[A-AS04] Advances in Tropical Cyclone Research: Past, Present, and Future

[AAS04-P03] A Revised Tropical Cyclone Genesis Potential Index for Tropical Cyclone Projection in the Western North Pacific

*Li-Peng Hsiao¹ (1.ACADEMIA SINICA)

Keywords: tropical cyclone activity, genesis potential index, global warming

The study utilized the results of high-resolution models, which can explicitly simulate tropical cyclone (TC), and treated the simulated TC genesis as the “truth” to evaluate two TC genesis potential indices in reflecting the projected TC changes in the western North Pacific (WNP) under warming scenario. Both a widely-used TC genesis potential index (χGPI) and a revised index (χMqGPI) well represented the seasonal variation of TC genesis frequency (TCGF) and its spatial distribution in both historical simulation and observation data. The χGPI projected a significant increase in TCGF in response to the future warmer ocean surface, in contrast to the significant reduction in model projection. This mismatch was attributable to the dominant control of SST on the index, despite that higher SST in the WNP was often caused by more stable atmospheric conditions and therefore fewer TC occurrences. By contrast, the χMqGPI that considers gross moisture condensation properly projected a TCGF decrease, although the degree of reduction was smaller than that derived directly from TC detection scheme. Overall, the χMqGPI more accurately reflected the decreasing trend of TCGF in the warming simulations than the χGPI .