J. Atmos. Sci., in press.

Role of radiative-convective feedbacks in spontaneous tropical cyclogenesis in idealized numerical simulations

Allison A. Wing
Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY.

Suzana J. Camargo
Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY.

Adam H. Sobel
Department of Applied Physics and Applied Mathematics, Department of Earth and Environmental Sciences, and Lamont-Doherty Earth Observatory, Columbia University, New York, NY


We perform 3-d cloud-resolving simulations of radiative-convective equilibrium (RCE) in a rotating framework, with interactive radiation and surface fluxes and fixed sea surface temperature. We allow a tropical cyclone to develop spontaneously from a homogeneous environment, rather than initializing the circulation with a weak vortex or moist bubble (as is often done in numerical simulations of tropical cyclones). We compare the resulting tropical cyclogenesis to the self-aggregation of convection that occurs in non-rotating RCE simulations. We quantify the feedbacks leading to cyclogenesis using a variance budget equation for the column integrated frozen moist static energy. In the initial development of a broad circulation, feedbacks involving longwave radiation and surface enthalpy fluxes dominate, which is similar to the initial phase of non-rotating self-aggregation. Mechanism denial experiments are also performed to determine the extent to which the radiative feedbacks that are essential to non-rotating self-aggregation are important for tropical cyclogenesis. We find that radiative feedbacks significantly aid the evolution to cyclogenesis, but are not strictly necessary.