气候变化领域集成服务门户(CCPortal): Spatio-temporal flow variations driving heat exchange processes at a mountain glacier

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DOI	10.5194/tc-14-4699-2020
	Spatio-temporal flow variations driving heat exchange processes at a mountain glacier
	Mott R.; Stiperski I.; Nicholson L.
发表日期	2020
ISSN	19940416
起始页码	4699
结束页码	4718
卷号	14 期号:12
英文摘要	Multi-scale interactions between the glacier surface, the overlying atmosphere, and the surrounding alpine terrain are highly complex and force temporally and spatially variable local glacier energy fluxes and melt rates. A comprehensive measurement campaign (Hintereisferner Experiment, HEFEX) was conducted during August 2018 with the aim to investigate spatial and temporal dynamics of the near-surface boundary layer and associated heat exchange processes close to the glacier surface during the melting season. The experimental set-up of five meteorological stations was designed to capture the spatial and temporal characteristics of the local wind system on the glacier and to quantify the contribution of horizontal heat advection from surrounding ice-free areas to the local energy flux variability at the glacier. Turbulence data suggest that temporal changes in the local wind system strongly affect the micrometeorology at the glacier surface. Persistent low-level katabatic flows during both night and daytime cause consistently low near-surface air temperatures with only small spatial variability. However, strong changes in the local thermodynamic characteristics occur when westerly flows disturbed this prevailing katabatic flow, forming across-glacier flows and facilitating warm-air advection from the surrounding ice-free areas. Such heat advection significantly increased near-surface air temperatures at the glacier, resulting in strong horizontal temperature gradients from the peripheral zones towards the centre line of the glacier. Despite generally lower near-surface wind speeds during across-glacier flow, peak horizontal heat advection from the peripheral zones towards the centre line and strong transport of turbulence from higher atmospheric layers downward resulted in enhanced turbulent heat exchange towards the glacier surface at the glacier centre line. Thus, at the centre line of the glacier, exposure to strong larger-scale westerly winds promoted heat exchange processes, potentially contributing to ice melt, while at the peripheral zones of the glacier, stronger sheltering from larger-scale flows allowed the preservation of a katabatic jet, which suppressed the efficiency of the across-glacier flow to drive heat exchange towards the glacier surface by decoupling low-level atmospheric layers from the flow aloft. A fuller explanation of the origin and structure of the across-glacier flow would require large-eddy simulations. © Author(s) 2020.
英文关键词	glacier; heat flux; mountain region; spatiotemporal analysis
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/202162
作者单位	WSL Institute for Snow and Avalanche Research, SLF, Davos, Switzerland; Institute of Meteorology and Climate Research, Atmospheric Environmental Research (KIT/IMK-IFU), Garmisch-Partenkirchen, Germany; Department of Atmospheric and Cryospheric Sciences, University of Innsbruck, Innsbruck, Austria
推荐引用方式 GB/T 7714	Mott R.,Stiperski I.,Nicholson L.. Spatio-temporal flow variations driving heat exchange processes at a mountain glacier[J],2020,14(12).
APA	Mott R.,Stiperski I.,&Nicholson L..(2020).Spatio-temporal flow variations driving heat exchange processes at a mountain glacier.Cryosphere,14(12).
MLA	Mott R.,et al."Spatio-temporal flow variations driving heat exchange processes at a mountain glacier".Cryosphere 14.12(2020).