气候变化领域集成服务门户(CCPortal): Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events in Svalbard

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DOI	10.5194/tc-14-4217-2020
	Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events in Svalbard
	Alexander A.; Obu J.; Schuler T.V.; Kaä¨b A.; Christiansen H.H.
发表日期	2020
ISSN	19940416
起始页码	4217
结束页码	4231
卷号	14 期号:11
英文摘要	Cold glacier beds, i.e., where the ice is frozen to its base, are widespread in polar regions. Common theories state that stable permafrost should exist under glacier beds on shorter timescales, varying from years to decades. Presently, only a few direct measurements of both subglacial permafrost and the processes influencing its thermal regime exist. Here, we present subglacial permafrost and active layer measurements obtained from within the basal drainage systems of two cold-based glaciers on Svalbard during the summer melt season. Temperature observations were obtained from subglacial sediment that was accessed through the drainage systems of the two glaciers in the previous winters. The temperature records cover the periods from spring to autumn in 2016 and 2019 at the glaciers Larsbreen and Tellbreen in central Svalbard. The ground temperature below Larsbreen indicates colder ground conditions, whereas the temperatures of the Tellbreen drainage system show considerably warmer conditions, close to the freezing point. We suggest the latter is due to the presence of liquid water all year round inside the Tellbreen drainage system. Both drainage systems investigated show an increase in subglacial sediment temperatures after the disappearance of snow bridges and the subsequent connection to surface meltwater supply at the start of the summer melt season. Temperature records show influence of sudden summer water supply events, when heavy melt and rain left their signatures on the thermal regime and the erosion of the glacier bed. Observed vertical erosion can reach up to 0.9m d-1 at the base of basal drainage channels during summer. We also show that the thermal regime under the subglacial drainage systems is not stable during summer but experiences several freeze-thaw cycles driven by weather events. Our results show the direct importance of heavy melt events and rain on the thermal regime of subglacial permafrost and the erosion of the glacier bed in the vicinity of subglacial drainage channels. Increased precipitation and surface melt, as expected for future climate, will therefore likely lead to increased degradation of subglacial permafrost, as well as higher subglacial erosion of available sediment around the preferential hydrological paths. This in turn might have significant impacts on proglacial and fjord ecosystems due to increased sediment and nutrient input. © 2020 Author(s).
英文关键词	freeze-thaw cycle; glacial erosion; ice flow; periglacial environment; permafrost; seasonality; snowmelt; subglacial environment; temperature effect; Arctic; Svalbard; Svalbard and Jan Mayen
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/202014
作者单位	Department of Geosciences, University of Oslo, Oslo, 0316, Norway; Department of Arctic Geology, University Centre in Svalbard, Longyearbyen, 9171, Norway
推荐引用方式 GB/T 7714	Alexander A.,Obu J.,Schuler T.V.,et al. Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events in Svalbard[J],2020,14(11).
APA	Alexander A.,Obu J.,Schuler T.V.,Kaä¨b A.,&Christiansen H.H..(2020).Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events in Svalbard.Cryosphere,14(11).
MLA	Alexander A.,et al."Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events in Svalbard".Cryosphere 14.11(2020).