气候变化领域集成服务门户(CCPortal): Surface-layer turbulence, energy balance and links to atmospheric circulations over a mountain glacier in the French Alps

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DOI	10.5194/tc-11-971-2017
	Surface-layer turbulence, energy balance and links to atmospheric circulations over a mountain glacier in the French Alps
	Litt M.; Sicart J.E.; Six D.; Wagnon P.; Helgason W.D.
发表日期	2017
ISSN	19940416
卷号	11 期号:2
英文摘要	Over Saint-Sorlin Glacier in the French Alps (45° N, 6.1° E; ∼3 km2) in summer, we study the atmospheric surface-layer dynamics, turbulent fluxes, their uncertainties and their impact on surface energy balance (SEB) melt estimates. Results are classified with regard to large-scale forcing. We use high-frequency eddy-covariance data and mean air-temperature and wind-speed vertical profiles, collected in 2006 and 2009 in the glacier's atmospheric surface layer. We evaluate the turbulent fluxes with the eddy-covariance (sonic) and the profile method, and random errors and parametric uncertainties are evaluated by including different stability corrections and assuming different values for surface roughness lengths. For weak synoptic forcing, local thermal effects dominate the wind circulation. On the glacier, weak katabatic flows with a wind-speed maximum at low height (2-3m) are detected 71% of the time and are generally associated with small turbulent kinetic energy (TKE) and small net turbulent fluxes. Radiative fluxes dominate the SEB. When the large-scale forcing is strong, the wind in the valley aligns with the glacier flow, intense downslope flows are observed, no wind-speed maximum is visible below 5m, and TKE and net turbulent fluxes are often intense. The net turbulent fluxes contribute significantly to the SEB. The surface-layer turbulence production is probably not at equilibrium with dissipation because of interactions of large-scale orographic disturbances with the flow when the forcing is strong or low-frequency oscillations of the katabatic flow when the forcing is weak. In weak forcing when TKE is low, all turbulent fluxes calculation methods provide similar fluxes. In strong forcing when TKE is large, the choice of roughness lengths impacts strongly the net turbulent fluxes from the profile method fluxes and their uncertainties. However, the uncertainty on the total SEB remains too high with regard to the net observed melt to be able to recommend one turbulent flux calculation method over another. © Author(s) 2017.
学科领域	air temperature; atmospheric circulation; eddy covariance; energy balance; flux measurement; katabatic flow; kinetic energy; mountain region; surface layer; surface roughness; synoptic meteorology; turbulence; Alps; France; Rhone-Alpes; Saint Sorlin Glacier
语种	英语
scopus关键词	air temperature; atmospheric circulation; eddy covariance; energy balance; flux measurement; katabatic flow; kinetic energy; mountain region; surface layer; surface roughness; synoptic meteorology; turbulence; Alps; France; Rhone-Alpes; Saint Sorlin Glacier
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/119412
作者单位	Université Grenoble Alpes, CNRS, IRD, Grenoble INP, IGE, Grenoble, 38000, France; ICIMOD, GPO Box 3226, Kathmandu, Nepal; Civil and Geological Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada
推荐引用方式 GB/T 7714	Litt M.,Sicart J.E.,Six D.,et al. Surface-layer turbulence, energy balance and links to atmospheric circulations over a mountain glacier in the French Alps[J],2017,11(2).
APA	Litt M.,Sicart J.E.,Six D.,Wagnon P.,&Helgason W.D..(2017).Surface-layer turbulence, energy balance and links to atmospheric circulations over a mountain glacier in the French Alps.Cryosphere,11(2).
MLA	Litt M.,et al."Surface-layer turbulence, energy balance and links to atmospheric circulations over a mountain glacier in the French Alps".Cryosphere 11.2(2017).