The Cryosphere Discuss., 5, 2523-2556, 2011
www.the-cryosphere-discuss.net/5/2523/2011/
doi:10.5194/tcd-5-2523-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal The Cryosphere (TC). Please refer to the corresponding final paper in TC.
Use of a thermal imager for snow pit temperatures
C. Shea1, B. Jamieson1,2, and K. W. Birkeland3
1Department of Geoscience, University of Calgary, Calgary, Canada
2Department of Civil Engineering, University of Calgary, Calgary, Canada
3USDA Forest Service National Avalanche Center, Bozeman, Montana, USA

Abstract. Weak snow of interest to avalanche forecasting often forms and changes as thin layers. Thermometers, the current field technology for measuring the temperature gradients across such layers – and for thus estimating the expected vapour flux and future type of crystal metamorphism – are difficult to use at distances shorter than 1 cm. In contrast, a thermal imager can provide thousands of simultaneous temperature measurements across small distances with better accuracy. However, a thermal imager only senses the exposed surface, complicating its methods for access and accuracy with respect to buried temperatures. This paper presents methods for exposing buried layers on pit walls and using a thermal imager to measure temperatures on these walls, correct for lens effects, adjust temperature gradients adjust time exposed, and calculate temperature gradients over millimetre distances. We find lens error on temperature gradients to be on the order of 0.03 °C between image centre and corners. We find temperature gradient change over time to usually decrease – as expected with atmospheric equalization as a strong effect. Case studies including thermal images and visual macro photographs of crystals, collected during the 2010–2011 winter, demonstrate large temperature differences over millimetre-scale distances that are consistent with observed kinetic metamorphism.

Citation: Shea, C., Jamieson, B., and Birkeland, K. W.: Use of a thermal imager for snow pit temperatures, The Cryosphere Discuss., 5, 2523-2556, doi:10.5194/tcd-5-2523-2011, 2011.
 
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