Microtopographic control on the ground thermal regime in ice wedge polygons
The goal of this research is to constrain the influence of ice wedge polygon microtopography on near-surface ground temperatures. Ice wedge polygon microtopography is prone to rapid deformation in a changing climate, and cracking in the ice wedge depends on thermal conditions at the top of the perma...
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Online Access: | http://www.osti.gov/servlets/purl/1463489 https://www.osti.gov/biblio/1463489 https://doi.org/10.5194/tc-12-1957-2018 |
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ftosti:oai:osti.gov:1463489 2023-07-30T04:02:09+02:00 Microtopographic control on the ground thermal regime in ice wedge polygons Abolt, Charles J. Young, Michael H. Atchley, Adam L. Harp, Dylan R. 2023-06-28 application/pdf http://www.osti.gov/servlets/purl/1463489 https://www.osti.gov/biblio/1463489 https://doi.org/10.5194/tc-12-1957-2018 unknown http://www.osti.gov/servlets/purl/1463489 https://www.osti.gov/biblio/1463489 https://doi.org/10.5194/tc-12-1957-2018 doi:10.5194/tc-12-1957-2018 58 GEOSCIENCES 2023 ftosti https://doi.org/10.5194/tc-12-1957-2018 2023-07-11T09:28:05Z The goal of this research is to constrain the influence of ice wedge polygon microtopography on near-surface ground temperatures. Ice wedge polygon microtopography is prone to rapid deformation in a changing climate, and cracking in the ice wedge depends on thermal conditions at the top of the permafrost; therefore, feedbacks between microtopography and ground temperature can shed light on the potential for future ice wedge cracking in the Arctic. We first report on a year of sub-daily ground temperature observations at 5 depths and 9 locations throughout a cluster of low-centered polygons near Prudhoe Bay, Alaska, and demonstrate that the rims become the coldest zone of the polygon during winter, due to thinner snowpack. We then calibrate a polygon-scale numerical model of coupled thermal and hydrologic processes against this dataset, achieving an RMSE of less than 1.1 °C between observed and simulated ground temperature. Finally, we conduct a sensitivity analysis of the model by systematically manipulating the height of the rims and the depth of the troughs and tracking the effects on ice wedge temperature. The results indicate that winter temperatures in the ice wedge are sensitive to both rim height and trough depth, but more sensitive to rim height. Rims act as preferential outlets of subsurface heat; increasing rim size decreases winter temperatures in the ice wedge. Deeper troughs lead to increased snow entrapment, promoting insulation of the ice wedge. The potential for ice wedge cracking is therefore reduced if rims are destroyed or if troughs subside, due to warmer conditions in the ice wedge. These findings can help explain the origins of secondary ice wedges in modern and ancient polygons. The findings also imply that the potential for re-establishing rims in modern thermokarst-affected terrain will be limited by reduced cracking activity in the ice wedges, even if regional air temperatures stabilize. Other/Unknown Material Arctic Ice permafrost Prudhoe Bay Thermokarst wedge* Alaska SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) Arctic The Cryosphere 12 6 1957 1968 |
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SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) |
op_collection_id |
ftosti |
language |
unknown |
topic |
58 GEOSCIENCES |
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58 GEOSCIENCES Abolt, Charles J. Young, Michael H. Atchley, Adam L. Harp, Dylan R. Microtopographic control on the ground thermal regime in ice wedge polygons |
topic_facet |
58 GEOSCIENCES |
description |
The goal of this research is to constrain the influence of ice wedge polygon microtopography on near-surface ground temperatures. Ice wedge polygon microtopography is prone to rapid deformation in a changing climate, and cracking in the ice wedge depends on thermal conditions at the top of the permafrost; therefore, feedbacks between microtopography and ground temperature can shed light on the potential for future ice wedge cracking in the Arctic. We first report on a year of sub-daily ground temperature observations at 5 depths and 9 locations throughout a cluster of low-centered polygons near Prudhoe Bay, Alaska, and demonstrate that the rims become the coldest zone of the polygon during winter, due to thinner snowpack. We then calibrate a polygon-scale numerical model of coupled thermal and hydrologic processes against this dataset, achieving an RMSE of less than 1.1 °C between observed and simulated ground temperature. Finally, we conduct a sensitivity analysis of the model by systematically manipulating the height of the rims and the depth of the troughs and tracking the effects on ice wedge temperature. The results indicate that winter temperatures in the ice wedge are sensitive to both rim height and trough depth, but more sensitive to rim height. Rims act as preferential outlets of subsurface heat; increasing rim size decreases winter temperatures in the ice wedge. Deeper troughs lead to increased snow entrapment, promoting insulation of the ice wedge. The potential for ice wedge cracking is therefore reduced if rims are destroyed or if troughs subside, due to warmer conditions in the ice wedge. These findings can help explain the origins of secondary ice wedges in modern and ancient polygons. The findings also imply that the potential for re-establishing rims in modern thermokarst-affected terrain will be limited by reduced cracking activity in the ice wedges, even if regional air temperatures stabilize. |
author |
Abolt, Charles J. Young, Michael H. Atchley, Adam L. Harp, Dylan R. |
author_facet |
Abolt, Charles J. Young, Michael H. Atchley, Adam L. Harp, Dylan R. |
author_sort |
Abolt, Charles J. |
title |
Microtopographic control on the ground thermal regime in ice wedge polygons |
title_short |
Microtopographic control on the ground thermal regime in ice wedge polygons |
title_full |
Microtopographic control on the ground thermal regime in ice wedge polygons |
title_fullStr |
Microtopographic control on the ground thermal regime in ice wedge polygons |
title_full_unstemmed |
Microtopographic control on the ground thermal regime in ice wedge polygons |
title_sort |
microtopographic control on the ground thermal regime in ice wedge polygons |
publishDate |
2023 |
url |
http://www.osti.gov/servlets/purl/1463489 https://www.osti.gov/biblio/1463489 https://doi.org/10.5194/tc-12-1957-2018 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Ice permafrost Prudhoe Bay Thermokarst wedge* Alaska |
genre_facet |
Arctic Ice permafrost Prudhoe Bay Thermokarst wedge* Alaska |
op_relation |
http://www.osti.gov/servlets/purl/1463489 https://www.osti.gov/biblio/1463489 https://doi.org/10.5194/tc-12-1957-2018 doi:10.5194/tc-12-1957-2018 |
op_doi |
https://doi.org/10.5194/tc-12-1957-2018 |
container_title |
The Cryosphere |
container_volume |
12 |
container_issue |
6 |
container_start_page |
1957 |
op_container_end_page |
1968 |
_version_ |
1772812877741162496 |