The formation of tropical storms and hurricanes, known as tropical cyclogenesis, is a complex process involving interactions between the large-scale environment and a smaller-scale atmospheric disturbance passing through. There have been multiple theories developed to try to describe the pathway that a disturbance takes on its road to becoming a tropical storm. In this project, researchers will use advanced, high-resolution numerical modeling to analyze the processes involved in two of these pathways. Improved knowledge of how tropical cyclones form will aid forecasters and improve public safety, especially in the cases where small storms develop very close to populated areas. This award will also provide a training opportunity for a graduate student.
The first pathway to tropical cyclogenesis is characterized by a spin up of cyclonic surface winds and vorticity building in the center of deep convective towers. The second is characterized by a mid-level vortex that is followed by a small surface concentrated vortex near the center of the large scale circulation. The research plan is to conduct idealized numerical experiments using the Regional Atmospheric Modeling System (RAMS) with new riming and surface flux schemes and the Weather Research and Forecasting (WRF) model with moving nested grids. The main objectives that the project will address are to: 1) Determine the physical mechanisms responsible for the development of strong mid-level vortices and the conditions that favor their occurrence, 2) Identify the processes leading to the formation of a small surface concentrated vortex, and 3) Determine the effect of vertical wind shear, including a mean flow, on the pathway taken to tropical cyclogenesis.
