Thermal Convection in Ice Sheets: We Look But Do Not See
Thermal convection in the Antarctic and Greenland ice sheets has been dismissed on the grounds that radio-echo stratigraphy is undisturbed for long distances. However, the undisturbed stratigraphy lies, for the most part, above the density inversion in polar ice sheets and therefore does not disprov...
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ftmaineuniv:oai:digitalcommons.library.umaine.edu:ers_facpub-1109 2024-09-15T17:46:28+00:00 Thermal Convection in Ice Sheets: We Look But Do Not See Hughes, Terence J. 1985-01-01T08:00:00Z application/pdf https://digitalcommons.library.umaine.edu/ers_facpub/110 https://digitalcommons.library.umaine.edu/context/ers_facpub/article/1109/viewcontent/hughes_31.107.39.pdf unknown DigitalCommons@UMaine https://digitalcommons.library.umaine.edu/ers_facpub/110 https://digitalcommons.library.umaine.edu/context/ers_facpub/article/1109/viewcontent/hughes_31.107.39.pdf This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. In addition, no permission is required from the rights-holder(s) for educational uses. For other uses, you need to obtain permission from the rights-holder(s). Earth Science Faculty Scholarship Earth Sciences text 1985 ftmaineuniv 2024-07-24T05:38:40Z Thermal convection in the Antarctic and Greenland ice sheets has been dismissed on the grounds that radio-echo stratigraphy is undisturbed for long distances. However, the undisturbed stratigraphy lies, for the most part, above the density inversion in polar ice sheets and therefore does not disprove convection. An echo-free zone is widespread below the density inversion, yet nobody has cited this as a strong indication that convection is indeed present at d�pth. A generalized Rayleigh criterion for thermal convection in e1astic-viscoplastic polycrystalline solids heated from below is developed and applied to ice-sheet convection. An infinite Rayleigh number at the onset of primary creep decreases with time and becomes constant when secondary creep dominates, suggesting that any thermal buoyancy stress can initiate convection but convection cannot be sustained below a buoyancy stress of about 3 kPa. An analysis of the temperature profile down the Byrd Station core hole suggests that about 1000 m of ice below the density inversion will sustain convection. Creep along the Byrd Station strain network, radar sounding in East Antarctica, and seismic sounding in West Antarctica are examined for evidence of convective creep superimposed on advective creep. It is concluded that the evidence for convection is there, if we look for it with the intention offinding it. Text Antarc* Antarctic Antarctica East Antarctica Greenland Ice Sheet West Antarctica The University of Maine: DigitalCommons@UMaine |
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Earth Sciences |
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Earth Sciences Hughes, Terence J. Thermal Convection in Ice Sheets: We Look But Do Not See |
topic_facet |
Earth Sciences |
description |
Thermal convection in the Antarctic and Greenland ice sheets has been dismissed on the grounds that radio-echo stratigraphy is undisturbed for long distances. However, the undisturbed stratigraphy lies, for the most part, above the density inversion in polar ice sheets and therefore does not disprove convection. An echo-free zone is widespread below the density inversion, yet nobody has cited this as a strong indication that convection is indeed present at d�pth. A generalized Rayleigh criterion for thermal convection in e1astic-viscoplastic polycrystalline solids heated from below is developed and applied to ice-sheet convection. An infinite Rayleigh number at the onset of primary creep decreases with time and becomes constant when secondary creep dominates, suggesting that any thermal buoyancy stress can initiate convection but convection cannot be sustained below a buoyancy stress of about 3 kPa. An analysis of the temperature profile down the Byrd Station core hole suggests that about 1000 m of ice below the density inversion will sustain convection. Creep along the Byrd Station strain network, radar sounding in East Antarctica, and seismic sounding in West Antarctica are examined for evidence of convective creep superimposed on advective creep. It is concluded that the evidence for convection is there, if we look for it with the intention offinding it. |
format |
Text |
author |
Hughes, Terence J. |
author_facet |
Hughes, Terence J. |
author_sort |
Hughes, Terence J. |
title |
Thermal Convection in Ice Sheets: We Look But Do Not See |
title_short |
Thermal Convection in Ice Sheets: We Look But Do Not See |
title_full |
Thermal Convection in Ice Sheets: We Look But Do Not See |
title_fullStr |
Thermal Convection in Ice Sheets: We Look But Do Not See |
title_full_unstemmed |
Thermal Convection in Ice Sheets: We Look But Do Not See |
title_sort |
thermal convection in ice sheets: we look but do not see |
publisher |
DigitalCommons@UMaine |
publishDate |
1985 |
url |
https://digitalcommons.library.umaine.edu/ers_facpub/110 https://digitalcommons.library.umaine.edu/context/ers_facpub/article/1109/viewcontent/hughes_31.107.39.pdf |
genre |
Antarc* Antarctic Antarctica East Antarctica Greenland Ice Sheet West Antarctica |
genre_facet |
Antarc* Antarctic Antarctica East Antarctica Greenland Ice Sheet West Antarctica |
op_source |
Earth Science Faculty Scholarship |
op_relation |
https://digitalcommons.library.umaine.edu/ers_facpub/110 https://digitalcommons.library.umaine.edu/context/ers_facpub/article/1109/viewcontent/hughes_31.107.39.pdf |
op_rights |
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. In addition, no permission is required from the rights-holder(s) for educational uses. For other uses, you need to obtain permission from the rights-holder(s). |
_version_ |
1810494616987762688 |