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

海平面上升是全球许多沿海社区关注的主要问题。预计格陵兰冰盖将对本世纪及以后的海平面上升作出重大贡献。格陵兰岛大约一半的贡献来自冰川的崩解。冰山崩解主要在原冰期海冰（msamuange）厚而硬的冬季受到抑制，在msamuange破裂后的春季开始。因此，在格陵兰岛对海平面上升的贡献中，msamuange是一个重要因素。然而，到目前为止，只有一种冰盖模型能够明确地模拟msamange。为了模型结果的可比性，重要的是要有更多的冰盖模型也能模拟大范围的冰。平行冰盖模型（PISM）是由我们小组使用和共同开发的，是一个完善的冰盖模型，在全球拥有大量的用户基础。在气候变暖的情况下，我们预计会有更多的冰山崩解，为前冰期的冰川提供营养。同时，较高的温度也会导致金属熔点的增加。我们想要调查这两个相反的过程是否会导致总体上的msamange增加，这将有助于稳定冰川，或者导致msamange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中实施一个msamuange模型，并分析msamuange在温暖气候下格陵兰冰川冰损失中的作用。我们打算追求三个工作包：首先，我们计划在PISM中实现一个msamuange模型组件，遵循冰原模型中现有的msamuange模型的示例。其次，我们打算约束参数并在两种不同的理想环境下测试模型，矩形通道和合成海洋冰盖。最后，我们计划将我们的新msamange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。我们打算首先使用贝叶斯方法的集合研究进行历史旋转，然后进行本世纪的未来模拟。

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.