Moist Thermodynamics of Tropical Cyclone Formation and Intensification in High-Resolution Climate Models

The objective of this work is to achieve a better understanding of what factors control the representation of tropical cyclone activity in climate models. We explore tropical cyclogenesis and intensification processes in six high-resolution climate models from NOAA/GFDL, NCAR, and NASA. Our analysis framework focuses on how convection, moisture, clouds and related processes are coupled and employs process-oriented diagnostics including budgets of column moist static energy and the spatial variance of column moist static energy. The latter allows us to quantify the different feedback processes responsible for the amplification of moist static energy anomalies associated with the organization of convection and cyclogenesis, including surface flux feedbacks and cloud-radiative feedbacks. We track the formation and evolution of tropical cyclones in the climate model simulations and apply our analysis along the individual tracks and composited over many tropical cyclones. We use two methods of compositing: a composite over all TC track points in a given intensity range, and a composite relative to the time of lifetime maximum intensity for each storm (at the same stage in the TC life cycle). We find that differences in the sensitivity of convection to moisture and strength of the surface flux – wind speed feedback explain differences in TC intensity between the models.