Mesoscale Vortex Interactions in Tropical Systems

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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.