Bubbly-ice densification in ice sheets: II. Applications
A mathematical model for simulating the densification of bubbly glacier ice is used to interpret the following experimental data from the Vostok (central Antarctica) ice core: two ice-porosity profiles obtained by independent methods and a bubble-pressure profile obtained by direct measurements of a...
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ftkazanuniv:oai:dspace.kpfu.ru:net/133404 2023-05-15T14:03:54+02:00 Bubbly-ice densification in ice sheets: II. Applications Lipenkov V. Salamatin A. Duval P. 1997 https://dspace.kpfu.ru/xmlui/handle/net/133404 unknown Journal of Glaciology 145 43 397 http://dspace.kpfu.ru/xmlui/bitstream/net/133404/-1/SCOPUS00221430-1997-43-145-SID0031401612-a1.pdf 0022-1430 https://dspace.kpfu.ru/xmlui/handle/net/133404 SCOPUS00221430-1997-43-145-SID0031401612 Article 1997 ftkazanuniv 2022-01-01T09:45:26Z A mathematical model for simulating the densification of bubbly glacier ice is used to interpret the following experimental data from the Vostok (central Antarctica) ice core: two ice-porosity profiles obtained by independent methods and a bubble-pressure profile obtained by direct measurements of air pressure within individual bubbles. The rheological properties of pure polycrystalline ice are deduced from the solution of the inverse problem. The model and the inferred ice-flow law are then validated, using porosity profiles from seven other ice cores drilled in Antarctica and Greenland, in the temperature range from -55° to -20°C. The following expression is adopted for the constitutive law: 2ė = (τ/μ1 + τα/μ2) exp[Q(1/Ts - 1/T)/Rs] where ė and τ are the effective strain rate and stress, respectively, α is the creep exponent taken as 3.5, Rs is the gas constant and T(Ts) is the temperature (standard temperature). The numerical values obtained for the "linear" and "non-linear" viscosities are: μ1 = 2.9 ± 1.3 MPa year and μ2 = 0.051 ± 0.019 MPaα year, and the apparent activation energy Q is confirmed to be 60 kj mole-1. The corresponding flow law is in good agreement with results of both mechanical tests and independent estimations based on the analysis of different natural phenomena associated with glacier-ice deformation. When the model is constrained by the porosity and bubble-pressure profiles from Vostok, the mean air content in Holocene ice is inferred to be about 0.088 cm3g-1. The corresponding mean air pressure in bubbles at the end of pore closure is about 0.083 MPa, whereas the atmospheric pressure at this depth level would be 0.063 MPa. The influence of the climatic change on the ice-porosity profile is discussed. It resulted in an increased air content in ice at Vostok during the Last Glacial Maximum: 0.096 cm3g-1. Article in Journal/Newspaper Antarc* Antarctica glacier Greenland ice core Journal of Glaciology Kazan Federal University Digital Repository Greenland |
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Kazan Federal University Digital Repository |
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description |
A mathematical model for simulating the densification of bubbly glacier ice is used to interpret the following experimental data from the Vostok (central Antarctica) ice core: two ice-porosity profiles obtained by independent methods and a bubble-pressure profile obtained by direct measurements of air pressure within individual bubbles. The rheological properties of pure polycrystalline ice are deduced from the solution of the inverse problem. The model and the inferred ice-flow law are then validated, using porosity profiles from seven other ice cores drilled in Antarctica and Greenland, in the temperature range from -55° to -20°C. The following expression is adopted for the constitutive law: 2ė = (τ/μ1 + τα/μ2) exp[Q(1/Ts - 1/T)/Rs] where ė and τ are the effective strain rate and stress, respectively, α is the creep exponent taken as 3.5, Rs is the gas constant and T(Ts) is the temperature (standard temperature). The numerical values obtained for the "linear" and "non-linear" viscosities are: μ1 = 2.9 ± 1.3 MPa year and μ2 = 0.051 ± 0.019 MPaα year, and the apparent activation energy Q is confirmed to be 60 kj mole-1. The corresponding flow law is in good agreement with results of both mechanical tests and independent estimations based on the analysis of different natural phenomena associated with glacier-ice deformation. When the model is constrained by the porosity and bubble-pressure profiles from Vostok, the mean air content in Holocene ice is inferred to be about 0.088 cm3g-1. The corresponding mean air pressure in bubbles at the end of pore closure is about 0.083 MPa, whereas the atmospheric pressure at this depth level would be 0.063 MPa. The influence of the climatic change on the ice-porosity profile is discussed. It resulted in an increased air content in ice at Vostok during the Last Glacial Maximum: 0.096 cm3g-1. |
format |
Article in Journal/Newspaper |
author |
Lipenkov V. Salamatin A. Duval P. |
spellingShingle |
Lipenkov V. Salamatin A. Duval P. Bubbly-ice densification in ice sheets: II. Applications |
author_facet |
Lipenkov V. Salamatin A. Duval P. |
author_sort |
Lipenkov V. |
title |
Bubbly-ice densification in ice sheets: II. Applications |
title_short |
Bubbly-ice densification in ice sheets: II. Applications |
title_full |
Bubbly-ice densification in ice sheets: II. Applications |
title_fullStr |
Bubbly-ice densification in ice sheets: II. Applications |
title_full_unstemmed |
Bubbly-ice densification in ice sheets: II. Applications |
title_sort |
bubbly-ice densification in ice sheets: ii. applications |
publishDate |
1997 |
url |
https://dspace.kpfu.ru/xmlui/handle/net/133404 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Antarc* Antarctica glacier Greenland ice core Journal of Glaciology |
genre_facet |
Antarc* Antarctica glacier Greenland ice core Journal of Glaciology |
op_source |
SCOPUS00221430-1997-43-145-SID0031401612 |
op_relation |
Journal of Glaciology 145 43 397 http://dspace.kpfu.ru/xmlui/bitstream/net/133404/-1/SCOPUS00221430-1997-43-145-SID0031401612-a1.pdf 0022-1430 https://dspace.kpfu.ru/xmlui/handle/net/133404 |
_version_ |
1766274763246796800 |