The influence of fracture-induced calving on Antarctica's contribution to future sea-level change

南极冰盖通过周围的冰架和止水冰川被排干了大约90%。冰山崩解是冰损失的主要机制，并以断裂为先决条件。通常，裂缝是在上游加速冰流中形成的，沿着冰架的剪切边缘形成，并随着冰带一起向冰裂锋移动。我们已经开发了一种模型方法来解释冰架裂缝的形成、生长和运输，并将结果与可见的卫星观测结果进行了比较。我们进一步介绍了冰流和断裂过程的宏观耦合，这代表了一种潜在的自放大反馈机制，并为冰流的几个观测特征提供了解释。在前人工作的基础上，我们希望扩展裂缝密度方法，并推导出裂缝耦合崩解参数化。通过使用由Christine Wesche （AWI）提供的实地数据和空中观测的新见解，我们希望量化冰山释放的预期平均大小和频率。在分离成冰山之前，我们将明确地考虑裂缝的垂直增长和裂缝的水平扩展。我们将在末次盛冰期（LGM）以来的南极冰盖模拟中应用这种增强的产犊参数化。在与迈克尔·韦伯和鲁珀特·格拉德斯通的合作下，我们想研究模拟冰山随海岸洋流的移动，将计算出的冰山通量与古沉积物数据进行比较。这一模式练习将全面了解过去的快速变化和未来气候变化中可能出现的动态反应。

The Antarctic ice sheet is drained to about 90% through the surrounding ice shelves and water-terminating glaciers. Iceberg calving is a major mechanism of ice loss and is preconditioned by fractures. Usually fractures form far upstream in accelerating ice streams and along the shear margins of the ice shelves and are transported in bands with the ice towards the calving front. We have already developed a model approach that accounts for the formation, growth and transport of fractures in ice shelves and compared the results to visible satellite observation. We further introduced a macroscopic coupling of ice flow and fracture processes, which represents a potentially self-amplifying feedback mechanism and provides explanations for several observed features of ice flow.Based on the previous work we want to expand the fracture-density approach and derive a fracture-coupled calving parameterization. By using new insights from field data and airborne observations, provided by Christine Wesche (AWI), we would like to quantify expected average size and frequency of iceberg release. We will account explicitly for the vertical growth of cracks and horizontal propagation of rifts before getting detached as icebergs. We will apply this enhanced calving parameterization in a simulation of the Antarctic ice sheet for the period since the Last Glacial Maximum (LGM). In collaboration with Michael Weber and Rupert Gladstone we would like to study the transport of simulated icebergs with the coastal current to compare the computed iceberg fluxes with paleo sediment data. This model exercise would provide a holistic understanding of fast changes in the past and possible dynamic responses in a changing future climate.