A Lagrangian Vertical Coordinate Dynamical Core for Global Atmospheric Modelling

全球大气建模的拉格朗日垂直坐标动力核心

基本信息

批准号：
NE/H006834/1
负责人：
John Thuburn
金额：
$ 31.82万
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：
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%2FH006834%2F1
关键词：
Lagrangian Vertical Coordinate Dynamical Core

项目摘要

The weather forecasts and climate predictions produced by the Met Office are based on a sophisticated computer model that numerically solves the equations of atmospheric dynamics and thermodynamics. The equations are solved by dividing the Earth's atmosphere up horizontally into cells based on a latitude-longitude grid and vertically into a number of layers or levels. The current Met Office model, and its successor (currently under development, known as ENDGame), define these levels to be at specified heights above the Earth's surface. An alternative would be to use so-called Lagrangian vertical levels, which, by definition move up and down with the fluid. There is some evidence from experiments with computer models around the world that using Lagrangian vertical levels could better capture air mass properties and the transport of moisture and other constituents, and improve the representation of the budget of energy and other important thermodynamic properties such as entropy. This, in turn, could lead to more accurate weather forecasts and more realistic climate simulations and predictions. With this motivation, the aim of the project is to develop a version of ENDGame that uses Lagrangian vertical levels, and carefully assess the extent to which any of the potential benefits have been realized. One of the disadvantages of Lagrangian vertical levels is that, as they move with the fluid, they eventually tilt and fold until they can no longer represent the state of the atmosphere accurately. This folding can take many hours or days high up in the atmosphere but can be much quicker near steep mountains or areas of thunderstorm activity. Therefore, to be used in a computer model, Lagrangian levels must be periodically re-initialized and the model winds and thermodynamic fields remapped to the re-initialized levels. A major part of the proposed work will involve investigating the best way to re-initialize and remap, so that the benefits of using the Lagrangian levels are not degraded. The culmination of the project will be a careful comparison of the transport and conservation properties of the standard ENDGame model using its height-based levels and the new version using Lagrangian levels. Apart from the different vertical levels used, these two models will be as similar as possible; the comparison will therefore be a clean test of the benefits (or otherwise) of the use of Lagrangian levels. Such a clean comparison has not been carried out before. The results will provide valuable information to the Met Office and to other groups around the world developing computer models of the atmosphere. Close contact with the Met Office throughout this project will ensure that, if the Lagrangian vertical coordinate is successful, then it can be readily implemented in the operational version of ENDGame.

英国气象局制作的天气预报和气候预测基于复杂的计算机模型，该模型可以对大气动力学和热力学方程进行数值求解。这些方程是通过将地球大气层水平划分为基于纬度-经度网格的单元并垂直划分为多个层或级别来求解的。当前的英国气象局模型及其后继模型（目前正在开发中，称为 ENDGame）将这些水平定义为距地球表面指定的高度。另一种方法是使用所谓的拉格朗日垂直水平仪，根据定义，垂直水平仪会随流体上下移动。世界各地计算机模型实验的一些证据表明，使用拉格朗日垂直水平可以更好地捕获空气质量特性以及水分和其他成分的传输，并改善能量预算和其他重要热力学特性（例如熵）的表示。反过来，这可能会带来更准确的天气预报和更现实的气候模拟和预测。出于这个动机，该项目的目标是开发一个使用拉格朗日垂直水平的 ENDGame 版本，并仔细评估任何潜在收益已实现的程度。拉格朗日垂直水平仪的缺点之一是，当它们随流体移动时，它们最终会倾斜和折叠，直到它们不再能够准确地表示大气状态。这种折叠在大气层高处可能需要数小时或数天的时间，但在陡峭的山脉或雷暴活动的地区可能会更快。因此，为了在计算机模型中使用，必须定期重新初始化拉格朗日水平，并将模型风和热力学场重新映射到重新初始化的水平。拟议工作的主要部分将涉及研究重新初始化和重新映射的最佳方法，以便不降低使用拉格朗日水平的好处。该项目的高潮将是使用基于高度的水平的标准 ENDGame 模型和使用拉格朗日水平的新版本的传输和保护属性进行仔细比较。除了使用的垂直高度不同之外，这两个模型将尽可能相似；因此，该比较将是对使用拉格朗日水平的好处（或其他）的干净测试。以前从未进行过如此清晰的比较。研究结果将为英国气象局和世界各地开发大气计算机模型的其他团体提供有价值的信息。在整个项目过程中与英国气象局的密切联系将确保，如果拉格朗日垂直坐标成功，那么它可以很容易地在 ENDGame 的操作版本中实施。