Fundamental Tropical Dynamics

Colorado State University, Fort Collins CO

Investigators

Abstract

This award is for the investigation and analysis of several topics related to the dynamics of tropical cyclones. The research team will use a combination of theory, numerical models, and observations to address longstanding questions, with a particular focus on tropical cyclone eyewall structures. The development of secondary eyewalls in tropical cyclones has a significant impact on the intensity of the storms and is a limiting factor on how well the intensity can currently be forecast. A successful project would lead to better understanding of the physics of the storms and how they can best be modeled, leading to an improvement in forecasts and public safety and economic benefits. In addition, the project will help to educate and train the next generation of research scientists. In this project, simplified dynamical theories will be developed using balanced model principles and potential vorticity arguments. The objectives of the proposal address the following fundamental research questions in tropical dynamics: 1) What is the distribution of subsidence in the hurricane eye? Is subsidence concentrated at the edge of the eye, thereby producing a warm-ring rather than a warm-core thermal structure? 2) Why is the ITCZ so thin, why does it form where it does, and what are its natural forms of oscillation? 3) Why do major hurricanes often form double eyewalls, what determines the locations of these eyewalls, and what dynamics are involved in the disintegration of the inner eyewall? 4) How do surface frictional effects in a moving hurricane break the circular symmetry of the eyewall and lead to crescent-shaped regions of intense eyewall convection? This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.