A Numerical Study on the Effects of Orography during the Landfall Process of Typhoon Haitang

The landfall process of typhoon Haitang which affected East China seriously was simulated by using the MM5 model and the track, intensity, precipitation and structure of typhoon were successfully reproduced. Then through the sensitive test, the effects of terrain were analyzed.Results show that the irregular track during the period of typhoon passing through Taiwan and later landfalling at Fujian was in relation to the occurring and developing of orthographic impressed \ndepression. The amount of rainfall was enhanced more than one time and the strength of typhoon was weakened 4 to 5 hPa. It is found that the effect of terrain on the structure of typhoon is limited at low level and is backward in space compared with the one at high level. In addition, the phenomenon that the equivalent temperature in the typhoon’s moving direction inclines to the west on the eye of landfall may be concerned with the terrain.