Evolution of Typhoon Zeb (1998) in a non-hydrostatic mesoscale model

Due to the complicated terrain and elevated Central Mountain Range (CMR) in Taiwan, a typhoon often experiences great change in its movement and circulation when it moves over Taiwan, . More importantly, the wind and precipitation are also highly influeced by the terrain. In this paper we perform numerical integrations, using a non-hydrostatic mesoscale model (MM5) with 10-km horizontal resolution, to study the evolution of Typhoon Zeb (1997). Several key issues are presented in this study: (1) The merging process of Typhoon Alex with Zeb, and its relation with the intensification of Zeb. (2) The dynamic processes controling the 12h quasi-stationary stay of Zeb over Luzon. (3) The role of CMR on the movement and rainfall distribution associated with Zeb. (4) The role of the upper trough on the recurving of Zeb to the east and northeast of Taiwan.

Results indicate the capability of the model in providing a very accurate track simulation for Zeb. The detailed wind and precipitation pattern around Taiwan is also well simulated. A special comparison of the simulated precipitable water (PW) with that retrieved from surface GPS observations was also made. Work is under way to assimilate the PW data and to evaluate the added-value of the special remote-sensing data on typhoon simulations.