Resolution Impact on Rapid Intensification and Structure Change of Super Typhoon Hagibis (2019)

Typhoon Hagibis (2019) was a large and intense tropical cyclone that had significant societal impacts in Japan. It went through period of explosive rapid intensification (RI), with an increase maximum wind speed from 60 kt to 160 24 h, immediately followed by secondary eyewall formation (SEF) replacement cycle (ERC). Operational forecasts COAMPS-TC (Coupled Ocean/Atmosphere Mesoscale Prediction System – Tropical Cyclone) failed capture Hagibis' RI, peak intensity, the associated inner-core structural evolution. Four sensitivity experiments, initialized at 1200 UTC 5 Oct. 2019, were conducted study impact horizontal resolution on prediction RI structure. Results indicate storm Category 4 intensity can be simulated finest grid spacing 4-km, but use 1.33-km for facilitates more realistic rate, small inner core accompanying RI. Our experiments simulation SEF/ERC requires very as prerequisite its occurrence; therefore is necessary not sufficient SEF/ERC. The also sensitive outermost grid, which has storm's moisture distribution modulating flow moist air deep tropics into TC. While these results have implications configuration operational models like COAMPS-TC, additional work needed gain systematic understanding physical processes