The Evolution of Dropsonde-Derived Kinematic and Thermodynamic Structures in Developing and Nondeveloping Atlantic Tropical Convective Systems

The processes by which tropical cyclones evolve from loosely organized convective clusters are still poorly understood. Because of the data-sparse regions in which tropical cyclones form, observational studies of tropical cyclogenesis are often more difficult than studies of land-based convective phenomena. As a result, many studies of tropical cyclogenesis are limited to either a few case studies or rely on simulations. The 2010 PREDICT and GRIP field experiments have provided a new opportunity to gain insight into these processes using unusually dense observations in both time and space. The present study aims at using these recent datasets to perform a detailed analysis of the three-dimensional evolution of both kinematic and thermodynamic fields in both developing and nondeveloping tropical convective systems in the western Atlantic. Five tropical convective systems are analyzed in this study: two nondeveloping, two developing, and one dissipating system. Although the analysis necessarily includes only a very limited number of cases, the results suggest that the convectively active nondeveloping systems and developing systems examined here have similar kinematic structures. The most notable difference is the distribution of humidity and the impacts this distribution has on the thermodynamics of the system. Displacements between the upper-level warm anomaly, responsible for midlevel vorticity generation, and the midlevel vorticity maximum are observed in both developing and nondeveloping cases. In the nondeveloping case the displacement appears to be caused by mid- and upper-level dry air. Further work is needed to fully understand the cause of these displacements and their relation to tropical cyclogenesis.