Diabatic Ekman Turbulence

非绝热艾克曼湍流

• 批准号: 0750660
• 负责人: David Schecter
• 金额: $ 36.97万
• 依托单位: NorthWest Research Associates, Incorporated
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-03-01 至 2012-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0750660&HistoricalAwards=false
• 关键词: Diabatic; Ekman; Turbulence

The circulation of the tropical atmosphere is, in part, organized by regions of strong rotation, or vortical turbulence. Some of these regions develop into tropical cyclones. A fundamental fluid dynamical model will be developed, which captures the essential processes that allow coherent vortical structures to emerge in the tropical atmosphere, the diabatic Ekman turbulence model. Unlike simpler models (shallow water or two-level quasigeostrophic) it can represent two processes that are necessary for the formation of tropical cyclones, Ekman pumping and wind-induced surface heat exchange (WISHE). Preliminary numerical experiments using this model demonstrate that diabatic Ekman turbulence can spontaneously self-organize into intense hurricane-like vortices. Two lines of research will be carried out. The first is to study the emergence of coherent structures, focusing on the predictability of the frictional radiative convective equilibrium that is achieved with a given parameter setting. Preliminary results indicate that the same parameter settings can result in discrete quasi-equilibrated states with different numbers and intensities of vortices. The dependence of the equilibrated states and their predictability on the initial conditions and the parameter settings will be explored. The second activity is a study of the dynamical mechanisms that operate in the diabatic Ekman turbulence model, including those that give rise to the intensification of individual cyclones, the processes that produce vortex mergers and vortex symmetrization, and the interactions between waves and vortices.Broader impacts of this work are in its relevance to the development and growth of tropical cyclones, with possible implications for their statistical prediction. The model will be developed as an educational tool. A student will be involved in the research through a collaboration with the University of Washington.

热带大气的环流部分是由强旋转或涡旋湍流区域组织的。其中一些地区发展成热带气旋。将开发一个基本的流体动力学模型，该模型捕捉了热带大气中出现相干涡旋结构的基本过程，即非绝热Ekman湍流模型。与较简单的模式（浅水模式或两层准地转模式）不同，它可以代表热带气旋形成所必需的两个过程，即埃克曼抽吸和风引起的表面热交换（WISHE）。初步的数值实验表明，非绝热Ekman湍流可以自发地自组织成强烈的飓风般的漩涡。将开展两方面的研究。第一个是研究相干结构的出现，重点是在给定参数设置下实现的摩擦辐射对流平衡的可预测性。初步结果表明，相同的参数设置可以导致不同数量和强度的涡的离散准平衡状态。将探讨的依赖性的平衡状态和它们的可预测性的初始条件和参数设置。第二项活动是研究非绝热Ekman湍流模式中的动力机制，包括导致单个气旋增强的机制、产生涡旋合并和涡旋对称化的过程以及波和涡旋之间的相互作用，这项工作的更广泛影响在于它与热带气旋的发展和增长的相关性，这可能会影响他们的统计预测。该模型将作为一种教育工具加以开发。一名学生将通过与华盛顿大学的合作参与这项研究。