Fine resolution simulations of the effect of climate change on tropical cyclones in the South Pacific

Fine-resolution (18 km) regional climate model simulations using the GFDL regional climate model ZETAC are implemented over a South Pacific domain, where the interannual variability of tropical cyclone formation is large. When forced with observed sea surface temperatures and reanalysis boundary conditions, the model is able to give a good simulation of the interannual variation of regions of tropical cyclone formation, with tropical cyclones simulated to form much further east during El Niño years, as observed. An imposed climate-change perturbation is applied to the model, with the resulting simulation indicating that fewer tropical cyclones form in this region in a warmer world. This result appears to be most closely related to increased vertical velocity in the equatorial Pacific, leading to compensating subsidence in the adjacent tropical cyclone formation regions of the South Pacific, thus suppressing tropical cyclone formation.