Air Convection in the Active Layer of Rock Glaciers
Coarse blocks are an abundant surface cover in mountainous permafrost landscapes. In this coarse blocky layer, air convection occurs and has a significant influence on the ground thermal regime of the underlying permafrost. Besides heat transfer through conduction, free convection of air takes place...
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ftdoajarticles:oai:doaj.org/article:8aa05bc71226456dba321420e41dcf1b 2023-05-15T17:56:26+02:00 Air Convection in the Active Layer of Rock Glaciers Jonas Wicky Christian Hauck 2020-08-01T00:00:00Z https://doi.org/10.3389/feart.2020.00335 https://doaj.org/article/8aa05bc71226456dba321420e41dcf1b EN eng Frontiers Media S.A. https://www.frontiersin.org/article/10.3389/feart.2020.00335/full https://doaj.org/toc/2296-6463 2296-6463 doi:10.3389/feart.2020.00335 https://doaj.org/article/8aa05bc71226456dba321420e41dcf1b Frontiers in Earth Science, Vol 8 (2020) rock glacier convection active layer two-dimensional modeling heat transfer permafrost Science Q article 2020 ftdoajarticles https://doi.org/10.3389/feart.2020.00335 2022-12-31T01:37:53Z Coarse blocks are an abundant surface cover in mountainous permafrost landscapes. In this coarse blocky layer, air convection occurs and has a significant influence on the ground thermal regime of the underlying permafrost. Besides heat transfer through conduction, free convection of air takes place seasonally and leads to a pronounced ground cooling. Air convection has been observed and described in many field studies but is often neglected or parametrized in permafrost modeling. In the present study, air convection in the active layer of rock glaciers is explicitly modeled through a heat conduction equation coupled with Darcy’s law over a two-dimensional geometry. With a series of numerical experiments, we show its effects on the thermal regime of the underlying permafrost. The ground permeability and the thermal gradient in the active layer are the most important parameters for air convection in the ground. On field sites with a high ground permeability (order of magnitude 10–6 m2), convection plays a crucial role and is required to correctly model measured borehole temperatures. The onset of natural convection occurs at critical Rayleigh numbers and is characterized by an increase of the standard deviation of the direction and the vorticity of the airflow field in the active layer. In the numerical solutions, the internal air circulation in the coarse blocky surface layer leads to an efficient ground cooling. Article in Journal/Newspaper permafrost Directory of Open Access Journals: DOAJ Articles Frontiers in Earth Science 8 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
rock glacier convection active layer two-dimensional modeling heat transfer permafrost Science Q |
spellingShingle |
rock glacier convection active layer two-dimensional modeling heat transfer permafrost Science Q Jonas Wicky Christian Hauck Air Convection in the Active Layer of Rock Glaciers |
topic_facet |
rock glacier convection active layer two-dimensional modeling heat transfer permafrost Science Q |
description |
Coarse blocks are an abundant surface cover in mountainous permafrost landscapes. In this coarse blocky layer, air convection occurs and has a significant influence on the ground thermal regime of the underlying permafrost. Besides heat transfer through conduction, free convection of air takes place seasonally and leads to a pronounced ground cooling. Air convection has been observed and described in many field studies but is often neglected or parametrized in permafrost modeling. In the present study, air convection in the active layer of rock glaciers is explicitly modeled through a heat conduction equation coupled with Darcy’s law over a two-dimensional geometry. With a series of numerical experiments, we show its effects on the thermal regime of the underlying permafrost. The ground permeability and the thermal gradient in the active layer are the most important parameters for air convection in the ground. On field sites with a high ground permeability (order of magnitude 10–6 m2), convection plays a crucial role and is required to correctly model measured borehole temperatures. The onset of natural convection occurs at critical Rayleigh numbers and is characterized by an increase of the standard deviation of the direction and the vorticity of the airflow field in the active layer. In the numerical solutions, the internal air circulation in the coarse blocky surface layer leads to an efficient ground cooling. |
format |
Article in Journal/Newspaper |
author |
Jonas Wicky Christian Hauck |
author_facet |
Jonas Wicky Christian Hauck |
author_sort |
Jonas Wicky |
title |
Air Convection in the Active Layer of Rock Glaciers |
title_short |
Air Convection in the Active Layer of Rock Glaciers |
title_full |
Air Convection in the Active Layer of Rock Glaciers |
title_fullStr |
Air Convection in the Active Layer of Rock Glaciers |
title_full_unstemmed |
Air Convection in the Active Layer of Rock Glaciers |
title_sort |
air convection in the active layer of rock glaciers |
publisher |
Frontiers Media S.A. |
publishDate |
2020 |
url |
https://doi.org/10.3389/feart.2020.00335 https://doaj.org/article/8aa05bc71226456dba321420e41dcf1b |
genre |
permafrost |
genre_facet |
permafrost |
op_source |
Frontiers in Earth Science, Vol 8 (2020) |
op_relation |
https://www.frontiersin.org/article/10.3389/feart.2020.00335/full https://doaj.org/toc/2296-6463 2296-6463 doi:10.3389/feart.2020.00335 https://doaj.org/article/8aa05bc71226456dba321420e41dcf1b |
op_doi |
https://doi.org/10.3389/feart.2020.00335 |
container_title |
Frontiers in Earth Science |
container_volume |
8 |
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1766164603795931136 |