Effect of topography on Tropical cyclone movement

Numerical simulations on a beta plane are preformed using the Weather Research Forecasting (WRF) model to study the effect of Taiwan and Philippines topography on tropical cyclone (TC) movement. Real topography is used in all simulations. In each experiment, different parts of terrain are controlled to be either present or absent in the domain, and some parameters of the TC, such as radius of maximum wind (Rmax), radius of gales wind (R15), maximum tangential wind speed (Vmax), are also varied in different experiments. All experiments are performed without a background flow. Results suggest that TC movement highly depends on the topography and its characteristics. In the experiments with all terrain, there is a good consistency between the TC tracks in the Taiwan and Philippines cases. The tracks of TCs all deviate toward to the right compared with the control (no terrain so that the movement is purely due to the beta effect) when the TCs approach to the land from the southeast of Taiwan and Philippines. When the TC is about to make landfall, it bends towards the high terrain. Higher terrain (aspect ratio of the mountain), larger size and higher intensity of TC would produce a greater bend. Diagnostics of these results and the possible mechanisms will be discussed at the conference.