Multi-scale modelling of the ocean beneath ice shelves

冰架下海洋的多尺度建模

基本信息

批准号：
NE/G018391/1
负责人：
Matthew Piggott
金额：
$ 45.05万
依托单位：
Imperial College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FG018391%2F1
关键词：
Multi scale modelling ocean beneath

项目摘要

Quantitative prediction of future sea level is currently impossible because we lack an understanding of how the mass balance of the Earth's great ice sheets can be affected by climate change. Chief among the uncertainties are how changes in ocean circulation and/or temperature will influence the thickness and extent of the ice shelves and how the outflow from the ice sheet will change in response. Observations of the ocean under ice shelves are very sparse and difficult to obtain. Hence, numerical modelling has been used to provide insight into the structure and dynamics of the ocean flow in ice shelf cavities, as well as their influence on the larger scale. However, the complexities associated with this application means that models based upon hydrostatic dynamics, uniform mesh resolution and a layered structure in the vertical, may be improved upon. These complexities include the presence of a grounding line where the water column depth goes to zero under ice deep below mean sea level. The importance of this very limited region to the ice shelf above, and the associated grounded ice sheet, is massive but this is exactly the point where conventional models need to make the largest compromises in representing the real world. Also, the shape of the base of the ice shelf, and the steep change at the front between the ice and the open ocean, place important constraints on the ocean dynamics and hence they need to be represented well in a model in a similar manner to sea floor bathymetry. This, along with the representation of critical buoyancy driven processes that may be of small scale, points towards the use of non-uniform resolution in both the horizontal and vertical directions. In this project we will adapt our state-of-the-art numerical model to study the ocean circulation in the cavities beneath floating ice shelves. Unstructured and anisotropic dynamically-adaptive mesh methods in three dimensions will allow simulations with a resolution and geometric flexibility that is greater than has been possible before. Model developments will be benchmarked against earlier model results and validated on a hierarchy of test problems. Real world applications under the Filchner-Ronne and Pine Island Glacier ice shelves will be used to calibrate and validate the model against observational (including new Autosub) data. Highly timely new science will be preformed in these areas, and this project will also be an important step towards the inclusion of ice shelf cavities in global scale ocean models of the future. The final result will be an improved understanding of the physical processes occurring under ice shelves, and a powerful tool that will enable the explicit inclusion of ice shelves in global scale ocean and climate models of the future. This project fits well with NERC strategy. In particular the prediction of the future contribution of the ice sheets to sea level rise is seen as a high priority goal that cuts across the themes of Climate Systems, Earth System Science and Natural Hazards. Development of the next generation climate models is also a priority for the Climate Systems and Technologies themes.

目前对未来海平面的定量预测是不可能的，因为我们缺乏了解地球巨大冰盖的质量平衡如何受到气候变化的影响。不确定性的主要是海洋循环和/或温度的变化如何影响冰架的厚度和程度，以及从冰盖中流出的反应将如何变化。在冰架下对海洋的观察非常稀疏，难以获得。因此，数值建模已被用来洞悉冰架腔中海洋流的结构和动力学及其对较大规模的影响。但是，与此应用相关的复杂性意味着基于静液压动力学，均匀的网格分辨率和垂直结构的模型可以改善。这些复杂性包括存在地面线，其中水柱的深度在平均海平面以下的冰下下降到零。这个非常有限的区域对上面的冰架以及相关的冰盖的重要性是巨大的，但这正是传统模型在代表现实世界中最大的妥协所需的点。同样，冰架底部的形状以及冰和开阔海洋之间的前部的陡峭变化，对海洋动力学的重要约束，因此需要以类似于海底测深的方式以类似的模型来很好地代表。这是临界浮力驱动的过程的表示，可能是小规模的，指向在水平和垂直方向上使用不均匀的分辨率。在这个项目中，我们将调整我们的最先进的数值模型，以研究浮冰架下的空腔中的海洋循环。在三个维度上的非结构化和各向异性动态自适应网格方法将允许模拟具有分辨率和几何柔韧性，比以前更大。模型开发将针对早期的模型结果进行基准测试，并根据测试问题的层次结构进行验证。 Filchner-Ronne和Pine Island冰川冰架下的现实世界应用将用于校准和验证模型，以防止观察性（包括新的AutoSub）数据。高度及时的新科学将在这些领域中得到预知，该项目也将是将冰架腔纳入未来全球规模海洋模型中的重要一步。最终的结果将是对冰架下发生的物理过程的了解，以及一种强大的工具，可以显式地将冰搁在全球规模的海洋和未来气候模型中。该项目非常符合NERC策略。特别是，对冰盖对海平面上升的未来贡献的预测被视为跨越气候系统，地球系统科学和自然危害的主题的高优先目标。下一代气候模型的开发也是气候系统和技术主题的优先事项。