Title: Exploring the Key Features of Tropical Cyclogenesis
Lecturer: Prof. Zhuo Wang (Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign)
Inviter: Prof. Zhemin Tan
Time: Monday, Jul 8, 2019 at 10:00AM
Venue: Lecture Hall D103, School of Atmospheric Sciences
Abstract：Cloud patterns in satellite imagery are routinely used to estimate tropical cyclone intensity (i.e., the Dvorak technique). A similar technique, however, is not available for tropical cyclogenesis because of our inadequate understanding of convective evolution during tropical cyclone formation. This hinders the effective use of satellite data in predicting tropical cyclogenesis. Key features of convection leading up to tropical cyclogenesis are investigated through the analysis of infrared (IR) brightness temperature(Tb) data in the framework of the marsupial paradigm. More than 150 named tropical cyclones over the Atlantic are examined, and our analyses suggest that convection intensity or area is not a key feature of convection for tropical cyclogenesis. In particular, a small and weak convective system is not necessarily associated with a weak vortex. Instead, organized convection near the circulation center is a key feature of convection for tropical cyclogenesis, and emphasizing convective intensity or frequency without considering the spatial pattern may be misleading. Using reanalysis data and high-resolution numerical model simulations, I will further discuss the dynamical and thermodynamical conditions that promote convective organization and the contributions of different types of precipitation to tropical cyclogenesis.