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Hokkaido University Collection of Scholarly and Academic Papers >
Institute of Low Temperature Science >
低温科学 = Low Temperature Science >
vol. 68, Supplement Issue >
Snow/Firn Densification in Polar Ice Sheets
| Title: | Snow/Firn Densification in Polar Ice Sheets |
| Authors: | Salamatin, Andrey N. Browse this author | | Lipenkov, Vladimir Ya. Browse this author | | Barnola, Jean Marc Browse this author | | Hori, Akira Browse this author | | Duval, Paul Browse this author | | Hondoh, Takeo Browse this author |
| Keywords: | ice sheet | | snow/firn densification | | physical model | | paleoclimatic implication |
| Issue Date: | Dec-2009 |
| Publisher: | Institute of Low Temperature Science, Hokkaido University |
| Citation: | Physics of Ice Core Records II : Papers collected after the 2nd International Workshop on Physics of Ice Core Records, held in Sapporo, Japan, 2-6 February 2007. Edited by Takeo Hondoh |
| Journal Title: | 低温科学 |
| Journal Title(alt): | Low Temperature Science |
| Volume: | 68 |
| Issue: | Supplement |
| Start Page: | 195 |
| End Page: | 222 |
| Abstract: | A sophisticated physical model of the dry snow/firn densification process in ice sheets is proposed. Macroscopically, snow and firn undergo vertical uniaxial compression with non-zero deviatoric stresses and strain rates. The present mathematical description of densificntion includes dilatancy and "force-chain" effects in snow and develops previous concepts of ice-particle rearrangement by grain-boundary sliding and sintering by power-law creep under overburden pressure. Both densification mechanisms work together during the first snow stage until the closest packing of ice grains is reached at critical densities of 0.7-0.76 and the firn stage controlled only by the dislocation creep sets on. In addition to the ice-grain coordination number and the slope of the radial distribution function, a new structural parameter is introduced to account for grain bonding (agglomeration) effects. The model is constrained and validated on direct stereological observations of ice core structures and a representative set of snow/firn density-depth profiles covering a wide range of present-day climatic conditions (-57.5 to -10℃ and ice accumulation at 2.15 to 330 cm yr^[-1] ). Simple equations are derived for predicting the depth of pore closure in firn and the ice age at close-off. The paleoclimatic evolution of quasi-stationary density-depth profiles and close-off characteristics at Vostok Station (East Antarctica) are simulated and discussed. |
| Description: | III. Firn densification, close-off and chronology |
| Type: | bulletin (article) |
| URI: | http://hdl.handle.net/2115/45449 |
| Appears in Collections: | 低温科学 = Low Temperature Science > vol. 68, Supplement Issue
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Submitter: 低温科学研究所図書室
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