Numerical modelling of permafrost spring discharge and open-system pingo formation induced by basal permafrost aggradation
In the high Arctic valley of Adventdalen, Svalbard, sub-permafrost groundwater feeds several pingo springs distributed along the valley axis. The driving mechanism for groundwater discharge and associated pingo formation is enigmatic because wet-based glaciers are not present in the adjacent highlan...
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Online Access: | https://hdl.handle.net/11250/2733542 https://doi.org/10.5194/tc-14-4627-2020 |
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fthsvestlandet:oai:hvlopen.brage.unit.no:11250/2733542 2024-03-03T08:36:14+00:00 Numerical modelling of permafrost spring discharge and open-system pingo formation induced by basal permafrost aggradation Hornum, Mikkel Toft Hodson, Andrew Jessen, Søren Bense, Victor Senger, Kim 2020 application/pdf https://hdl.handle.net/11250/2733542 https://doi.org/10.5194/tc-14-4627-2020 eng eng Copernicus Publications Hornum, M. T., Hodson, A. J., Jessen, S., Bense, V., & Senger, K. (2020). Numerical modelling of permafrost spring discharge and open-system pingo formation induced by basal permafrost aggradation. The Cryosphere, 14 (12), 4627-4651. urn:issn:1994-0416 https://hdl.handle.net/11250/2733542 https://doi.org/10.5194/tc-14-4627-2020 cristin:1869498 Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no © Author(s) 2020. 4627-4651 14 The Cryosphere 12 Journal article Peer reviewed 2020 fthsvestlandet https://doi.org/10.5194/tc-14-4627-2020 2024-02-02T12:40:45Z In the high Arctic valley of Adventdalen, Svalbard, sub-permafrost groundwater feeds several pingo springs distributed along the valley axis. The driving mechanism for groundwater discharge and associated pingo formation is enigmatic because wet-based glaciers are not present in the adjacent highlands and the presence of continuous permafrost seems to preclude recharge of the sub-permafrost groundwater system by either a subglacial source or a precipitation surplus. Since the pingo springs enable methane that has accumulated underneath the permafrost to escape directly to the atmosphere, our limited understanding of the groundwater system brings significant uncertainty to predictions of how methane emissions will respond to changing climate. We address this problem with a new conceptual model for open-system pingo formation wherein pingo growth is sustained by sub-permafrost pressure effects, as related to the expansion of water upon freezing, during millennial-scale basal permafrost aggradation. We test the viability of this mechanism for generating groundwater flow with decoupled heat (one-dimensional transient) and groundwater (three-dimensional steady state) transport modelling experiments. Our results suggest that the conceptual model represents a feasible mechanism for the formation of open-system pingos in lower Adventdalen and elsewhere. We also explore the potential for additional pressurisation and find that methane production and methane clathrate formation and dissolution deserve particular attention on account of their likely effects upon the hydraulic pressure. Our model simulations also suggest that the generally low-permeability hydrogeological units cause groundwater residence times to exceed the duration of the Holocene. The likelihood of such pre-Holocene groundwater ages is supported by the geochemistry of the pingo springs which demonstrates an unexpected seaward freshening of groundwater potentially caused by a palaeo-subglacial meltwater “wedge” from the Weichselian. Whereas permafrost ... Article in Journal/Newspaper Adventdalen Arctic open system Pingo permafrost Svalbard The Cryosphere wedge* Høgskulen på Vestlandet: HVL Open Arctic Svalbard Adventdalen ENVELOPE(16.264,16.264,78.181,78.181) The Cryosphere 14 12 4627 4651 |
institution |
Open Polar |
collection |
Høgskulen på Vestlandet: HVL Open |
op_collection_id |
fthsvestlandet |
language |
English |
description |
In the high Arctic valley of Adventdalen, Svalbard, sub-permafrost groundwater feeds several pingo springs distributed along the valley axis. The driving mechanism for groundwater discharge and associated pingo formation is enigmatic because wet-based glaciers are not present in the adjacent highlands and the presence of continuous permafrost seems to preclude recharge of the sub-permafrost groundwater system by either a subglacial source or a precipitation surplus. Since the pingo springs enable methane that has accumulated underneath the permafrost to escape directly to the atmosphere, our limited understanding of the groundwater system brings significant uncertainty to predictions of how methane emissions will respond to changing climate. We address this problem with a new conceptual model for open-system pingo formation wherein pingo growth is sustained by sub-permafrost pressure effects, as related to the expansion of water upon freezing, during millennial-scale basal permafrost aggradation. We test the viability of this mechanism for generating groundwater flow with decoupled heat (one-dimensional transient) and groundwater (three-dimensional steady state) transport modelling experiments. Our results suggest that the conceptual model represents a feasible mechanism for the formation of open-system pingos in lower Adventdalen and elsewhere. We also explore the potential for additional pressurisation and find that methane production and methane clathrate formation and dissolution deserve particular attention on account of their likely effects upon the hydraulic pressure. Our model simulations also suggest that the generally low-permeability hydrogeological units cause groundwater residence times to exceed the duration of the Holocene. The likelihood of such pre-Holocene groundwater ages is supported by the geochemistry of the pingo springs which demonstrates an unexpected seaward freshening of groundwater potentially caused by a palaeo-subglacial meltwater “wedge” from the Weichselian. Whereas permafrost ... |
format |
Article in Journal/Newspaper |
author |
Hornum, Mikkel Toft Hodson, Andrew Jessen, Søren Bense, Victor Senger, Kim |
spellingShingle |
Hornum, Mikkel Toft Hodson, Andrew Jessen, Søren Bense, Victor Senger, Kim Numerical modelling of permafrost spring discharge and open-system pingo formation induced by basal permafrost aggradation |
author_facet |
Hornum, Mikkel Toft Hodson, Andrew Jessen, Søren Bense, Victor Senger, Kim |
author_sort |
Hornum, Mikkel Toft |
title |
Numerical modelling of permafrost spring discharge and open-system pingo formation induced by basal permafrost aggradation |
title_short |
Numerical modelling of permafrost spring discharge and open-system pingo formation induced by basal permafrost aggradation |
title_full |
Numerical modelling of permafrost spring discharge and open-system pingo formation induced by basal permafrost aggradation |
title_fullStr |
Numerical modelling of permafrost spring discharge and open-system pingo formation induced by basal permafrost aggradation |
title_full_unstemmed |
Numerical modelling of permafrost spring discharge and open-system pingo formation induced by basal permafrost aggradation |
title_sort |
numerical modelling of permafrost spring discharge and open-system pingo formation induced by basal permafrost aggradation |
publisher |
Copernicus Publications |
publishDate |
2020 |
url |
https://hdl.handle.net/11250/2733542 https://doi.org/10.5194/tc-14-4627-2020 |
long_lat |
ENVELOPE(16.264,16.264,78.181,78.181) |
geographic |
Arctic Svalbard Adventdalen |
geographic_facet |
Arctic Svalbard Adventdalen |
genre |
Adventdalen Arctic open system Pingo permafrost Svalbard The Cryosphere wedge* |
genre_facet |
Adventdalen Arctic open system Pingo permafrost Svalbard The Cryosphere wedge* |
op_source |
4627-4651 14 The Cryosphere 12 |
op_relation |
Hornum, M. T., Hodson, A. J., Jessen, S., Bense, V., & Senger, K. (2020). Numerical modelling of permafrost spring discharge and open-system pingo formation induced by basal permafrost aggradation. The Cryosphere, 14 (12), 4627-4651. urn:issn:1994-0416 https://hdl.handle.net/11250/2733542 https://doi.org/10.5194/tc-14-4627-2020 cristin:1869498 |
op_rights |
Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no © Author(s) 2020. |
op_doi |
https://doi.org/10.5194/tc-14-4627-2020 |
container_title |
The Cryosphere |
container_volume |
14 |
container_issue |
12 |
container_start_page |
4627 |
op_container_end_page |
4651 |
_version_ |
1792496228469047296 |