Thermal tracking of meltwater retention in Greenland’s accumulation area
Poorly understood processes controlling retention of meltwater in snow and firn have important implications for Greenland Ice Sheet’s mass balance and flow dynamics. Here we present results from a 3 year (2007-2009) field campaign studying firn thermal profiles and density structure along an 85 km...
Published in: | Journal of Geophysical Research: Earth Surface |
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ScholarWorks at University of Montana
2012
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Online Access: | https://scholarworks.umt.edu/geosci_pubs/13 https://doi.org/10.1029/2011JF002083 https://scholarworks.umt.edu/context/geosci_pubs/article/1017/viewcontent/Humphrey_et_al_2012_Journal_of_Geophysical_Research__Earth_Surface__2003_2012_.pdf https://scholarworks.umt.edu/context/geosci_pubs/article/1017/filename/0/type/additional/viewcontent/Suppl._Thermal_tracking_of_meltwater_retention_in_Greenland_s_accumulation_area.pdf |
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ftunivmontana:oai:scholarworks.umt.edu:geosci_pubs-1017 2024-09-09T19:43:09+00:00 Thermal tracking of meltwater retention in Greenland’s accumulation area Humphrey, Neil F. Harper, Joel T. Pfeffer, W. Tad 2012-01-25T08:00:00Z application/pdf https://scholarworks.umt.edu/geosci_pubs/13 https://doi.org/10.1029/2011JF002083 https://scholarworks.umt.edu/context/geosci_pubs/article/1017/viewcontent/Humphrey_et_al_2012_Journal_of_Geophysical_Research__Earth_Surface__2003_2012_.pdf https://scholarworks.umt.edu/context/geosci_pubs/article/1017/filename/0/type/additional/viewcontent/Suppl._Thermal_tracking_of_meltwater_retention_in_Greenland_s_accumulation_area.pdf unknown ScholarWorks at University of Montana https://scholarworks.umt.edu/geosci_pubs/13 doi:10.1029/2011JF002083 https://scholarworks.umt.edu/context/geosci_pubs/article/1017/viewcontent/Humphrey_et_al_2012_Journal_of_Geophysical_Research__Earth_Surface__2003_2012_.pdf https://scholarworks.umt.edu/context/geosci_pubs/article/1017/filename/0/type/additional/viewcontent/Suppl._Thermal_tracking_of_meltwater_retention_in_Greenland_s_accumulation_area.pdf © 2012. American Geophysical Union. Geosciences Faculty Publications Earth Sciences Geology text 2012 ftunivmontana https://doi.org/10.1029/2011JF002083 2024-06-20T05:32:53Z Poorly understood processes controlling retention of meltwater in snow and firn have important implications for Greenland Ice Sheet’s mass balance and flow dynamics. Here we present results from a 3 year (2007-2009) field campaign studying firn thermal profiles and density structure along an 85 km transect of the percolation zone of west Greenland. We installed one or two thermistor strings at 14 study sites, each string having 32 sensors spaced between 0 and 10 m depth. Data from our network of over 500 sensors were collected at 15-60 min intervals for 1-2 years, thereby recording the thermal signature of meltwater infiltration and refreezing during annual melt cycles. We document three types of heating of firn related to different mechanisms of meltwater motion and freezing, including heterogeneous breakthrough events, wetting front advance, and year-round heating from freezing of residual deep pore water. Vertically infiltrating meltwater commonly penetrates through cold firn accumulated over decades, even where ice layers are present at the previous summer surface and where ice layer thickness exceeds several decimeters. The offset between the mean annual air temperature and the 10 m firn temperature reveals the elevation dependency of meltwater retention along our transect. The firn is less than 10 degrees C warmer than the mean annual air temperature at the region where meltwater runoff initiates. During 2007-2009, runoff was limited to elevations lower than about 1500 m with no sharp "runoff limit"; rather, the ratio of retention to runoff transitioned from all retention to all runoff across an about 20 km wide zone. Text Greenland University of Montana: ScholarWorks Greenland Journal of Geophysical Research: Earth Surface 117 F1 n/a n/a |
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University of Montana: ScholarWorks |
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ftunivmontana |
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topic |
Earth Sciences Geology |
spellingShingle |
Earth Sciences Geology Humphrey, Neil F. Harper, Joel T. Pfeffer, W. Tad Thermal tracking of meltwater retention in Greenland’s accumulation area |
topic_facet |
Earth Sciences Geology |
description |
Poorly understood processes controlling retention of meltwater in snow and firn have important implications for Greenland Ice Sheet’s mass balance and flow dynamics. Here we present results from a 3 year (2007-2009) field campaign studying firn thermal profiles and density structure along an 85 km transect of the percolation zone of west Greenland. We installed one or two thermistor strings at 14 study sites, each string having 32 sensors spaced between 0 and 10 m depth. Data from our network of over 500 sensors were collected at 15-60 min intervals for 1-2 years, thereby recording the thermal signature of meltwater infiltration and refreezing during annual melt cycles. We document three types of heating of firn related to different mechanisms of meltwater motion and freezing, including heterogeneous breakthrough events, wetting front advance, and year-round heating from freezing of residual deep pore water. Vertically infiltrating meltwater commonly penetrates through cold firn accumulated over decades, even where ice layers are present at the previous summer surface and where ice layer thickness exceeds several decimeters. The offset between the mean annual air temperature and the 10 m firn temperature reveals the elevation dependency of meltwater retention along our transect. The firn is less than 10 degrees C warmer than the mean annual air temperature at the region where meltwater runoff initiates. During 2007-2009, runoff was limited to elevations lower than about 1500 m with no sharp "runoff limit"; rather, the ratio of retention to runoff transitioned from all retention to all runoff across an about 20 km wide zone. |
format |
Text |
author |
Humphrey, Neil F. Harper, Joel T. Pfeffer, W. Tad |
author_facet |
Humphrey, Neil F. Harper, Joel T. Pfeffer, W. Tad |
author_sort |
Humphrey, Neil F. |
title |
Thermal tracking of meltwater retention in Greenland’s accumulation area |
title_short |
Thermal tracking of meltwater retention in Greenland’s accumulation area |
title_full |
Thermal tracking of meltwater retention in Greenland’s accumulation area |
title_fullStr |
Thermal tracking of meltwater retention in Greenland’s accumulation area |
title_full_unstemmed |
Thermal tracking of meltwater retention in Greenland’s accumulation area |
title_sort |
thermal tracking of meltwater retention in greenland’s accumulation area |
publisher |
ScholarWorks at University of Montana |
publishDate |
2012 |
url |
https://scholarworks.umt.edu/geosci_pubs/13 https://doi.org/10.1029/2011JF002083 https://scholarworks.umt.edu/context/geosci_pubs/article/1017/viewcontent/Humphrey_et_al_2012_Journal_of_Geophysical_Research__Earth_Surface__2003_2012_.pdf https://scholarworks.umt.edu/context/geosci_pubs/article/1017/filename/0/type/additional/viewcontent/Suppl._Thermal_tracking_of_meltwater_retention_in_Greenland_s_accumulation_area.pdf |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Geosciences Faculty Publications |
op_relation |
https://scholarworks.umt.edu/geosci_pubs/13 doi:10.1029/2011JF002083 https://scholarworks.umt.edu/context/geosci_pubs/article/1017/viewcontent/Humphrey_et_al_2012_Journal_of_Geophysical_Research__Earth_Surface__2003_2012_.pdf https://scholarworks.umt.edu/context/geosci_pubs/article/1017/filename/0/type/additional/viewcontent/Suppl._Thermal_tracking_of_meltwater_retention_in_Greenland_s_accumulation_area.pdf |
op_rights |
© 2012. American Geophysical Union. |
op_doi |
https://doi.org/10.1029/2011JF002083 |
container_title |
Journal of Geophysical Research: Earth Surface |
container_volume |
117 |
container_issue |
F1 |
container_start_page |
n/a |
op_container_end_page |
n/a |
_version_ |
1809912486205325312 |