Computational Framework for Multi-Scale Environmental Modelling

该提案的总体目的是耦合和优化两个现有的计算模型（帝国流动性和剑桥ATHAM）。Cambridge-ATHAM模式是一个高分辨率的大气模式，对载有颗粒的羽流有特殊规定。物理参数化存在于与羽流和云相关的广泛应用中。ATHAM模式已被证明是非常好的工作在对流问题中的地形的影响和与大尺度流的相互作用是次要的。然而，对流经常在锋面系统内发展，这些锋面系统是大规模流动的一部分。由于表面的不均匀性，地形经常提供扰动和差异加热，从而引发对流。目前，ATHAM是一个有限区域的模式，制定了一个笛卡尔网格，使大规模的流动的发展无法模拟。垂直坐标不遵循地形，因此只能粗略地表示地形。然而，FLUIDITY包含最先进的并行自适应网格方法，能够最佳地解决流动，同时通过适当的元素对（如P1_DG-P2元素）保持关键平衡，可以准确地表示地转/流体静力平衡。通过将ATHAM与FLUIDITY相结合，ATHAM的垂直分辨率限制将被克服，从而允许研究与全球气候模式相关的一系列新问题。合并后的全球模型将能够捕捉感兴趣区域内的大尺度流动和小尺度特征（感兴趣区域将使用100米或更高量级的高空间分辨率，这些区域以外的粗分辨率将具有100公里量级的空间分辨率，以及它们之间的过渡区）。动态自适应网格能力将允许网格分辨率根据当地流动条件进行调整。非结构化网格将使地形能够以所需的精度表示。从长远来看，这种合作将优化我们的建模技术，从而产生一个稳定，灵活和用户友好的计算环境，这可能有助于通过国内和国际上的其他学术工业团体进行传播。

The overall purpose of the proposal is to couple and optimize two existing computational models (Imperial-Fluidity and Cambridge-ATHAM). The Cambridge-ATHAM model is a high-resolution atmospheric model with special provisions for particle-laden plumes. Physical parameterisations exist for a wide range of plume and cloud relevant applications. ATHAM model has proven to work very well in convection problems where the influence of the topography and the interaction with the large-scale flow are of secondary importance. However, convection often develops within frontal systems that are part of the large-scale flow. Topography often provides the perturbation and differential heating due to surface inhomogeneities that can trigger convection. At the moment, ATHAM is a limited area model formulated for a Cartesian grid so that the development of the large-scale flow cannot be simulated. The vertical coordinate does not follow the terrain so that only a crude representation of topography is possible. FLUIDITY, however, contains state of the art parallel adaptive mesh methods, that are able to optimally resolve the flows, whilst maintaining key balances through appropriate element pairs like the P1_DG-P2 element, which can exactly represent geostrophic/hyrdostatic balance. By combining ATHAM with FLUIDITY, the vertical resolution limitation of ATHAM will be overcome, thus allowing a new range of problems associated with global climate models to be investigated. The combined global model will be able to capture large-scale flow as well as fine-scale features in areas of interest (high spatial resolution in the order of 100m or higher will be used in areas of interest, coarse resolution outside of those areas will have spatial resolutions in the order of 100km and transition zones between them). A dynamically adaptive grid capability will allow the mesh resolution to be adjusted according to the local flow conditions. The unstructured grid will enable topography to be represented to the desired accuracy. Longer term this collaboration will optimise our modelling technologies resulting in a stable, flexible and user-friendly computational environment that may help the dissemination through other academic industrial groups, nationally and internationally.