Effects of ice mélange on ice flow and calving of Greenland glaciers in a warmer climate

海平面上升是全世界许多沿海社区的主要关切。预计格陵兰冰盖将在本世纪及以后大大加剧海平面上升。格陵兰岛大约一半的贡献来自于冰解出口冰川。冰山崩解主要是在冬季冰前海冰混合物厚而坚硬时受到抑制，并在春季混合物破裂后开始。因此，混杂是格陵兰岛对海平面上升的一个重要因素。然而，到目前为止，只有一个冰盖模型能够明确地模拟混合。为了使模型结果具有可比性，必须有更多的冰盖模型也能模拟混合。由我们小组使用和共同开发的平行冰盖模型（PISM）是一个成熟的冰盖模型，在世界范围内拥有大量用户。在气候变暖的情况下，我们预计会有更多的冰山崩解来喂养冰前混杂岩。与此同时，更高的温度也导致混合物的融化增加。我们想调查这两个相反的过程是否会导致混合物的总体增加，这将有助于稳定冰川，或者导致混合物的减少，这将进一步破坏已经退缩的冰川。在我们提出的研究项目中，我们计划在我们的冰盖模型PISM中实现混合模型，并分析混合在气候变暖时格陵兰冰川冰损失中的作用。 我们打算进行三个工作包：首先，我们计划在PISM中实现一个混杂模型组件，以冰盖模型中现有的混杂模型为例。其次，我们打算约束的参数和测试模型在两个不同的理想化设置，一个矩形通道和一个合成的海洋冰盖。最后，我们计划将我们的新混合模型应用于Jakobshavn Isbrae的区域模拟，Jakobshavn Isbrae是格陵兰冰盖西海岸最大的出口冰川之一。我们打算首先执行一个历史的自旋与贝叶斯方法使用合奏研究，然后进行未来的模拟，为这个世纪。

Sea level rise is a major concern for many coastal communities worldwide. The Greenland Ice Sheet is expected to contribute significantly to sea level rise this century and beyond. About half of Greenland's contribution comes from calving outlet glaciers. Iceberg calving is mainly suppressed in winter when the proglacial sea ice mélange is thick and stiff, and begins in spring after the mélange breaks up. Therefore, mélange is an important factor in Greenland's contribution to sea level rise. Until now, however, only one ice sheet model is capable of explicitly modeling mélange. In the interest of comparability of model results, it is important that more ice sheet models can also model mélange. The Parallel Ice Sheet Model (PISM), used and co-developed by our group, is a well-established ice sheet model with a large user base worldwide. In a warming climate, we expect increased iceberg calving to feed proglacial mélange. At the same time, higher temperatures also lead to increased melting of the mélange. We want to investigate whether these two opposing processes lead to an overall increase in mélange, which would help stabilize glaciers, or to a decrease in mélange, which would further destabilize already retreating glaciers. In our proposed research project, we plan to implement a mélange model in our ice sheet model PISM and analyze the role of mélange for the ice loss from a Greenland glacier in a warmer climate. We intend to pursue three work packages: First, we plan to implement a mélange model component in PISM, following the example of the existing mélange model within an ice sheet model. Second, we intend to constrain the parameters and test the model in two different idealized settings, a rectangular channel and a synthetic marine ice sheet. Finally, we plan to apply our new mélange model to a regional simulation of Jakobshavn Isbrae, one of the largest outlet glaciers on the west coast of the Greenland Ice Sheet. We intend to first perform a historical spinup using an ensemble study with a Bayesian approach, and then perform future simulations for this century.