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Snow/Firn Densification in Polar Ice Sheets

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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)
Appears in Collections:低温科学 = Low Temperature Science > vol. 68, Supplement Issue

Submitter: 低温科学研究所図書室

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