The Evolution of Dropsonde-derived Vorticity in Developing and Non-developing Tropical Convective Systems

The process by which tropical cyclones evolve from loosely organized convective clusters into well organized systems is still poorly understood. Due to the data sparse regions in which tropical cyclones form, observational studies of tropical cyclogenesis are often more difficult than similar studies of land-based phenomena. As a result, many studies of tropical cyclogenesis are limited to either a few case studies or are forced to rely on simulations to examine the genesis process. The recent PREDICT and GRIP field experiments have provided a new opportunity to gain insight into these processes using unusually dense observations.

The present study aims at using this new data in conjunction with data from previous field experiments to perform a detailed analysis of the three-dimensional structural evolution of vorticity in both developing and non-developing tropical convective systems. Additionally, observations of kinematic and thermodynamic fields, (e.g. temperature, moisture, and divergence) are used to aid the explanation of structural changes in the vorticity fields. The system-wide evolution is determined by examining the time evolution of composited mean dropsonde soundings. Further, the temporal evolution of sub-system processes, which are minimized or removed as a result of the compositing process, are identified in isobaric surface plots and cross-sections. Finally, as a secondary goal, this study hopes to provide insight into the theoretical and operational implications of the observed vorticity evolution.