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

GSTDTAP

项目编号	NE/N013123/1
	CoDyPhy: Improved Coupling of Dynamics and Physics for understanding and modelling moist convection
	[unavailable]
主持机构	University of Exeter
项目开始年	2016
	2016-08-01
项目结束日期	2019-07-31
资助机构	UK-NERC
项目类别	Research Grant
国家	英国
语种	英语
英文摘要	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.
来源学科分类	Natural Environment Research
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/86292
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	[unavailable].CoDyPhy: Improved Coupling of Dynamics and Physics for understanding and modelling moist convection.2016.