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.

目前无法对未来海平面进行定量预测，因为我们不了解气候变化如何影响地球大冰盖的质量平衡。其中最主要的不确定性是海洋环流和/或温度的变化将如何影响冰架的厚度和范围，以及冰盖的流出量将如何变化。对冰架下海洋的观测非常稀疏且难以获得。因此，数值模拟已被用来深入了解冰架空腔中洋流的结构和动力学，以及它们对更大尺度的影响。然而，与该应用相关的复杂性意味着基于流体静力动力学、均匀网格分辨率和垂直分层结构的模型可以得到改进。这些复杂性包括存在接地线，在平均海平面以下的冰层下，水柱深度为零。这个非常有限的区域对于上面的冰架以及相关的接地冰盖来说非常重要，但这正是传统模型在代表现实世界时需要做出最大妥协的地方。此外，冰架底部的形状，以及冰与公海之间前端的陡峭变化，对海洋动力学产生了重要的限制，因此需要以类似的方式在模型中很好地表示它们海底测深。这与可能是小规模的关键浮力驱动过程的表示一起，表明在水平和垂直方向上使用非均匀分辨率。在这个项目中，我们将采用最先进的数值模型来研究漂浮冰架下方空腔中的海洋环流。三维非结构化和各向异性动态自适应网格方法将允许以比以前更大的分辨率和几何灵活性进行模拟。模型开发将根据早期模型结果进行基准测试，并在测试问题的层次结构上进行验证。 Filchner-Ronne 和 Pine Island 冰川冰架下的实际应用将用于根据观测数据（包括新的 Autosub）校准和验证模型。非常及时的新科学将在这些领域进行，该项目也将是将冰架空腔纳入未来全球规模海洋模型的重要一步。最终结果将是加深对冰架下发生的物理过程的了解，并提供一个强大的工具，将冰架明确纳入未来的全球规模海洋和气候模型中。该项目非常符合NERC的战略。特别是，预测冰盖对海平面上升的未来贡献被视为一个高度优先的目标，涉及气候系统、地球系统科学和自然灾害等主题。开发下一代气候模型也是气候系统和技术主题的优先事项。