文章基本信息

标题：Densification of layered firn in the ice sheet at Dome Fuji, Antarctica
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作者：SHUJI FUJITA ; KUMIKO GOTO-AZUMA ; MOTOHIRO HIRABAYASHI 等
期刊名称：Journal of Glaciology
印刷版ISSN：0022-1430
电子版ISSN：1727-5652
出版年度：2016
卷号：62
期号：231
页码：103-123
DOI：10.1017/jog.2016.16
出版社：Cambridge University Press
摘要：ABSTRACT In order to better understand the densification of polar firn, firn cores from the three sites within ~10 km of Dome Fuji, Antarctica, were investigated using surrogates of density: dielectric permittivities ε v and ε h at microwave frequencies with electrical fields in the vertical and horizontal planes respectively. Dielectric anisotropy Δ ε (= ε v − ε h ) was then examined as a surrogate of the anisotropic geometry of firn. We find that layered densification is explained as a result of complex effects of two phenomena that commonly occur at the three sites. Basically, layers with initially smaller density and smaller geometrical anisotropy deform preferentially throughout the densification process due to textural effects. Second, layers having a higher concentration of Cl − ions deform preferentially during a limited period from the near surface depths until smoothing out of layered Cl − ions by diffusion. We hypothesize that Cl − ions dissociated from sea salts soften firn due to modulation of dislocation movement. Moreover, firn differs markedly across the three sites in terms of strength of geometrical anisotropy, mean rate of densification and density fluctuation. We hypothesize that these differences are caused by textural effects resulting from differences in depositional conditions within various spatial scales.
关键词：antarctic glaciology; glacial rheology; ice core; ice physics; polar firn