气候变化领域集成服务门户(CCPortal): Extraordinary runoff from the Greenland ice sheet in 2012 amplified by hypsometry and depleted firn retention

CCPortal

DOI	10.5194/tc-10-1147-2016
	Extraordinary runoff from the Greenland ice sheet in 2012 amplified by hypsometry and depleted firn retention
	Mikkelsen A.B.; Hubbard A.; Macferrin M.; Eric Box J.; Doyle S.H.; Fitzpatrick A.; Hasholt B.; Bailey H.L.; Lindbäck K.; Pettersson R.
发表日期	2016
ISSN	19940416
卷号	10 期号:3
英文摘要	It has been argued that the infiltration and retention of meltwater within firn across the percolation zone of the Greenland ice sheet has the potential to buffer up to ĝc;1/4 3.6mm of global sea-level rise (Harper et al., 2012). Despite evidence confirming active refreezing processes above the equilibrium line, their impact on runoff and proglacial discharge has yet to be assessed. Here, we compare meteorological, melt, firn stratigraphy and discharge data from the extreme 2010 and 2012 summers to determine the relationship between atmospheric forcing and melt runoff at the land-terminating Kangerlussuaq sector of the Greenland ice sheet, which drains into the Watson River. The 6.8km3 bulk discharge in 2012 exceeded that in 2010 by 28%, despite only a 3% difference in net incoming melt energy between the two years. This large disparity can be explained by a 10% contribution of runoff originating from above the long-term equilibrium line in 2012 caused by diminished firn retention. The amplified 2012 response was compounded by catchment hypsometry; the disproportionate increase in area contributing to runoff as the melt-level rose high into the accumulation area. Satellite imagery and aerial photographs reveal an extensive supraglacial network extending 140km from the ice margin that confirms active meltwater runoff originating well above the equilibrium line. This runoff culminated in three days with record discharge of 3100m3s-1 (0.27Gtd-1) that peaked on 11 July and washed out the Watson River Bridge. Our findings corroborate melt infiltration processes in the percolation zone, though the resulting patterns of refreezing are complex and can lead to spatially extensive, perched superimposed ice layers within the firn. In 2012, such layers extended to an elevation of at least 1840m and provided a semi-impermeable barrier to further meltwater storage, thereby promoting widespread runoff from the accumulation area of the Greenland ice sheet that contributed directly to proglacial discharge and global sea-level rise. © Author(s) 2016.
学科领域	atmospheric forcing; firn; hypsometry; ice margin; infiltration; meltwater; percolation; proglacial environment; river discharge; runoff; sea level change; spatiotemporal analysis; water retention; Arctic; Greenland; Greenland Ice Sheet; Kangerlussuaq Fjord; Watson River
语种	英语
scopus关键词	atmospheric forcing; firn; hypsometry; ice margin; infiltration; meltwater; percolation; proglacial environment; river discharge; runoff; sea level change; spatiotemporal analysis; water retention; Arctic; Greenland; Greenland Ice Sheet; Kangerlussuaq Fjord; Watson River
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/119640
作者单位	Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark; Centre for Permafrost (CENPERM), University of Copenhagen, Øster Voldgade 10, Copenhagen, 1350, Denmark; Centre for Arctic Gas Hydrate, Environment and Climate, Department of Geology, University of Tromsø, Dramsveien 201, Tromsø, 9037, Norway; Centre for Glaciology, Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, SY23 3DB, United Kingdom; Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO, United States; Department of Glaciology and Climate, Geological Survey of Denmark and Greenland, Copenhagen, Denmark; Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, Periglacial Research Section, Potsdam, 14473, Germany; Department of Earth Sciences, Uppsala Universitet, Villav. 16, Uppsala, 752 36, Sweden
推荐引用方式 GB/T 7714	Mikkelsen A.B.,Hubbard A.,Macferrin M.,et al. Extraordinary runoff from the Greenland ice sheet in 2012 amplified by hypsometry and depleted firn retention[J],2016,10(3).
APA	Mikkelsen A.B..,Hubbard A..,Macferrin M..,Eric Box J..,Doyle S.H..,...&Pettersson R..(2016).Extraordinary runoff from the Greenland ice sheet in 2012 amplified by hypsometry and depleted firn retention.Cryosphere,10(3).
MLA	Mikkelsen A.B.,et al."Extraordinary runoff from the Greenland ice sheet in 2012 amplified by hypsometry and depleted firn retention".Cryosphere 10.3(2016).