Multi-scale dynamics of tropical cyclone formations in an equilibrium simulation using a global cloud-system resolving model

An equilibrium July simulation was attempted to examine how well a global cloudsystem resolving model (GCRM) simulates the multi-scale dynamics of tropical cyclone (TC) formations. Results for the eastern North Pacific were analyzed to elucidate the capability of the model in capturing the multi-scale dynamics of TC formation in the basin where both the TCs and the large-scale environmental fields were simulated the best. The lifetimes and intensities of the simulated TCs were comparable to the best-track data, which is attributed to the model resolution marginally high enough to represent essential dynamics within a TC inner-core, such as a precipitation-free eye and eye-wall updrafts. Consistent with previous observational studies, some TCs were transformed from synoptic-scale tropical easterly waves that propagated from the North Atlantic. The model also showed meso-scale vortex dynamics related to TC genesis, such as ITCZbreakdown, vortex merger, and Rossby-wave energy dispersion. Thus, the results of the 14-km simulation encourage us to use GCRMs for understanding the multi-scale dynamics of vortices responsible for TC formations, and provide a useful benchmark for the longer-time or higher-resolution GCRM simulations in the future.