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DOI | 10.5194/tc-13-2475-2019 |
A simple stress-based cliff-calving law | |
Schlemm T.; Levermann A. | |
发表日期 | 2019 |
ISSN | 19940416 |
EISSN | 13 |
起始页码 | 2475 |
结束页码 | 2488 |
卷号 | 13期号:9 |
英文摘要 | Over large coastal regions in Greenland and Antarctica the ice sheet calves directly into the ocean. In contrast to ice-shelf calving, an increase in calving from grounded glaciers contributes directly to sea-level rise. Ice cliffs with a glacier freeboard larger than ≈100 m are currently not observed, but it has been shown that such ice cliffs are increasingly unstable with increasing ice thickness. This cliff calving can constitute a self-amplifying ice loss mechanism that may significantly alter sea-level projections both of Greenland and Antarctica. Here we seek to derive a minimalist stress-based parametrization for cliff calving from grounded glaciers whose freeboards exceed the 100 m stability limit derived in previous studies. This will be an extension of existing calving laws for tidewater glaciers to higher ice cliffs. To this end we compute the stress field for a glacier with a simplified two-dimensional geometry from the two-dimensional Stokes equation. First we assume a constant yield stress to derive the failure region at the glacier front from the stress field within the glacier. Secondly, we assume a constant response time of ice failure due to exceedance of the yield stress. With this strongly constraining but very simple set of assumptions we propose a cliff-calving law where the calving rate follows a power-law dependence on the freeboard of the ice with exponents between 2 and 3, depending on the relative water depth at the calving front. The critical freeboard below which the ice front is stable decreases with increasing relative water depth of the calving front. For a dry water front it is, for example, 75 m. The purpose of this study is not to provide a comprehensive calving law but to derive a particularly simple equation with a transparent and minimalist set of assumptions. © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License. |
学科领域 | cliff; geometry; glacier dynamics; ice sheet; ice shelf; ice thickness; iceberg calving; sea level change; stress field; water depth; Antarctica; Arctic; Greenland |
语种 | 英语 |
scopus关键词 | cliff; geometry; glacier dynamics; ice sheet; ice shelf; ice thickness; iceberg calving; sea level change; stress field; water depth; Antarctica; Arctic; Greenland |
来源期刊 | The Cryosphere
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文献类型 | 期刊论文 |
条目标识符 | http://gcip.llas.ac.cn/handle/2XKMVOVA/118834 |
作者单位 | Potsdam Institute for Climate Impact Research, Potsdam, Germany; Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germany; Lamont-Doherty Earth Observatory, Columbia UniversityNY, United States |
推荐引用方式 GB/T 7714 | Schlemm T.,Levermann A.. A simple stress-based cliff-calving law[J],2019,13(9). |
APA | Schlemm T.,&Levermann A..(2019).A simple stress-based cliff-calving law.The Cryosphere,13(9). |
MLA | Schlemm T.,et al."A simple stress-based cliff-calving law".The Cryosphere 13.9(2019). |
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