Moist static energy budget analysis of tropical cyclogenesis in climate models

In recent years, climate models have improved such that high-resolution simulations are able to reproduce the climatology of tropical cyclone activity with some fidelity and show some skill in seasonal forecasting. However, biases remain in many models, motivating a better understanding of what factors control the representation of tropical cyclone activity in climate models. We explore the tropical cyclogenesis processes in four high-resolution climate models, including both coupled and uncoupled configurations. Our analysis framework focuses on moisture-convection-radiation feedbacks and was originally developed to study the mechanisms of tropical convective organization in idealized cloud-resolving models. Specifically, a budget for the spatial variance of column integrated moist static energy is applied to quantify the different feedback processes responsible for the amplification of moist static energy associated with the organization of convection and cyclogenesis. We test the hypothesis that radiative feedbacks, particularly feedbacks between longwave radiation and clouds, are important for tropical cyclogenesis. We track the formation and evolution of tropical cyclones in the climate model simulations and apply our analysis both along the individual tracks and composited over many tropical cyclones. The advantage of this approach is that that we can directly compare the genesis processes and, in particular, the role of radiative feedbacks, between the several different climate models and with existing cloud-resolving model simulations. We also use this and other process-based diagnostics to identify model characteristics that are responsible for a good simulation of tropical cyclone activity.