Modeling angular-dependent spectral emissivity of snow and ice in the thermal infrared atmospheric window

Masahiro Hori, Teruo Aoki, Tomonori Tanikawa, Akihiro Hachikubo, Konosuke Sugiura, Katsuyuki Kuchiki, Masashi Niwano

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)


A model of angular-dependent emissivity spectra of snow and ice in the 8-14 μm atmospheric window is constructed. Past field research revealed that snow emissivity varies depending on snow grain size and the exitance angle. Thermography images acquired in this study further revealed that not only welded snow particles such as sun crust, but also disaggregated particles such as granular snow and dendrite crystals exhibit high reflectivity on their crystal facets, even when the bulk snow surface exhibits blackbody- like behavior as a whole. The observed thermal emissive behaviors of snow particles suggest that emissivity of the bulk snow surface can be expressed by a weighted sum of two emissivity components: those of the specular and blackbody surfaces. Based on this assumption, a semi-empirical emissivity model was constructed; it is expressed by a linear combination of specular and blackbody surfaces' emissivities with a weighting parameter characterizing the specularity of the bulk surface. Emissivity spectra calculated using the model succeeded in reproducing the past in situ measured directional spectra of various snow types by employing a specific weighting parameter for each snow type.

Original languageEnglish
Pages (from-to)7243-7255
Number of pages13
JournalApplied Optics
Issue number30
Publication statusPublished - Oct 20 2013
Externally publishedYes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Engineering (miscellaneous)
  • Electrical and Electronic Engineering


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