利用地表速度和海拔观测数据验证乌珀纳维-伊斯特拉姆的历史模拟集合(1985-2019 年

IF 2.8 3区 地球科学 Q2 GEOGRAPHY, PHYSICAL
Eliot Jager, Fabien Gillet-Chaulet, Jérémie Mouginot, Romain Millan
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引用次数: 0

摘要

未来潮水冰川对气候变暖的反应是格陵兰冰盖对全球海平面上升影响的最大不确定因素之一。在本研究中,我们研究了冰盖模型通过规定前沿位置来再现潮汐冰川乌珀纳维-伊斯特拉姆的速度和表面高程的过去演变的能力。为此,我们使用韦尔特曼摩擦定律和正则库仑摩擦定律进行了两组模拟。我们发现,冰流模型必须包括快速流动区域冰锋上游前 15 公里处摩擦力的减小,才能捕捉到 1985-2019 年期间观测到的趋势。如果没有这个过程,集合模型就会高估 2005 年冰锋后退前的冰流,并且不能完全再现后退过程中的冰流加速。这导致 1985 至 2019 年间的总质量损失被高估了 50%(3 亿吨对 2 亿吨)。通过基于方差的敏感性分析,我们发现摩擦定律和冰流定律的不确定性对模型结果的影响大于地表质量平衡和初始地表高程。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Validating ensemble historical simulations of Upernavik Isstrøm (1985–2019) using observations of surface velocity and elevation

The future of tidewater glaciers in response to climate warming is one of the largest sources of uncertainty in the contribution of the Greenland ice sheet to global sea-level rise. In this study, we investigate the ability of an ice-sheet model to reproduce the past evolution of the velocity and surface elevation of a tidewater glacier, Upernavik Isstrøm, by prescribing front positions. To achieve this, we run two ensembles of simulations with a Weertman and a regularised-Coulomb friction law. We show that the ice-flow model has to include a reduction in friction in the first 15 km upstream of the ice front in fast-flowing regions to capture the trends observed during the 1985–2019 period. Without this process, the ensemble model overestimates the ice flow before the retreat of the front in 2005 and does not fully reproduce its acceleration during the retreat. This results in an overestimation of the total mass loss between 1985 and 2019 of 50% (300 vs 200 Gt). Using a variance-based sensitivity analysis, we show that uncertainties in the friction law and the ice-flow law have a greater impact on the model results than surface mass balance and initial surface elevation.

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来源期刊
Journal of Glaciology
Journal of Glaciology 地学-地球科学综合
CiteScore
5.80
自引率
14.70%
发文量
101
审稿时长
6 months
期刊介绍: Journal of Glaciology publishes original scientific articles and letters in any aspect of glaciology- the study of ice. Studies of natural, artificial, and extraterrestrial ice and snow, as well as interactions between ice, snow and the atmospheric, oceanic and subglacial environment are all eligible. They may be based on field work, remote sensing, laboratory investigations, theoretical analysis or numerical modelling, or may report on newly developed glaciological instruments. Subjects covered recently in the Journal have included palaeoclimatology and the chemistry of the atmosphere as revealed in ice cores; theoretical and applied physics and chemistry of ice; the dynamics of glaciers and ice sheets, and changes in their extent and mass under climatic forcing; glacier energy balances at all scales; glacial landforms, and glaciers as geomorphic agents; snow science in all its aspects; ice as a host for surface and subglacial ecosystems; sea ice, icebergs and lake ice; and avalanche dynamics and other glacial hazards to human activity. Studies of permafrost and of ice in the Earth’s atmosphere are also within the domain of the Journal, as are interdisciplinary applications to engineering, biological, and social sciences, and studies in the history of glaciology.
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