气候变化领域集成服务门户(CCPortal): Development of physically based liquid water schemes for Greenland firn-densification models

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DOI	10.5194/tc-13-1819-2019
	Development of physically based liquid water schemes for Greenland firn-densification models
	Verjans V.; Leeson A.A.; Max Stevens C.; MacFerrin M.; Noël B.; Van Den Broeke M.R.
发表日期	2019
ISSN	19940416
EISSN	13
起始页码	1819
结束页码	1842
卷号	13 期号:7
英文摘要	As surface melt is increasing on the Greenland Ice Sheet (GrIS), quantifying the retention capacity of the firn layer is critical to linking meltwater production to meltwater runoff. Firn-densification models have so far relied on empirical approaches to account for the percolation-refreezing process, and more physically based representations of liquid water flow might bring improvements to model performance. Here we implement three types of water percolation schemes into the Community Firn Model: the bucket approach, the Richards equation in a single domain and the Richards equation in a dual domain, which accounts for partitioning between matrix and fast preferential flow. We investigate their impact on firn densification at four locations on the GrIS and compare model results with observations. We find that for all of the flow schemes, significant discrepancies remain with respect to observed firn density, particularly the density variability in depth, and that inter-model differences are large (porosity of the upper 15m firn varies by up to 47%). The simple bucket scheme is as efficient in replicating observed density profiles as the single-domain Richards equation, and the most physically detailed dual-domain scheme does not necessarily reach best agreement with observed data. However, we find that the implementation of preferential flow simulates ice-layer formation more reliably and allows for deeper percolation. We also find that the firn model is more sensitive to the choice of densification scheme than to the choice of water percolation scheme. The disagreements with observations and the spread in model results demonstrate that progress towards an accurate description of water flow in firn is necessary. The numerous uncertainties about firn structure (e.g. grain size and shape, presence of ice layers) and about its hydraulic properties, as well as the one-dimensionality of firn models, render the implementation of physically based percolation schemes difficult. Additionally, the performance of firn models is still affected by the various effects affecting the densification process such as microstructural effects, wet snow metamorphism and temperature sensitivity when meltwater is present. © 2019 Copernicus GmbH. All rights reserved.
学科领域	hydraulic property; meltwater; model; percolation; preferential flow; Richards equation; runoff; simulation; snow cover; water flow; Arctic; Greenland; Greenland Ice Sheet
语种	英语
scopus关键词	hydraulic property; meltwater; model; percolation; preferential flow; Richards equation; runoff; simulation; snow cover; water flow; Arctic; Greenland; Greenland Ice Sheet
来源期刊	The Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/118864
作者单位	Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YW, United Kingdom; Lancaster Environment Centre, Data Science Institute, Lancaster University, Lancaster, LA1 4YW, United Kingdom; Department of Earth and Space Sciences, University of Washington, Seattle, WA, United States; Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, United States; Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, Netherlands
推荐引用方式 GB/T 7714	Verjans V.,Leeson A.A.,Max Stevens C.,et al. Development of physically based liquid water schemes for Greenland firn-densification models[J],2019,13(7).
APA	Verjans V.,Leeson A.A.,Max Stevens C.,MacFerrin M.,Noël B.,&Van Den Broeke M.R..(2019).Development of physically based liquid water schemes for Greenland firn-densification models.The Cryosphere,13(7).
MLA	Verjans V.,et al."Development of physically based liquid water schemes for Greenland firn-densification models".The Cryosphere 13.7(2019).