The evolution and intensification of Cyclone Pam (2015) and resulting strong winds over the southern Pacific islands

Abstract

Cyclone Pam (2015), a category-5 storm, in the southern Pacific in March 2015 caused severe damages over the islands states in the southern Pacific. Cyclone Pam was originated from an active convective region in the Madden-Julian oscillation (MJO) and evolved from convective clouds into a tropical cyclone. This study numerically investigated the effects of convective processes on the evolution and intensification of Cyclone Pam and the resulting strong winds with the use of the Weather Research and Forecasting (WRF) model through examining sensitivities to cloud microphysics schemes. The numerical simulations successfully reproduced the eastward propagation of the MJO and the aggregation of convective clouds that transformed to a tropical cyclone. It was found that microphysics processes affect the diabatic heating and therefore the evolution of tropical convection into a tropical cyclone. The potential instability for convective development and the actual development of deep cumulus clouds both contribute to the sensitivity of the simulated TC to the choice of the cloud microphysics schemes. Even with such sensitivity, this study successfully reproduced the cyclone track accurately in all the experiments and therefore is able to generate consistent hazard information from the cyclone.

Impacts of Global Warming on Extreme Rainfall of a Slow-Moving Typhoon: A Case Study for Typhoon Talas (2011)

“…This is inappropriate for the impact assessment studies. Takemi (2018) successfully reproduced the track and intensity of a tropical cyclone in the southern Pacific by using the spectral nudging and was able to assess the impact of strong wind hazards at local scales. Therefore, the spectral nudging has to be applied in order to control the typhoon track for assessing local-scale hazards.…”

Benefits of high-resolution downscaling experiments for assessing strong wind hazard at local scales in complex terrain: a case study of Typhoon Songda (2004)

“…In this nudging technique, the maximum wavenumber and the nudging coefficient were chosen as 2 and 0.00028 s −1 , respectively. Note that the spectral nudging plays a critical role in better reproducing the tracks of tropical cyclones (Takemi et al 2016b;Takemi 2018a;Takemi 2019). Furthermore, a typhoon bogus scheme which prescribes a Rankine-type vortex was employed to initialize a typhoon vortex at the initial time of the time integration.…”