Ice shelf fracture parameterization in an ice sheet model
Ice shelf fracture parameterization in an ice sheet model
复制标题
冰盖模型中的冰架断裂参数化
DOI：
10.5194/tc-11-2543-2017
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发表时间：
2017
期刊：
影响因子：
5.2
通讯作者：
Zhao Liyun
中科院分区：
文献类型：
--
作者：
Sun Sainan;Cornford Stephen L;Moore John C;Gladstone Rupert;Zhao Liyun
漂浮的冰架对内陆冰盖施加了稳定力。然而，这种支撑作用被断裂过程所削弱，断裂过程在大规模上有效地软化了冰，加速了冰的流动，增加了冰解，并可能导致冰架破裂。我们添加了一个连续损伤模型（CDM）的BISICLES冰盖模型，这是为了模拟局部开口的裂缝应力下，这些裂缝通过冰盖的运输，裂缝深度和冰流场之间的耦合，并进行理想化的数值实验研究大规模冰盖和货架动态的广泛影响。在每一种情况下，我们都看到一种复杂的破坏模式随着时间的推移而演变，最终失去的支撑大约相当于冰架厚度的一半。我们发现，它是可能的，以实现类似的冰流模式，使用一个简单的经验法则：在模型域中的任何地方引入一个增强因子10。然而，空间变化的损害（或等效的，增强因子）字段设置在开始的预测计算，以匹配速度观测，广泛做冰盖模拟，应该演变的时间，或接地线撤退可以减缓一个数量级。
Floating ice shelves exert a stabilizing force onto the inland ice sheet. However, this buttressing effect is diminished by the fracture process, which on large scales effectively softens the ice, accelerating its flow, increasing calving, and potentially leading to ice shelf breakup. We add a continuum damage model (CDM) to the BISICLES ice sheet model, which is intended to model the localized opening of crevasses under stress, the transport of those crevasses through the ice sheet, and the coupling between crevasse depth and the ice flow field and to carry out idealized numerical experiments examining the broad impact on large-scale ice sheet and shelf dynamics. In each case we see a complex pattern of damage evolve over time, with an eventual loss of buttressing approximately equivalent to halving the thickness of the ice shelf. We find that it is possible to achieve a similar ice flow pattern using a simple rule of thumb: introducing an enhancement factor ∼ 10 everywhere in the model domain. However, spatially varying damage (or equivalently, enhancement factor) fields set at the start of prognostic calculations to match velocity observations, as is widely done in ice sheet simulations, ought to evolve in time, or grounding line retreat can be slowed by an order of magnitude.