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Proceedings Paper

Applicability of thermal infrared surface emissivity ratio for snow/ice monitoring
Author(s): Hideyuki Tonooka; Akira Watanabe
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Paper Abstract

In snow/ice remote sensing with the thermal infrared (TIR) spectral region, the most important target parameter is surface temperature which is a key parameter in climate process studies. Surface emissivity is usually an uncertain factor in temperature determination, but laboratory measurements indicate that snow/ice emissivity spectra include some information on conditions such as grain size and cementation. We therefore investigate the applicability of a spectral emissivity change to snow/ice condition monitoring. First, snow/ice emissivity spectra extracted from a spectral library are evaluated, and the surface emissivity ratio (SER) of two bands located between 10.5 and 12.5 micro is proposed as a snow/ice condition index. Next, snow/ice emissivity spectra measured on site with a multi-band TIR radiometer are shown to have a spectral behavior almost consistent with the library spectra. Then, two-band temperature/emissivity separation (TES) equations for snow/ice surfaces for AVHRR, ASTER, and MODIS, which can be used for retrieving surface emissivities at two bands, are derived from the spectral library. Finally, the SER images acquired by ASTER and MODIS over snow/ice fields around Abashiri, Japan, and Dry Valley, Antarctica, are evaluated. The results show that the SER has a spatial variation of 1 or 2% over snow/ice surfaces, and also the thermal log residual (TLR) ratio as well as the SER is useful for snow/ice condition monitoring. Consequently, the SER and the TLR ratio will be useful for detecting some difference of snow/ice conditions under clear sky conditions in either daytime or nighttime.

Paper Details

Date Published: 20 January 2005
PDF: 9 pages
Proc. SPIE 5655, Multispectral and Hyperspectral Remote Sensing Instruments and Applications II, (20 January 2005); doi: 10.1117/12.579929
Show Author Affiliations
Hideyuki Tonooka, Ibaraki Univ. (Japan)
Akira Watanabe, Ibaraki Univ. (Japan)

Published in SPIE Proceedings Vol. 5655:
Multispectral and Hyperspectral Remote Sensing Instruments and Applications II
Allen M. Larar; Makoto Suzuki; Qingxi Tong, Editor(s)

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