Impact of the upper-ocean thermal structure on typhoon intensity change in a coupled atmosphere-ocean model

Even though the role of upper-ocean thermal structure (UOTS) on tropical cyclone (TC) intensity has been qualitatively demonstrated, it remains a challenging task to quantify the impact of UOTS on the intensity of an actual TC. In this study, we use a comprehensive full-physics coupled atmosphere-ocean model based on WRF model and PWP ocean model to simulate Typhoon Sinlaku (2008), where unprecedented dropwindsonde data were obtained from four airplanes during T-PARC (THORPEX-Pacific Asian Regional Campaign). In order to have a reasonable initial typhoon structure, a new method of TC initialization based on Ensemble Kalman Filter (EnKF) is applied before conducting the high-resolution coupled model simulation. In addition, some new MPI-related factors are defined to evaluate the contribution of UOTS to typhoon intensity change. For the reason that Sinlaku passed the ocean with varying UOTS features, numerical experiments with different initial temperature profiles of the upper ocean are performed to quantify the impact of ocean on the intensity of Sinlaku. This study would extend our understanding on the impact of UOTS on TC intensity more thoroughly and quantitatively. Besides, it is also hoped that this study would provide valuable physical insights for the field program of ITOP (Internal wave and Typhoon-Ocean interaction Project) in 2010.