气候变化领域集成服务门户(CCPortal): Mechanics and dynamics of pinning points on the Shirase Coast, West Antarctica

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DOI	10.5194/tc-15-2647-2021
	Mechanics and dynamics of pinning points on the Shirase Coast, West Antarctica
	Still H.; Hulbe C.
发表日期	2021
ISSN	19940416
起始页码	2647
结束页码	2665
卷号	15 期号:6
英文摘要	Ice rises and rumples, sites of localised ice-shelf grounding, modify ice-shelf flow by generating lateral and basal shear stresses, upstream compression, and downstream tension. Studies of pinning points typically quantify this role indirectly, through related metrics such as a buttressing number. Here, we quantify the dynamic effects of pinning points directly, by comparing model-simulated stress states in the Ross Ice Shelf (RIS) with and without a specific set of pinning points located downstream of the MacAyeal and Bindschadler ice streams (MacIS and BIS, respectively). Because ice properties are only known indirectly, the experiment is repeated with different realisations of the ice softness. While longitudinal stretching, and thus ice velocity, is smaller with the pinning points, flow resistance generated by other grounded features is also smaller. Conversely, flow resistance generated by other grounded features increases when the pinning points are absent, providing a non-local control on the net effect of the pinning points on ice-shelf flow. We find that an ice stream located directly upstream of the pinning points, MacIS, is less responsive to their removal than the obliquely oriented BIS. This response is due to zones of locally higher basal drag acting on MacIS, which may itself be a consequence of the coupled ice-shelf and ice-stream response to the pinning points. We also find that inversion of present-day flow and thickness for basal friction and ice softness, without feature-specific, a posteriori adjustment, leads to the incorrect representation of ice rumple morphology and an incorrect boundary condition at the ice base. Viewed from the perspective of change detection, we find that, following pinning point removal, the ice shelf undergoes an adjustment to a new steady state that involves an initial increase in ice speeds across the eastern ice shelf, followed by decaying flow speeds, as mass flux reduces thickness gradients in some areas and increases thickness gradients in others. Increases in ice-stream flow speeds persist with no further adjustment, even without sustained grounding-line retreat. Where pinning point effects are important, model tuning that respects their morphology is necessary to represent the system as a whole and inform interpretations of observed change. © 2021 Holly Still.
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/202433
作者单位	National School of Surveying, University of Otago, Dunedin, New Zealand
推荐引用方式 GB/T 7714	Still H.,Hulbe C.. Mechanics and dynamics of pinning points on the Shirase Coast, West Antarctica[J],2021,15(6).
APA	Still H.,&Hulbe C..(2021).Mechanics and dynamics of pinning points on the Shirase Coast, West Antarctica.Cryosphere,15(6).
MLA	Still H.,et al."Mechanics and dynamics of pinning points on the Shirase Coast, West Antarctica".Cryosphere 15.6(2021).