Eye Formation and Energetics in a Dry Model of Hurricane-Like Vortices

Abstract

Abstract We investigate the mechanism for eye formation in hurricane-like vortices, using a formulation adapted from Oruba, Davidson, and Dormy. Numerical simulations are performed using an axisymmetric model of dry rotating Rayleigh–Bénard convection under the Boussinesq approximation. The fluxes of heat and momentum at the sea surface are described using the bulk aerodynamic formula. A simplified model for radiative cooling is also implemented. We find that the mechanism for eye formation introduced in Oruba et al., relying on vorticity stripping from the boundary layer, is robust in dry hurricane-like vortices. Furthermore, with these boundary conditions, the structure of the flow is closer to the flow of actual tropical cyclones. The applicability of this mechanism to the moist case however remains uncertain and deserves further study. Finally, energy budgets, obtained either by a heat engine approach or by a direct estimation of the work of buoyancy forces, are investigated. They provide estimations of the surface wind speed as a function of the controlling parameters. Significance Statement Tropical cyclones (also known as hurricanes or typhoons, depending on their location) are life-threatening and devastating atmospheric vortices. Their impact worsens with sea level rise and increasing coastal population. Here, we explore, using idealized models, the physics behind the formation of an eye (the quiet and typically clear region at the center of these storms). We then investigate the controlling parameters for the amplitude of the strongest winds in the model, using energy constraints, and compare them to what is observed in actual tropical cyclones.