Using Small Scale Physical Experiments to Improve Enthalpy Based Models of Ice Sheets
Recent work has demonstrated the potential warming influence of meltwater and englacial water bodies on the Greenland Ice Sheet. The equilibrium line has been ascending in altitude, resulting in inland propagation of areas receiving melt. The physical processes involved in the interaction between th...
Main Author: | |
---|---|
Format: | Text |
Language: | unknown |
Published: |
CU Scholar
2013
|
Subjects: | |
Online Access: | https://scholar.colorado.edu/cven_gradetds/316 https://scholar.colorado.edu/cgi/viewcontent.cgi?article=1322&context=cven_gradetds |
id |
ftunicolboulder:oai:scholar.colorado.edu:cven_gradetds-1322 |
---|---|
record_format |
openpolar |
spelling |
ftunicolboulder:oai:scholar.colorado.edu:cven_gradetds-1322 2023-05-15T16:30:30+02:00 Using Small Scale Physical Experiments to Improve Enthalpy Based Models of Ice Sheets Nossokoff, Austin 2013-01-01T08:00:00Z application/pdf https://scholar.colorado.edu/cven_gradetds/316 https://scholar.colorado.edu/cgi/viewcontent.cgi?article=1322&context=cven_gradetds unknown CU Scholar https://scholar.colorado.edu/cven_gradetds/316 https://scholar.colorado.edu/cgi/viewcontent.cgi?article=1322&context=cven_gradetds Civil Engineering Graduate Theses & Dissertations cryo-hydrologic cycle enthalpy friction factor ice sheet meltwater scalloping Civil Engineering Hydrology Physical and Environmental Geography text 2013 ftunicolboulder 2018-10-07T09:10:26Z Recent work has demonstrated the potential warming influence of meltwater and englacial water bodies on the Greenland Ice Sheet. The equilibrium line has been ascending in altitude, resulting in inland propagation of areas receiving melt. The physical processes involved in the interaction between the liquid and solid phases of water within cold ice bodies is not completely understood. This work is meant to improve the understanding of the thermodynamic interactions between englacial water bodies and surrounding ice in polythermal glaciers and ice sheets. The growth of conduits that carry water through the englacial system due to frictional heating along the conduit walls and refreezing when frictional heating is insufficient is studied based on experimental measurements of heat transfer from water filled conduits in cold ice. The important heat exchange processes involved are conductive loss of energy from the conduit and supply of energy by viscous/turbulent dissipation in water flowing through the conduit. [object Object] Three sets of experiments were designed based on a theoretical analysis which established the threshold water discharge rate in a conduit above which conduit growth can occur. One set focused on a conduit filled with stagnant water, another with a low water flow rate, and a third with a high water flow rate. Refreezing occurred in the first two sets, while conduit growth occurred beyond a critical discharge value. Scalloping of conduit walls occurred in the conduit growth regime, leading to a large roughness of conduit walls. Even in the case where refreezing occurs, the ice temperature surrounding the conduit will increase due to the release of latent heat by refreezing water. Using the assumption of radial symmetry, a numerical model was developed to quantify the temperature distribution in the ice. This model represents the conduction and energy supply at the conduit walls by turbulent dissipation and includes movement of the ice-water interface by either refreezing or conduit growth. The scalloping effects under high flow rates produced relatively high friction factors. The model and experiments agree well in all three experimental cases. Text Greenland Ice Sheet University of Colorado, Boulder: CU Scholar Greenland |
institution |
Open Polar |
collection |
University of Colorado, Boulder: CU Scholar |
op_collection_id |
ftunicolboulder |
language |
unknown |
topic |
cryo-hydrologic cycle enthalpy friction factor ice sheet meltwater scalloping Civil Engineering Hydrology Physical and Environmental Geography |
spellingShingle |
cryo-hydrologic cycle enthalpy friction factor ice sheet meltwater scalloping Civil Engineering Hydrology Physical and Environmental Geography Nossokoff, Austin Using Small Scale Physical Experiments to Improve Enthalpy Based Models of Ice Sheets |
topic_facet |
cryo-hydrologic cycle enthalpy friction factor ice sheet meltwater scalloping Civil Engineering Hydrology Physical and Environmental Geography |
description |
Recent work has demonstrated the potential warming influence of meltwater and englacial water bodies on the Greenland Ice Sheet. The equilibrium line has been ascending in altitude, resulting in inland propagation of areas receiving melt. The physical processes involved in the interaction between the liquid and solid phases of water within cold ice bodies is not completely understood. This work is meant to improve the understanding of the thermodynamic interactions between englacial water bodies and surrounding ice in polythermal glaciers and ice sheets. The growth of conduits that carry water through the englacial system due to frictional heating along the conduit walls and refreezing when frictional heating is insufficient is studied based on experimental measurements of heat transfer from water filled conduits in cold ice. The important heat exchange processes involved are conductive loss of energy from the conduit and supply of energy by viscous/turbulent dissipation in water flowing through the conduit. [object Object] Three sets of experiments were designed based on a theoretical analysis which established the threshold water discharge rate in a conduit above which conduit growth can occur. One set focused on a conduit filled with stagnant water, another with a low water flow rate, and a third with a high water flow rate. Refreezing occurred in the first two sets, while conduit growth occurred beyond a critical discharge value. Scalloping of conduit walls occurred in the conduit growth regime, leading to a large roughness of conduit walls. Even in the case where refreezing occurs, the ice temperature surrounding the conduit will increase due to the release of latent heat by refreezing water. Using the assumption of radial symmetry, a numerical model was developed to quantify the temperature distribution in the ice. This model represents the conduction and energy supply at the conduit walls by turbulent dissipation and includes movement of the ice-water interface by either refreezing or conduit growth. The scalloping effects under high flow rates produced relatively high friction factors. The model and experiments agree well in all three experimental cases. |
format |
Text |
author |
Nossokoff, Austin |
author_facet |
Nossokoff, Austin |
author_sort |
Nossokoff, Austin |
title |
Using Small Scale Physical Experiments to Improve Enthalpy Based Models of Ice Sheets |
title_short |
Using Small Scale Physical Experiments to Improve Enthalpy Based Models of Ice Sheets |
title_full |
Using Small Scale Physical Experiments to Improve Enthalpy Based Models of Ice Sheets |
title_fullStr |
Using Small Scale Physical Experiments to Improve Enthalpy Based Models of Ice Sheets |
title_full_unstemmed |
Using Small Scale Physical Experiments to Improve Enthalpy Based Models of Ice Sheets |
title_sort |
using small scale physical experiments to improve enthalpy based models of ice sheets |
publisher |
CU Scholar |
publishDate |
2013 |
url |
https://scholar.colorado.edu/cven_gradetds/316 https://scholar.colorado.edu/cgi/viewcontent.cgi?article=1322&context=cven_gradetds |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Ice Sheet |
genre_facet |
Greenland Ice Sheet |
op_source |
Civil Engineering Graduate Theses & Dissertations |
op_relation |
https://scholar.colorado.edu/cven_gradetds/316 https://scholar.colorado.edu/cgi/viewcontent.cgi?article=1322&context=cven_gradetds |
_version_ |
1766020222783848448 |