The Dynamics of Tropical Cyclones

The specific objectives of the current effort are: 1. To continue our study of the dynamical processes in tropical cyclones responsible for looping or erratic motion; 2. To continue the development of methods for (a) the introduction of synthetic tropical-cyclone-scale vortices in operational forecast models and (b) ensemble forecasting of tropical cyclones; 3. To continue a sensitivity study of track forecasts with a simple numerical model, focusing on different initialization strategies and using initial data sets from different forecast centres; 4. To continue our study of the dynamics of the extra-tropical transition of tropical cyclones with emphasis on idealized modelling; 5. To continue our study of tropical cyclone intensity change processes and motion in three dimensions via potential vorticity anomalies or vortex Rossby waves; 6. To elucidate the physical mechanisms underlying changes in hurricane structure and intensity, including rapid deepening and eyewall replacement cycles; 7. To diagnose hurricane track and intensity change as predicted by the Geophysical Fluid Dynamics Laboratory (GFDL) hurricane model using the technique of potential vorticity inversion; 8. To continue a numerical modelling study of tropical-cyclone trough interaction; 9. To continue a study of the factors which govern the size of tropical cyclones; 10. To continue a numerical modelling study of midget typhoons; and 11. To initiate a numerical and theoretical study of the spin down of tropical cyclone vortices; 12. To initiate collaboration with the German Weather Service (DWD) to improve the prediction of tropical cyclones with the DWD’s global model.