气候变化领域集成服务门户(CCPortal): Dark ice dynamics of the south-west Greenland Ice Sheet

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DOI	10.5194/tc-11-2491-2017
	Dark ice dynamics of the south-west Greenland Ice Sheet
	Tedstone A.J.; Bamber J.L.; Cook J.M.; Williamson C.J.; Fettweis X.; Hodson A.J.; Tranter M.
发表日期	2017
ISSN	19940416
卷号	11 期号:6
英文摘要	Runoff from the Greenland Ice Sheet (GrIS) has increased in recent years due largely to changes in atmospheric circulation and atmospheric warming. Albedo reductions resulting from these changes have amplified surface melting. Some of the largest declines in GrIS albedo have occurred in the ablation zone of the south-west sector and are associated with the development of "dark" ice surfaces. Field observations at local scales reveal that a variety of light-absorbing impurities (LAIs) can be present on the surface, ranging from inorganic particulates to cryoconite materials and ice algae. Meanwhile, satellite observations show that the areal extent of dark ice has varied significantly between recent successive melt seasons. However, the processes that drive such large interannual variability in dark ice extent remain essentially unconstrained. At present we are therefore unable to project how the albedo of bare ice sectors of the GrIS will evolve in the future, causing uncertainty in the projected sea level contribution from the GrIS over the coming decades. Here we use MODIS satellite imagery to examine dark ice dynamics on the south-west GrIS each year from 2000 to 2016. We quantify dark ice in terms of its annual extent, duration, intensity and timing of first appearance. Not only does dark ice extent vary significantly between years but so too does its duration (from 0 to > 80 % of June-July-August, JJA), intensity and the timing of its first appearance. Comparison of dark ice dynamics with potential meteorological drivers from the regional climate model MAR reveals that the JJA sensible heat flux, the number of positive minimum-air-temperature days and the timing of bare ice appearance are significant interannual synoptic controls. We use these findings to identify the surface processes which are most likely to explain recent dark ice dynamics. We suggest that whilst the spatial distribution of dark ice is best explained by outcropping of particulates from ablating ice, these particulates alone do not drive dark ice dynamics. Instead, they may enable the growth of pigmented ice algal assemblages which cause visible surface darkening, but only when the climatological prerequisites of liquid meltwater presence and sufficient photosynthetically active radiation fluxes are met. Further field studies are required to fully constrain the processes by which ice algae growth proceeds and the apparent dependency of algae growth on melt-out particulates. © Author(s) 2017.
学科领域	ablation; annual variation; atmospheric circulation; climate modeling; melting; meltwater; MODIS; photosynthetically active radiation; regional climate; runoff; satellite imagery; spatial distribution; Arctic; Greenland; Greenland Ice Sheet; algae
语种	英语
scopus关键词	ablation; annual variation; atmospheric circulation; climate modeling; melting; meltwater; MODIS; photosynthetically active radiation; regional climate; runoff; satellite imagery; spatial distribution; Arctic; Greenland; Greenland Ice Sheet; algae
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/119317
作者单位	Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, Bristol, United Kingdom; Department of Geography, University of Sheffield, Winter Street, Sheffield, United Kingdom; Laboratory of Climatology, Department of Geography, University of Liège, Liège, Belgium; Arctic Geology, University Centre in Svalbard, Longyearbyen, Norway
推荐引用方式 GB/T 7714	Tedstone A.J.,Bamber J.L.,Cook J.M.,et al. Dark ice dynamics of the south-west Greenland Ice Sheet[J],2017,11(6).
APA	Tedstone A.J..,Bamber J.L..,Cook J.M..,Williamson C.J..,Fettweis X..,...&Tranter M..(2017).Dark ice dynamics of the south-west Greenland Ice Sheet.Cryosphere,11(6).
MLA	Tedstone A.J.,et al."Dark ice dynamics of the south-west Greenland Ice Sheet".Cryosphere 11.6(2017).