Mesoscale Vortex Interactions in Tropical Systems

预测和理解飓风的形成是大气科学中最具挑战性的问题之一。预测飓风的困难部分来自发展中系统中尺度涡旋的复杂相互作用。本研究项目旨在阐明发展中系统中尺度涡旋相互作用的物理特性，以及这种相互作用对飓风形成的影响。将处理下列基本问题：湿对流中尺度涡旋合并的条件和主要机制是什么？合并发生的时间尺度是什么？地面风的增强率如何取决于中尺度涡旋相互作用的变率，例如是否发生合并？先前的中尺度涡旋相互作用如何影响新形成的热带风暴或飓风的大小、强度和不对称结构？上述问题在过去已经得到解决，但只是在狭隘的案例研究的背景下，或者使用简化模型进行更广泛的研究，这些模型对手头问题的适用性存在问题。目前的调查将包括使用最先进的云系统解析数值模型精心设计的计算研究。这些研究将涉及涡旋参数的变化，大气的湿热力学状态，涡旋所在的更广泛流动的性质，以及调节海气相互作用的参数。附加的数值实验将检验结果对微物理和亚网格湍流参数化细节的敏感性。智力优势：该项目将导致对湿对流中尺度涡旋相互作用及其在发展热带系统中的影响的全面、定量的理解。如前所述，该领域的知识目前仅限于不同的案例研究，以及缺乏现实性的简化建模研究。在一般意义上，这个项目的成果不仅将推进动力气象学，而且将推动基础流体动力学更广泛的领域。更广泛的影响：该项目的结果将提高目前对准确的飓风预测何时需要在预报模拟中精确初始化或同化中尺度涡旋的理解。减少飓风预测的不确定性对于规划海上活动和沿海社区的安全措施显然很重要。该项目的教育部分将包括对博士后研究员的高级培训/指导，以及在大学研讨会上的演讲。该项目的结果将通过期刊出版物、会议报告和研究网页影响更广泛的大气科学和物理界。

Predicting and understanding hurricane formation is one of the most challenging problems in atmospheric science. A part of the difficulty in predicting hurricanes stems from the complex interactions of mesoscale vortices in developing systems. This research project aims to elucidate the physics of mesoscale vortex interactions in developing systems and the consequences of such interactions on the formation of hurricanes. The following fundamental questions will be addressed:1. What are the conditions and prevailing mechanisms for the merger of moist-convective mesoscale vortices, and what is the time-scale for merger to occur?2. How does the intensification rate of surface winds depend on the variability of mesoscale vortex interactions, such as whether or not merger takes place?3. How do prior mesoscale vortex interactions affect the size, intensity and asymmetric structure of a young tropical storm or hurricane?The above issues have been addressed in the past, but only in the context of narrow case studies, or somewhat broader studies using simplified models with questionable applicability to the problem at hand.The present investigation will consist of carefully designed computational studies using a state-of-the-art cloud system resolving numerical model. These studies will involve variation of the vortex parameters, the moist-thermodynamic state of the atmosphere, the properties of the broader flow in which the vortices are situated, and the parameters regulating air-sea interaction. Additional numerical experiments will examine the sensitivity of results to details of the microphysics and subgrid turbulence parameterizations.Intellectual Merit: This project will lead to a comprehensive, quantitative understanding of moist-convective mesoscale vortex interactions and their consequences in developing tropical systems. As noted earlier, knowledge in this area is currently limited to disparate case studies, and simplified modeling studies with insufficient realism. In a general sense, the results of this project will not only advance dynamic meteorology, but also the broader field of fundamental fluid dynamics.Broader Impacts: The results of this project will improve current understanding of when accurate hurricane prediction requires the accurate initialization or assimilation of mesoscale vortices in forecast simulations. Reducing the uncertainty of hurricane prediction is clearly important for planning maritime activities and safety measures for coastal communities. The educational components of this project will include the advanced training/mentoring of a postdoctoral researcher, and presentations at university seminars. The results of this project will impact the broader atmospheric science and physics communities through journal publications, conference presentations, and a research web page.