Toward Improved Understanding of Rapid Intensification (RI) of Tropical Cyclones

University Of Hawaii, Honolulu

Investigators

Abstract

The rapid intensification (RI), which involves interactions between the inner core dynamics and the large-scale environment and among different spatial and temporal scales, is still one of the least understood phases of a tropical cyclone (TC). Previous studies have already shown that the rapid formation of a warm core in the upper troposphere is the key to the RI onset of a TC. In this study, processes that lead to the rapid formation of the upper-tropospheric warm core in TCs will be explored through on idealized and real-case simulations and diagnostic and budget analyses using cloud-resolving models. In particular, the following three scientific questions will be addressed: 1) Given favorable tropical ocean conditions, is the intensification rate of a TC externally or internally determined and can an environmental flow or synoptic-scale forcing increase the intensification rate that a TC could have without these forcing? 2) How do the three-dimensional (3D) structure (including the size) and intensity of a TC vortex determine the efficiency of the upper-tropospheric warming and thus the intensification rate of the TC itself? 3) How are convective bursts and hot towers triggered and how do they lead to the upper tropospheric warming over the storm core prior to and during the RI? To answer these questions, we will use the TC model (TCM4) developed by the PI and the advanced Weather Research and Forecasting (WRF) model developed at National Center for Atmospheric Research (NCAR) to conduct a series of idealized and real-case simulations and perform diagnostic and budget analyses to verify our hypotheses, identify the physical mechanisms responsible for the RI. Intellectual Merit: Results from this research will improve our understanding of the dynamics of the RI of tropical cyclones and factors that determine the potential intensification rate of a TC. Broader Impacts: The research will lead to a set of parameters/factors that determine the potential intensification rate of tropical cyclones. This will contribute to improved ability to predict TC intensity change. Results from this research will also demonstrate what parameters of the three-dimensional structure of the initial TC are critical to the intensity prediction by numerical models, thus potentially leading to improved prediction of TC structure and intensity. In the course of this project, a female graduate student will receive training in the science of TCs, especially in the area of TC dynamics and modeling.