DOI: 10.5194/tc-14-17-2020
论文题名: Exploring mechanisms responsible for tidal modulation in flow of the Filchner-Ronne Ice Shelf
作者: Rosier S.H.R. ; Gudmundsson G.H.
刊名: Cryosphere
ISSN: 19940416
出版年: 2020
卷: 14, 期: 1 起始页码: 17
结束页码: 37
语种: 英语
英文关键词: flow modeling
; GPS
; ice flow
; ice shelf
; rheology
; slope dynamics
; tidal constituent
; tidewater glacier
; viscoelasticity
; Antarctica
; Filchner-Ronne Ice Shelf
; West Antarctica
英文摘要: An extensive network of GPS sites on the Filchner-Ronne Ice Shelf and adjoining ice streams shows strong tidal modulation of horizontal ice flow at a range of frequencies. A particularly strong (horizontal) response is found at the fortnightly (Msf) frequency. Since this tidal constituent is absent in the (vertical) tidal forcing, this observation implies the action of some non-linear mechanism. Another striking aspect is the strong amplitude of the flow perturbation, causing a periodic reversal in the direction of ice shelf flow in some areas and a 10 %-20% change in speed at grounding lines. No model has yet been able to reproduce the quantitative aspects of the observed tidal modulation across the entire Filchner-Ronne Ice Shelf. The cause of the tidal ice flow response has, therefore, remained an enigma, indicating a serious limitation in our current understanding of the mechanics of large-scale ice flow. A further limitation of previous studies is that they have all focused on isolated regions and interactions between different areas have, therefore, not been fully accounted for. Here, we conduct the first largescale ice flow modelling study to explore these processes using a viscoelastic rheology and realistic geometry of the entire Filchner-Ronne Ice Shelf, where the best observations of tidal response are available. We evaluate all relevant mechanisms that have hitherto been put forward to explain how tides might affect ice shelf flow and compare our results with observational data. We conclude that, while some are able to generate the correct general qualitative aspects of the tidally induced perturbations in ice flow, most of these mechanisms must be ruled out as being the primary cause of the observed long-period response. We find that only tidally induced lateral migration of grounding lines can generate a sufficiently strong long-period Msf response on the ice shelf to match observations. Furthermore, we show that the observed horizontal short-period semidiurnal tidal motion, causing twicedaily flow reversals at the ice front, can be generated through a purely elastic response to basin-wide tidal perturbations in the ice shelf slope. This model also allows us to quantify the effect of tides on mean ice flow and we find that the Filchner-Ronne Ice Shelf flows, on average, ∼21% faster than it would in the absence of large ocean tides. © Author(s) 2020. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/164573
Appears in Collections: 气候变化与战略
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作者单位: Department of Geography and Environmental Sciences, Northumbria University, Newcastle upon Tyne, NE1 8ST, United Kingdom
Recommended Citation:
Rosier S.H.R.,Gudmundsson G.H.. Exploring mechanisms responsible for tidal modulation in flow of the Filchner-Ronne Ice Shelf[J]. Cryosphere,2020-01-01,14(1)