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| Titel |
Use of a thermal imager for snow pit temperatures |
| VerfasserIn |
C. Shea, B. Jamieson, K. W. Birkeland |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 6, no. 2 ; Nr. 6, no. 2 (2012-03-15), S.287-299 |
| Datensatznummer |
250003478
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| Publikation (Nr.) |
 copernicus.org/tc-6-287-2012.pdf |
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| Zusammenfassung |
| 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 of 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 with snow, 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. Further study is needed to use absolute temperatures independently of supporting gradient data. |
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