CoDyPhy: Improved Coupling of Dynamics and Physics for understanding and modelling moist convection

CoDyPhy：改进动力学和物理耦合，用于理解和建模湿对流

• 批准号: NE/N013123/1
• 负责人: John Thuburn
• 金额: $ 94.11万
• 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: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FN013123%2F1
• 关键词: CoDyPhy; Improved; Coupling; Dynamics; Physics

Moist convection is the term used to describe the vertical transport within clouds whose buoyancy is produced by the latent heat released when water vapour condenses. Moist convection is one of the dominant processes affecting the weather and climate in Earth's atmosphere. However, despite decades of effort, there remain major challenges in representing convective systems in the computer models used for weather and climate prediction. Common errors and biases include an inability to simulate a physically correct equilibrium between convection and radiative cooling, an unrealistic diurnal cycle of convection over ocean and over tropical land, unrealistically fast and weak convectively-coupled large-scale waves in the tropics, spuriously strong intermittency of modelled convection in space and time, and the occurrence of excessively violent `grid point storms' at the scale of the model grid.The proposed project aims to improve our ability to represent moist convection in weather prediction and climate models. This will be achieved through an improved understanding of how convection interacts with the atmospheric circulation on small and large scales, and through the development of a novel way of representing convection in numerical models.The interaction of convection with the atmospheric circulation is extremely complex and poorly understood. It involves many different feedback mechanisms, including large scale dynamics and transport, the atmospheric boundary layer and surface fluxes, and radiative processes. Our work will focus on tropical circulations: the Hadley circulation and InterTropical Convergence Zone, the Walker circulation, and convectively coupled waves. We will improve understanding of these interactions by using a simplified model of the global circulation to carry out carefully controlled hypothesis testing experiments and sensitivity tests. The aim here is not to simulate these circulations as accurately as possible, but to improve understanding by isolating the most important processes, diagnosing mechanisms, and quantifying sensitivities. This modelling work will be complemented by the development of a new theoretical model describing the interaction of convection with the atmospheric boundary layer and the larger scale circulation. This new theoretical model will be applied to understanding the role of the boundary layer in setting the structure of the Walker circulation. A third strand of this work will be to use theory and numerical models to understand the role of the boundary layer in influencing the diurnal cycle of convection.Global weather forecast models and climate models currently use grid resolutions coarser than 10km and of order several 10's of km, respectively. The so-called `dynamical core' of the model predicts the evolution of wind and temperature fields at these resolved scales. Typical convective clouds, however, have a horizontal scale of order 1km. Therefore, such models cannot resolve individual convective clouds. Instead, convection is represented by a subgrid model or `parameterization' scheme that attempts to model the effects of convection on the resolved scales. Here we propose a new approach to representing convection, in which separate wind and temperature fields for non-convecting fluid and convecting fluid are predicted by the dynamical core. We will extend the theoretical understanding of this two-fluid model, we will implement it in a three-dimensional computer model, and we will evaluate its performance in a series of tests of increasing complexity. This new representation of convection has the potential to overcome several long-standing limitations of conventional convection schemes.

湿润对流是用来描述云层内的垂直输送的术语，云层的浮力是由水蒸气凝结时释放的潜热产生的。湿对流是影响地球大气天气和气候的主要过程之一。然而，尽管经过了几十年的努力，在用于天气和气候预测的计算机模式中表示对流系统仍然存在重大挑战。常见的错误和偏差包括无法模拟对流和辐射冷却之间的物理正确平衡，海洋和热带陆地上对流的日循环不切实际，热带地区对流耦合的大尺度快速和弱波不切实际，模拟对流在空间和时间上的强间歇性虚假，以及在模型网格尺度上发生的过于猛烈的“网格点风暴”。提出的项目旨在提高我们在天气预报和气候模式中表示潮湿对流的能力。这将通过提高对对流如何在小尺度和大尺度上与大气环流相互作用的理解，以及通过发展一种在数值模式中表示对流的新方法来实现。对流与大气环流的相互作用是极其复杂的，人们对它知之甚少。它涉及许多不同的反馈机制，包括大尺度动力学和输运、大气边界层和地表通量以及辐射过程。我们的工作将集中在热带环流：哈德利环流和热带辐合带，沃克环流和对流耦合波。我们将利用一个简化的全球环流模式，进行精心控制的假设检验实验和敏感性试验，以增进对这些相互作用的了解。这里的目的不是尽可能准确地模拟这些循环，而是通过分离最重要的过程、诊断机制和量化敏感性来提高理解。这项模拟工作将由描述对流与大气边界层和大尺度环流相互作用的新理论模型的发展来补充。这个新的理论模型将被应用于理解边界层在设定沃克环流结构中的作用。这项工作的第三个方面将是使用理论和数值模型来理解边界层在影响对流日循环中的作用。全球天气预报模型和气候模型目前使用的网格分辨率分别大于10公里和几十公里。该模式的所谓“动力核心”预测了这些已确定尺度上风场和温度场的演变。然而，典型的对流云的水平尺度约为1km。因此，这种模式不能解析单个的对流云。相反，对流是用一个子网格模型或“参数化”方案来表示的，该方案试图在确定的尺度上模拟对流的影响。本文提出了一种新的对流表示方法，即利用动力核分别预测非对流流体和对流流体的风场和温度场。我们将扩展这种双流体模型的理论认识，我们将在三维计算机模型中实现它，我们将在一系列越来越复杂的测试中评估它的性能。这种对流的新表示有可能克服传统对流方案的几个长期限制。

项目成果

Diagnosing Coherent Structures in the Convective Boundary Layer by Optimizing Their Vertical Turbulent Scalar Transfer

通过优化垂直湍流标量传递来诊断对流边界层中的相干结构

• DOI: 10.1007/s10546-019-00480-1
• 发表时间: 2019
• 期刊: Boundary-Layer Meteorology
• 影响因子: 4.3
• 作者: Efstathiou G

Characterizing Convection Schemes Using Their Responses to Imposed Tendency Perturbations

• DOI: 10.1029/2021ms002461
• 发表时间: 2021-01
• 期刊: Journal of Advances in Modeling Earth Systems
• 影响因子: 6.8
• 作者: Y. Hwong;S. Song;S. Sherwood;A. Stirling;C. Rio;R. Roehrig;C. L. Daleu;R. Plant;D. Fuchs;P. Maher;L. Touzé‐Peiffer

Consistent and flexible thermodynamics in atmospheric models using internal energy as a thermodynamic potential. Part II: Non-equilibrium regime

使用内能作为热力学势的大气模型中一致且灵活的热力学。

• DOI: 10.1002/qj.4373
• 发表时间: 2022
• 期刊: Quarterly Journal of the Royal Meteorological Society
• 影响因子: 8.9
• 作者: Bowen P

The Flexible Modelling Framework for the Met Office Unified Model (Flex-UM, part of the UM 12.1 release)

英国气象局统一模型的灵活建模框架（Flex-UM，UM 12.1 版本的一部分）

• DOI: 10.5194/gmd-2021-193
• 发表时间: 2021
• 作者: Maher P

Model Hierarchies for Understanding Atmospheric Circulation

• DOI: 10.1029/2018rg000607
• 发表时间: 2019-05
• 期刊: Reviews of Geophysics
• 影响因子: 25.2
• 作者: P. Maher;E. Gerber;B. Medeiros;T. Merlis;S. Sherwood;A. Sheshadri;A. Sobel;G. Vallis;A. Voigt;P. Zurita‐Gotor