Role of radiative-convective feedbacks in tropical cyclogenesis in rotating radiative-convective equilibrium simulations

“Self-aggregation” is a mode of convective organization found in idealized numerical simulations, in which there is a spontaneous transition from randomly distributed to organized convection despite homogeneous boundary conditions. Previous work has identified the radiative-convective feedbacks that control non-rotating self-aggregation. In this study, the role of these radiative-convective feedbacks in tropical cyclogenesis is investigated in the context of idealized numerical simulations. Specifically, the System for Atmospheric Modeling is used to perform 3-d simulations of radiative-convective equilibrium in a rotating framework, with interactive radiation and surface fluxes and fixed sea surface temperature. Rather than initializing with a broad vortex or saturated column, as is often done in numerical simulations of tropical cyclones, a circulation is allowed to develop spontaneously. The variance budget equation for the vertically integrated frozen moist static energy is used to quantify the feedbacks leading to aggregation, allowing for a direct comparison between the rotating and non-rotating cases. Sensitivity tests in which the degree of interactive radiation is modified 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.