气候变化领域集成服务门户(CCPortal): A new surface meltwater routing model for use on the Greenland Ice Sheet surface

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DOI	10.5194/tc-12-3791-2018
	A new surface meltwater routing model for use on the Greenland Ice Sheet surface
	Yang K.; Smith L.C.; Karlstrom L.; Cooper M.G.; Tedesco M.; Van As D.; Cheng X.; Chen Z.; Li M.
发表日期	2018
ISSN	19940416
卷号	12 期号:12
英文摘要	Large volumes of surface meltwater are routed through supraglacial internally drained catchments (IDCs) on the Greenland Ice Sheet surface each summer. Because surface routing impacts the timing and discharge of meltwater entering the ice sheet through moulins, accurately modeling moulin hydrographs is crucial for correctly coupling surface energy and mass balance models with subglacial hydrology and ice dynamics. Yet surface routing of meltwater on ice sheets remains a poorly understood physical process. We use high-resolution (0.5 m) satellite imagery and a derivative high-resolution (3.0 m) digital elevation model to partition the runoff-contributing area of the Rio Behar catchment, a moderately sized (∼ 63 km2) midelevation (1207-1381 m) IDC in the southwestern Greenland ablation zone, into open meltwater channels (supraglacial streams and rivers) and interfluves (small upland areas draining to surface channels, also called "hillslopes" in terrestrial geomorphology). A simultaneous in situ moulin discharge hydrograph was previously acquired for this catchment in July 2015. By combining the in situ discharge measurements with remote sensing and classic hydrological theory, we determine mean meltwater routing velocities through open channels and interfluves within the catchment. Two traditional terrestrial hydrology surface routing models, the unit hydrograph and rescaled width function, are applied and also compared with a surface routing and lake-filling model. We conclude that (1) surface meltwater is routed by slow interfluve flow (∼ 10-3-10-4 ms-1) and fast open-channel flow (∼ 10-1 ms-1); (2) the slow interfluve velocities are physically consistent with shallow, unsaturated subsurface porous media flow (∼ 10-4-10-5 ms-1) more than overland sheet flow (∼ 10-2 ms-1); (3) the open-channel velocities yield mean Manning's roughness coefficient (n) values of ∼ 0:03-0.05 averaged across the Rio Behar supraglacial stream-river network; (4) interfluve and open-channel flow travel distances have mean length scales of ∼ 100-101 m and ∼ 103 m, respectively; and (5) seasonal evolution of supraglacial drainage density will alter these length scales and the proportion of interfluves vs. open channels and thus the magnitude and timing of meltwater discharge received at the outlet moulin. This phenomenon may explain seasonal subglacial water pressure variations measured in a borehole ∼ 20 km away. In general, we conclude that in addition to fast open-channel transport through supraglacial streams and rivers, slow interfluve processes must also be considered in ice sheet surface meltwater routing models. Interfluves are characterized by slow overland and/or shallow subsurface flow, and it appears that shallow unsaturated porous-media flow occurs even in the bare-ice ablation zone. Together, both interfluves and open channels combine to modulate the timing and discharge of meltwater reaching IDC outlet moulins, prior to further modification by englacial and subglacial processes. © 2018 Author(s).
学科领域	catchment; digital elevation model; drainage basin; hydrological modeling; ice sheet; meltwater; overland flow; remote sensing; river discharge; runoff; satellite imagery; sheet flow; subglacial environment; subsurface flow; surface energy; Arctic; Greenland; Greenland Ice Sheet
语种	英语
scopus关键词	catchment; digital elevation model; drainage basin; hydrological modeling; ice sheet; meltwater; overland flow; remote sensing; river discharge; runoff; satellite imagery; sheet flow; subglacial environment; subsurface flow; surface energy; Arctic; Greenland; Greenland Ice Sheet
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/119020
作者单位	School of Geography and Ocean Science, Nanjing University, Nanjing, 210023, China; Joint Center for Global Change Studies, Beijing, 100875, China; Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, Nanjing, 210023, China; Department of Geography, University of California, Los Angeles, CA 90095, United States; Department of Earth Sciences, University of Oregon, Eugene, OR 97403, United States; Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, United States; Geological Survey of Denmark and Greenland, Øster Voldgade 10, Copenhagen, 1350, Denmark; State Key Laboratory of Remote Sensing Science, College of Global Change and Earth System Science, Beijing Normal University, Beijing, 100875, China
推荐引用方式 GB/T 7714	Yang K.,Smith L.C.,Karlstrom L.,et al. A new surface meltwater routing model for use on the Greenland Ice Sheet surface[J],2018,12(12).
APA	Yang K..,Smith L.C..,Karlstrom L..,Cooper M.G..,Tedesco M..,...&Li M..(2018).A new surface meltwater routing model for use on the Greenland Ice Sheet surface.Cryosphere,12(12).
MLA	Yang K.,et al."A new surface meltwater routing model for use on the Greenland Ice Sheet surface".Cryosphere 12.12(2018).