Bulletin of Glaciological Research
Online ISSN : 1884-8044
Print ISSN : 1345-3807
Dependence of thermal infrared emissive behaviors of snow cover on the surface snow type(雪面の熱赤外射出特性の雪質依存性)
HORI Masahiro(堀雅裕)AOKI Teruo(青木輝夫)TANIKAWA Tomonori(谷川朋範)KUCHIKI Katsuyuki(朽木勝幸)NIWANO Masashi(庭野匡思)YAMAGUCHI Satoru(山口悟)MATOBA Sumito(的場澄人)
ジャーナル フリー

2014 年 32 巻 p. 33-45


The potential of the thermal infrared (TIR) remote sensing for discriminating surface snow types was examined by analyzing TIR radiances acquired from space over the Greenland ice sheet. The brightness temperature difference (BTD) between TIR wavelengths of 11 and 12μm was found to increase in accordance with in situ observed evolutions of surface snow type. Spatial and temporal distributions of BTD over the entire ice sheet indicated that BTD has a sensitivity of about 1.2 K for variations of the possible snow types. The observed behaviors of BTD were coincident with those predicted by a radiative transfer calculation using previous in situ measured snow emissivities, although some biases on the order of 0.1-0.3 K remain. The dependence of BTD on the surface snow type was also consistent with the behaviors of snow reflectance at the shortwave infrared (SWIR) wavelength 1.6μm, which is a measure of snow grain size, except for the case of melting wet snow. The inconsistency in the wet snow case was considered to be due to the different optical responses of the TIR and SWIR signals to wet snow, which suggested the possibility of using TIR signals to discriminate wet/dry conditions of snow cover in an old stage. As a result, it is determined that TIR remote sensing has potential not only as an approach supplementary to the SWIR method for assessing surface snow types in daytime but also as the only method for simultaneous retrieval of snow type and surface temperature in nighttime.

© 2014 公益社団法人 日本雪氷学会
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