气候变化领域集成服务门户(CCPortal): Using a composite flow law to model deformation in the NEEM deep ice core, Greenland-Part 2: The role of grain size and premelting on ice deformation at high homologous temperature

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DOI	10.5194/tc-14-2449-2020
	Using a composite flow law to model deformation in the NEEM deep ice core, Greenland-Part 2: The role of grain size and premelting on ice deformation at high homologous temperature
	Kuiper E.-J.N.; De Bresser J.H.P.; Drury M.R.; Eichler J.; Pennock G.M.; Weikusat I.
发表日期	2020
ISSN	19940416
起始页码	2449
结束页码	2467
卷号	14 期号:7
英文摘要	The ice microstructure in the lower part of the North Greenland Eemian Ice Drilling (NEEM) ice core consists of relatively fine-grained ice with a single maximum crystallographic preferred orientation (CPO) alternated by much coarser-grained ice with a partial (great circle) girdle or multi-maxima CPO. In this study, the grain-size-sensitive (GSS) composite flow law of Goldsby and Kohlstedt (2001) was used to study the effects of grain size and premelting (liquid-like layer along the grain boundaries) on strain rate in the lower part of the NEEM ice core. The results show that the strain rates predicted in the fine-grained layers are about an order of magnitude higher than in the much coarser-grained layers. The dominant deformation mechanisms, based on the flow relation of Goldsby and Kohlstedt (2001), between the layers is also different, with basal slip rate limited by grain boundary sliding (GBS-limited creep) being the dominant deformation mechanism in the finer-grained layers, while GBS-limited creep and dislocation creep (basal slip rate limited by non-basal slip) contribute both roughly equally to bulk strain in the coarsegrained layers. Due to the large difference in microstructure between finer-grained ice and the coarse-grained ice at premelting temperatures (T > 262 K), it is expected that the fine-grained layers deform at high strain rates, while the coarse-grained layers are relatively stagnant. The difference in microstructure, and consequently in viscosity, between impurity-rich and low-impurity ice can have important consequences for ice dynamics close to the bedrock. © 2020 Author(s).
英文关键词	cryosphere; deformation; grain size; high temperature; ice core; ice flow; model validation; snowmelt; Arctic; Greenland
语种	英语
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202131
作者单位	Faculty of Earth Science, Utrecht University, TA Utrecht, 3508, Netherlands; Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, 27570, Germany; Department of Geosciences, Eberhard Karls University Tübingen, Tübingen, 72074, Germany
推荐引用方式 GB/T 7714	Kuiper E.-J.N.,De Bresser J.H.P.,Drury M.R.,et al. Using a composite flow law to model deformation in the NEEM deep ice core, Greenland-Part 2: The role of grain size and premelting on ice deformation at high homologous temperature[J],2020,14(7).
APA	Kuiper E.-J.N.,De Bresser J.H.P.,Drury M.R.,Eichler J.,Pennock G.M.,&Weikusat I..(2020).Using a composite flow law to model deformation in the NEEM deep ice core, Greenland-Part 2: The role of grain size and premelting on ice deformation at high homologous temperature.Cryosphere,14(7).
MLA	Kuiper E.-J.N.,et al."Using a composite flow law to model deformation in the NEEM deep ice core, Greenland-Part 2: The role of grain size and premelting on ice deformation at high homologous temperature".Cryosphere 14.7(2020).