD11 emissivity values. The result of the BES adjustment is a spectrum of emissivity at the inflection points for each month at each MOD11 latitude and longitude point (0.05 degree resolution) over land.

For the second database, principal component analysis of 332 laboratory spectra and MODIS emissivity observations were used to create a high spectra resolution emissivity dataset. Then the first 6 principal components are used to reconstruct the spectra for each MOD11 grid points over land.

Both methods will be implemented and run for three years of global data. For validation, the datasets will be compared with other emissivity measurements from selected field experiments, and with the land surface emissivity derived for use in land surface temperature retrieval from SEVIRI data on METEOSAT-8.

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