When will cyclogenesis commence given a favorable tropical environment?

摘要

A numerical diagnosis of tropical cyclogenesis in a quiescent, rotating environment is presented to suggest an answer to the above question. Our research approach employs near-cloud-resolving numerical simulations to quantitatively analyze helical self-organization of moist-convective atmospheric turbulence. The simulations permit a diagnosis of cyclogenesis when the primary and secondary circulations in a forming hurricane vortex become linked by special convective coherent structures – Vortical Hot Towers (VHTs). The VHTs are argued to be intrinsic elements of the turbulent vortex dynamo in the tropical atmosphere of the Earth. It is discussed how the generated linkage makes the nascent vortex an integral helical system, supporting a positive feedback between the circulations. The feedback is sustained by only modest fluxes of latent heat from the underlying ocean, convective instability and vortical convection. The feedback indicates a release of potential energy that is converted into kinetic energy of developing large-scale helical vortex. Energy exchange between the primary and secondary circulation and their further mutual intensification is inferred from the numerical experiments.