NGWCP - Atmospheric model dynamical core

NGWCP - 大气模型动力核心

基本信息

批准号：
NE/I021136/1
负责人：
John Thuburn
金额：
$ 17.29万
依托单位：
UNIVERSITY OF EXETER
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2011
资助国家：
英国
起止时间：
2011 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FI021136%2F1
关键词：
NGWCP Atmospheric model dynamical core

项目摘要

At the heart of a weather prediction or climate simulation model is a `dynamical core' that solves the equations describing the fluid dynamics and thermodynamics of the atmosphere on the scales that can be resolved. The dynamical core of the current Met Office Unified Model for weather and climate prediction (the `New Dynamics') and its planned successor (`ENDGame') use highly efficient and accurate methods that exploit the structure of a longitude-latitude grid. However, several aspects of these schemes involve non-local data communication, particularly near the poles of the grid. Such non-local communication is expected to become a serious performance and scalability bottleneck on future massively parallel computer architectures, for which communication between processors is disproportionately slow compared to the calculation itself. It is therefore imperative to examine alternative, quasi-uniform, grids, with much reduced communication demands, as a potential basis for a future atmospheric model dynamical core. The proposed project will examine some of the leading candidate alternative grids. The properties of the candidate grids will be examined through a combination of theoretical analysis and numerical calculations using simplified equation sets. One requirement is for accurate wave propagation. The ideal scheme should capture the frequencies of all resolved waves as well as possible and should not support any unphysical `computational modes'. This will be examined theoretically in idealised cases where the calculation is tractable, and numerically in more complex cases. If a candidate scheme is found to support computational modes, methods for controlling them will be examined. Another set of essential requirements relate to conservation of mass and energy, and that the scheme should respect basic geometrical requirements such as the fact that the gradient of the geopotential should generate no local rotation (vorticity) in the fluid. Also among these requirements is the need for the scheme to be able to support balanced flow, since the atmosphere is observed to be close to balance on large scales. Again, these requirements will be examined through a combination of theoretical analysis and numerical testing. Finally, all of the candidate alternative grids have the potential for the numerical approximations to lead to the grid structure being reflected in persistent errors in the numerical solution, so called `grid imprinting'. Test cases will be developed and applied to quantify the grid imprinting tendencies of the various candidate grids.

天气预报或气候模拟模型的核心是一个“动力核心”，它在可解析的尺度上求解描述大气流体动力学和热力学的方程。当前气象局天气和气候预测统一模型（“新动力学”）及其计划的后续模型（“ENDGame”）的动力核心采用高效、准确的方法，利用经纬度网格的结构。然而，这些方案的几个方面涉及非本地数据通信，特别是在电网两极附近。这种非本地通信预计将成为未来大规模并行计算机架构的严重性能和可扩展性瓶颈，因为与计算本身相比，处理器之间的通信速度慢得不成比例。因此，有必要研究替代的、准均匀的网格，以大大减少通信需求，作为未来大气模型动力核心的潜在基础。拟议的项目将研究一些领先的候选替代网格。将通过理论分析和使用简化方程组的数值计算相结合来检查候选网格的属性。一项要求是精确的波传播。理想的方案应该尽可能捕获所有解析波的频率，并且不应该支持任何非物理的“计算模式”。这将在计算易于处理的理想情况下进行理论上的检验，并在更复杂的情况下进行数值检验。如果发现候选方案支持计算模式，则将检查控制它们的方法。另一组基本要求涉及质量和能量守恒，并且该方案应尊重基本几何要求，例如位势梯度不应在流体中产生局部旋转（涡度）。这些要求中还包括需要该方案能够支持平衡流动，因为观察到大气在大范围内接近平衡。同样，这些要求将通过理论分析和数值测试相结合的方式进行检验。最后，所有候选替代网格都有可能通过数值近似导致网格结构反映在数值解中的持续误差中，即所谓的“网格印记”。将开发并应用测试用例来量化各种候选网格的网格印记倾向。