Comparison of four calving laws to model Greenland outlet glaciers
Comparison of four calving laws to model Greenland outlet glaciers
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DOI：
10.5194/tc-12-3735-2018
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发表时间：
2018-11-29
期刊：
影响因子：
5.2
通讯作者：
Bondzio, Johannes H.
中科院分区：
文献类型：
--
作者：
Choi, Youngmin;Morlighem, Mathieu;Bondzio, Johannes H.
冰解作用是控制格陵兰海洋冰川动态的重要机制。冰山崩解在终点影响整个应力制度的出口冰川，这可能会导致进一步撤退和冰流加速。因此，必须在冰盖模型中准确地参数化冰解，以改进对未来几十年冰盖变化的预测，减少其对海平面上升影响的不确定性。已经提出了几个冰解定律，但其中大多数仅适用于特定区域，尚未在其他冰川上进行测试，而其他一些定律仅在一维流线或垂直流带模型中实施。在这里，我们使用冰盖系统模型（ISSM）测试并比较了文献中最近提出的几种产犊定律。我们测试这些冰解的法律对格陵兰岛的9个冰川。我们比较了模拟的冰锋演变，从过去10年收集的陆地卫星数据观察到的撤退，并评估哪个产犊法对每个冰川有更好的预测能力。总的来说，冯米塞斯张应力产犊法是更令人满意的比其他法律模拟观察到的冰前撤退，但新的参数化，更好地捕捉不同的模式产犊应开发。虽然冰锋的最终位置是不同的预测模拟与不同的产犊法，我们的研究结果证实，冰锋撤退高度依赖于床的地形，无论采用的产犊法。这项研究还证实，崩解动力学需要在冰盖模型的3-D或平面图，以解释复杂的河床地形和狭窄的峡湾沿着格陵兰岛海岸。
Calving is an important mechanism that controls the dynamics of marine terminating glaciers of Greenland. Iceberg calving at the terminus affects the entire stress regime of outlet glaciers, which may lead to further retreat and ice flow acceleration. It is therefore critical to accurately parameterize calving in ice sheet models in order to improve the projections of ice sheet change over the coming decades and reduce the uncertainty in their contribution to sea-level rise. Several calving laws have been proposed, but most of them have been applied only to a specific region and have not been tested on other glaciers, while some others have only been implemented in 1-D flowline or vertical flowband models. Here, we test and compare several calving laws recently proposed in the literature using the Ice Sheet System Model (ISSM). We test these calving laws on nine tidewater glaciers of Greenland. We compare the modeled ice front evolution to the observed retreat from Landsat data collected over the past 10 years, and assess which calving law has better predictive abilities for each glacier. Overall, the von Mises tensile stress calving law is more satisfactory than other laws for simulating observed ice front retreat, but new parameterizations that better capture the different modes of calving should be developed. Although the final positions of ice fronts are different for forecast simulations with different calving laws, our results confirm that ice front retreat highly depends on bed topography, irrespective of the calving law employed. This study also confirms that calving dynamics needs to be 3-D or in plan view in ice sheet models to account for complex bed topography and narrow fjords along the coast of Greenland.