Assessment of the ocean contribution to mass loss of Greenland’s peripheral glaciers – a scale-transitioning approach

评估海洋对格陵兰岛外围冰川质量损失的贡献——一种尺度转换方法

• 批准号: 443246981
• 负责人: Professor Dr. Ben Marzeion
• 金额: --
• 依托单位: Geographisches Institut
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/443246981?language=en
• 关键词: Assessment; ocean; contribution; mass; loss

Apart from the large main ice sheet, Greenland is home to a huge number of far smaller peripheral glaciers. Their contribution to the overall mass change of Greenland is greatly exceeding their share of ice mass, and surface area. Since they are mostly located in mountainous terrain along the coast of the island, numerical models of these ice masses need to consider the adequate spatial resolution, which cannot be achieved by ice sheet models. Tidewater glaciers are contributing a particularly large part to the overall mass loss. During 2003 to 2008, the peripheral glaciers contributed 14% to the overall ice mass loss of Greenland. Their contribution to sea level rise is projected to increase in the future, with currently available projections suggesting ice mass losses of the peripheral glaciers of up to 50% during the 21st century under RCP 8.5 forcing. There is strong spatial variation in peripheral glacier mass change, which mirrors a complex combination of forcing mechanisms from both atmosphere and ocean. Nevertheless, none of the currently available models which are capable of calculating regional-scale glacier mass change explicitly includes ocean forcing of frontal ablation processes at the marine-terminating fronts of tidewater glaciers. Except for two models, none even considers any frontal ablation processes at all. Hence, no past, present or future estimates of frontal ablation at Greenland's peripheral tidewater glaciers are available so far.The aim of the project is to produce projections of the future evolution of Greenland's peripheral glaciers during the 21st century, forced by the CMIP6 ensemble, with special attention to tidewater glaciers. We will quantify their freshwater discharge and contribution to sea-level rise. We will extend the Open Global Glacier Model (OGGM) to include ocean forcing in its frontal ablation module. This will be assisted by dedicated downscaling routines for both atmospheric and oceanic boundary conditions. We will evaluate the performance of OGGM with respect to the application of different scales of forcing data to determine if, and to which extent, optimized scale transitioning from the large synoptic scale down to the smaller local scale of the peripheral glaciers is able to increase model performance. The project results will provide an increased understanding of the influence ocean and atmosphere on the evolution of Greenland's peripheral glaciers. We will further provide advice regarding the optimal complexity of modeling strategies regarding regional-scale glacier modeling, particularly of tidewater glaciers.

除了巨大的主冰盖，格陵兰还有大量小得多的外围冰川。它们对格陵兰整体质量变化的贡献远远超过了它们在冰块和表面积中所占的份额。由于它们大多位于岛屿沿岸的山区，这些冰块的数值模式需要考虑足够的空间分辨率，而冰盖模式无法实现这一点。潮水冰川对总质量损失的贡献尤其大。2003至2008年间，周边冰川占格陵兰岛总冰量损失的14%。它们对海平面上升的贡献预计在未来会增加，目前可用的预测表明，在RCP 8.5的强迫下，21世纪外围冰川的冰量损失高达50%。外围冰川质量变化存在强烈的空间差异，反映了来自大气和海洋的强迫机制的复杂组合。然而，目前可用的能够计算区域尺度冰川质量变化的模型中，没有一个明确包括潮水冰川海洋末端的锋面消融过程的海洋强迫。除了两个模型外，没有一个模型考虑过任何正面消融过程。因此，到目前为止，还没有关于格陵兰外围潮水冰川正面消融的过去、现在或未来的估计。该项目的目的是预测21世纪格陵兰外围冰川在CMIP6整体的强迫下的未来演变，并特别关注潮水冰川。我们将量化它们的淡水排放和对海平面上升的贡献。我们将扩展开放全球冰川模型(OGGM)，将海洋强迫包括在其锋面消融模块中。这将得到大气和海洋边界条件的专用缩小尺度例程的协助。我们将评估OGGM在应用不同尺度的强迫数据方面的表现，以确定从大天气尺度向外围冰川较小局部尺度的优化尺度过渡是否能够以及在多大程度上能够提高模型的性能。该项目的成果将加深对海洋和大气对格陵兰周边冰川演化的影响的了解。我们将进一步提供关于区域规模冰川建模，特别是潮水冰川建模战略的最佳复杂性的建议。