Limitations of using a thermal imager for snow pit temperatures
Driven by temperature gradients, kinetic snow metamorphism plays an import role in avalanche formation. When gradients based on temperatures measured 10 cm apart appear to be insufficient for kinetic metamorphism, faceting close to a crust can be observed. Recent studies that visualised small-scale...
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ftdoajarticles:oai:doaj.org/article:c076d6016a704f3e8134827a8135d477 2023-05-15T18:32:30+02:00 Limitations of using a thermal imager for snow pit temperatures M. Schirmer B. Jamieson 2014-03-01T00:00:00Z https://doi.org/10.5194/tc-8-387-2014 https://doaj.org/article/c076d6016a704f3e8134827a8135d477 EN eng Copernicus Publications http://www.the-cryosphere.net/8/387/2014/tc-8-387-2014.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 1994-0416 1994-0424 doi:10.5194/tc-8-387-2014 https://doaj.org/article/c076d6016a704f3e8134827a8135d477 The Cryosphere, Vol 8, Iss 2, Pp 387-394 (2014) Environmental sciences GE1-350 Geology QE1-996.5 article 2014 ftdoajarticles https://doi.org/10.5194/tc-8-387-2014 2022-12-31T15:58:02Z Driven by temperature gradients, kinetic snow metamorphism plays an import role in avalanche formation. When gradients based on temperatures measured 10 cm apart appear to be insufficient for kinetic metamorphism, faceting close to a crust can be observed. Recent studies that visualised small-scale (< 10 cm) thermal structures in a profile of snow layers with an infrared (IR) camera produced interesting results. The studies found melt-freeze crusts to be warmer or cooler than the surrounding snow depending on the large-scale gradient direction. However, an important assumption within these studies was that a thermal photo of a freshly exposed snow pit was similar enough to the internal temperature of the snow. In this study, we tested this assumption by recording thermal videos during the exposure of the snow pit wall. In the first minute, the results showed increasing gradients with time, both at melt-freeze crusts and artificial surface structures such as shovel scours. Cutting through a crust with a cutting blade or shovel produced small concavities (holes) even when the objective was to cut a planar surface. Our findings suggest there is a surface structure dependency of the thermal image, which was only observed at times during a strong cooling/warming of the exposed pit wall. We were able to reproduce the hot-crust/cold-crust phenomenon and relate it entirely to surface structure in a temperature-controlled cold laboratory. Concave areas cooled or warmed more slowly compared with convex areas (bumps) when applying temperature differences between snow and air. This can be explained by increased radiative and/or turbulent energy transfer at convex areas. Thermal videos suggest that such processes influence the snow temperature within seconds. Our findings show the limitations of using a thermal camera for measuring pit-wall temperatures, particularly during windy conditions, clear skies and large temperature differences between air and snow. At crusts or other heterogeneities, we were unable to create a ... Article in Journal/Newspaper The Cryosphere Directory of Open Access Journals: DOAJ Articles The Cryosphere 8 2 387 394 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
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ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
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Environmental sciences GE1-350 Geology QE1-996.5 M. Schirmer B. Jamieson Limitations of using a thermal imager for snow pit temperatures |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
Driven by temperature gradients, kinetic snow metamorphism plays an import role in avalanche formation. When gradients based on temperatures measured 10 cm apart appear to be insufficient for kinetic metamorphism, faceting close to a crust can be observed. Recent studies that visualised small-scale (< 10 cm) thermal structures in a profile of snow layers with an infrared (IR) camera produced interesting results. The studies found melt-freeze crusts to be warmer or cooler than the surrounding snow depending on the large-scale gradient direction. However, an important assumption within these studies was that a thermal photo of a freshly exposed snow pit was similar enough to the internal temperature of the snow. In this study, we tested this assumption by recording thermal videos during the exposure of the snow pit wall. In the first minute, the results showed increasing gradients with time, both at melt-freeze crusts and artificial surface structures such as shovel scours. Cutting through a crust with a cutting blade or shovel produced small concavities (holes) even when the objective was to cut a planar surface. Our findings suggest there is a surface structure dependency of the thermal image, which was only observed at times during a strong cooling/warming of the exposed pit wall. We were able to reproduce the hot-crust/cold-crust phenomenon and relate it entirely to surface structure in a temperature-controlled cold laboratory. Concave areas cooled or warmed more slowly compared with convex areas (bumps) when applying temperature differences between snow and air. This can be explained by increased radiative and/or turbulent energy transfer at convex areas. Thermal videos suggest that such processes influence the snow temperature within seconds. Our findings show the limitations of using a thermal camera for measuring pit-wall temperatures, particularly during windy conditions, clear skies and large temperature differences between air and snow. At crusts or other heterogeneities, we were unable to create a ... |
format |
Article in Journal/Newspaper |
author |
M. Schirmer B. Jamieson |
author_facet |
M. Schirmer B. Jamieson |
author_sort |
M. Schirmer |
title |
Limitations of using a thermal imager for snow pit temperatures |
title_short |
Limitations of using a thermal imager for snow pit temperatures |
title_full |
Limitations of using a thermal imager for snow pit temperatures |
title_fullStr |
Limitations of using a thermal imager for snow pit temperatures |
title_full_unstemmed |
Limitations of using a thermal imager for snow pit temperatures |
title_sort |
limitations of using a thermal imager for snow pit temperatures |
publisher |
Copernicus Publications |
publishDate |
2014 |
url |
https://doi.org/10.5194/tc-8-387-2014 https://doaj.org/article/c076d6016a704f3e8134827a8135d477 |
genre |
The Cryosphere |
genre_facet |
The Cryosphere |
op_source |
The Cryosphere, Vol 8, Iss 2, Pp 387-394 (2014) |
op_relation |
http://www.the-cryosphere.net/8/387/2014/tc-8-387-2014.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 1994-0416 1994-0424 doi:10.5194/tc-8-387-2014 https://doaj.org/article/c076d6016a704f3e8134827a8135d477 |
op_doi |
https://doi.org/10.5194/tc-8-387-2014 |
container_title |
The Cryosphere |
container_volume |
8 |
container_issue |
2 |
container_start_page |
387 |
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394 |
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