气候变化领域集成服务门户(CCPortal): Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery

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DOI	10.5194/tc-15-1587-2021
	Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery
	Benedek C.L.; Willis I.C.
发表日期	2021
ISSN	19940416
起始页码	1587
结束页码	1606
卷号	15 期号:3
英文摘要	Surface lakes on the Greenland Ice Sheet play a key role in its surface mass balance, hydrology and biogeochemistry. They often drain rapidly in the summer via hydrofracture, which delivers lake water to the ice sheet base over timescales of hours to days and then can allow meltwater to reach the base for the rest of the summer. Rapid lake drainage, therefore, influences subglacial drainage evolution; water pressures; ice flow; biogeochemical activity; and ultimately the delivery of water, sediments and nutrients to the ocean. It has generally been assumed that rapid lake drainage events are confined to the summer, as this is typically when observations are made using satellite optical imagery. Here we develop a method to quantify backscatter changes in satellite radar imagery, which we use to document the drainage of six different lakes during three winters (2014/15, 2015/16 and 2016/17) in fast-flowing parts of the Greenland Ice Sheet. Analysis of optical imagery from before and after the three winters supports the radar-based evidence for winter lake drainage events and also provides estimates of lake drainage volumes, which range between 0.000046 ± 0.000017 and 0.0200 ± 0.002817 km3. For three of the events, optical imagery allows repeat photoclinometry (shape from shading) calculations to be made showing mean vertical collapse of the lake surfaces ranging between 1.21 ± 1.61 and 7.25 ± 1.61 m and drainage volumes of 0.002 ± 0.002968 to 0.044 ± 0.009858 km3. For one of these three, time-stamped ArcticDEM strips allow for DEM differencing, which demonstrates a mean collapse depth of 2.17 ± 0.28 m across the lake area. The findings show that lake drainage can occur in the winter in the absence of active surface melt and notable ice flow acceleration, which may have important implications for subglacial hydrology and biogeochemical processes. © Author(s) 2021.
英文关键词	backscatter; digital elevation model; ice sheet; lacustrine deposit; lacustrine environment; lake water; radar; satellite imagery; seasonal variation; Sentinel; winter; Arctic; Greenland; Greenland Ice Sheet
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/202277
作者单位	Scott Polar Research Institute, University of Cambridge, Cambridge, CB2 1ER, United Kingdom
推荐引用方式 GB/T 7714	Benedek C.L.,Willis I.C.. Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery[J],2021,15(3).
APA	Benedek C.L.,&Willis I.C..(2021).Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery.Cryosphere,15(3).
MLA	Benedek C.L.,et al."Winter drainage of surface lakes on the Greenland Ice Sheet from Sentinel-1 SAR imagery".Cryosphere 15.3(2021).