A numerical experiment for the effect of Taiwan island terrain on super typhoon Fanapi (1011)

Numerical simulations and sensitivity experiments for the effect of Taiwan island terrain on track, precipitation and structure of super typhoon Fanapi (1011) were performed with the WRF-ARW 3.2.1 model. The results indicate that owing to effect of the topographic low pressure at windward slope, the typhoon moved southward and had a motion in the counter-clockwise direction before it landed on the Taiwan island. The topographic low pressure at leeward slope and the bow-shaped positive vorticity zone in northwest side of the typhoon make it move in a V-type track when it was in the Taiwan Straits. The obstruct by Taiwan island terrain makes the water vapor convergence and the positive vorticity decreased in northwest side of the typhoon, but increased in east and south side of the typhoon. The typhoon presents an asymmetric structure of weak in northwest and strong in southeast in its intensity and an inhomogeneous distribute of precipitation. The Terrain effects of mountains in the central Taiwan regions on typhoon flow field in the low-level leads to to increase of precipitation and an asymmetric precipitation distribution being strong in south and east and weak in northwest Taiwan regions.