气候变化领域集成服务门户(CCPortal): Algal growth and weathering crust state drive variability in western Greenland Ice Sheet ice albedo

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DOI	10.5194/tc-14-521-2020
	Algal growth and weathering crust state drive variability in western Greenland Ice Sheet ice albedo
	Tedstone A.J.; Cook J.M.; Williamson C.J.; Hofer S.; McCutcheon J.; Irvine-Fynn T.; Gribbin T.; Tranter M.
发表日期	2020
ISSN	19940416
起始页码	521
结束页码	538
卷号	14 期号:2
英文摘要	One of the primary controls upon the melting of the Greenland Ice Sheet (GrIS) is albedo, a measure of how much solar radiation that hits a surface is reflected without being absorbed. Lower-albedo snow and ice surfaces therefore warm more quickly. There is a major difference in the albedo of snow-covered versus bare-ice surfaces, but observations also show that there is substantial spatio-temporal variability of up to ~ 0.4 in bare-ice albedo. Variability in bare-ice albedo has been attributed to a number of processes including the accumulation of light-absorbing impurities (LAIs) and the changing physical properties of the nearsurface ice. However, the combined impact of these processes upon albedo remains poorly constrained. Here we use field observations to show that pigmented glacier algae are ubiquitous and cause surface darkening both within and outside the south-west GrIS "dark zone" but that other factors including modification of the ice surface by algal bloom presence, surface topography and weathering crust state are also important in determining patterns of daily albedo variability. We further use observations from an unmanned aerial system (UAS) to examine the scale gap in albedo between ground versus remotely sensed measurements made by Sentinel-2 (S-2) and MODIS. S-2 observations provide a highly conservative estimate of algal bloom presence because algal blooms occur in patches much smaller than the ground resolution of S-2 data. Nevertheless, the bare-ice albedo distribution at the scale of 20m×20m S-2 pixels is generally unimodal and unskewed. Conversely, bare-ice surfaces have a left-skewed albedo distribution at MODIS MOD10A1 scales. Thus, when MOD10A1 observations are used as input to energy balance modelling, meltwater production can be underestimated by ~ 2 %. Our study highlights that (1) the impact of the weathering crust state is of similar importance to the direct darkening role of light-absorbing impurities upon ice albedo and (2) there is a spatial-scale dependency in albedo measurement which reduces detection of real changes at coarser resolutions. © 2020 E. Schweizerbart'sche Verlagsbuchhandlung. All rights reserved.
英文关键词	albedo; algal bloom; energy balance; meltwater; MODIS; remotely operated vehicle; sea surface topography; solar radiation; weathering; Arctic; Greenland; Greenland Ice Sheet; algae
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/202222
作者单位	Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, Bristol, United Kingdom; Department of Geosciences, University of Fribourg, Fribourg, Switzerland; Department of Geography, University of Sheffield, Sheffield, United Kingdom; Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, United Kingdom; School of Earth and Environment, University of Leeds, Leeds, United Kingdom; Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, United Kingdom
推荐引用方式 GB/T 7714	Tedstone A.J.,Cook J.M.,Williamson C.J.,et al. Algal growth and weathering crust state drive variability in western Greenland Ice Sheet ice albedo[J],2020,14(2).
APA	Tedstone A.J..,Cook J.M..,Williamson C.J..,Hofer S..,McCutcheon J..,...&Tranter M..(2020).Algal growth and weathering crust state drive variability in western Greenland Ice Sheet ice albedo.Cryosphere,14(2).
MLA	Tedstone A.J.,et al."Algal growth and weathering crust state drive variability in western Greenland Ice Sheet ice albedo".Cryosphere 14.2(2020).