Energy Flow in a High Resolution 3D Tropical Cyclone Simulation

Mature tropical cyclones have been realistically simulated by both axisymmetric models and three-dimensional models. However, observed tropical cyclones have significant asymmetries in the form of rain bands and vortical hot towers (VHTs). The role of asymmetries in rapid intensification of a nascent tropical cyclone remains unknown. Recent work has implicated VHTs as the preferred source of PV anomalies in a strengthening tropical cyclone; however, further studies dispute this hypothesis as a driver for rapid intensification. In this work we explore the Lorenz energy cycle in a 3-D tropical cyclone simulation. Using a 2 km resolution anelastic equation model, the mean flow and eddy energy conversions between available potential energy (APE) and kinetic energy (KE) are compared over the storm's lifetime. The motivation is to determine whether eddy-driven up-gradient energy flow is a dominant means of strengthening a simulated tropical cyclone. Results indicate that, in a simulation with no background shear, asymmetries in fact draw energy from the storm; eddy KE is primarily powered by mean KE, weakening the mean flow. This is consistent with the results of Kwon and Frank (2008). The effect of adding shear to the model will also be also examined.