台湾地形对海棠台风影响的数值模拟研究

Numerical simulation of typhoon Haitang(2005) and the topographic effect of Taiwan island

应用美国国家大气研究中心(NCAR)研发的WRF(Weather Research and Forecasting)气象模式,研究海棠台风(2005)接近并登陆台湾岛的过程中的强度、结构的演变,以及地形强迫作用对台风的影响。对模拟结果的评估表明,在整个海棠台风(2005)模拟实验期间,WRF模式很好地抓住了台风海棠强风,低中心气压的高强度特征。对引起台风降水的中尺度系统的分析表明,一方面台风环流与中央山脉地形共同作用激发出垂直次级环流在降水区域产生强烈的上升运动;另一方面,水平风场源源不断给该地区输送暖湿空气,为对流发展提供充足的水汽。分析结果表明中央山脉地形与台风环流场之间的配置形势对台风降水有着重要的影响。

The Weather Research and Forecasting （WRF） model is used to study the evolution of typhoon Haitang and the topographic effect of Tainwan island. Although the variable track could not be reflected exactly, the model can capture Haitang＇s evolution of intensity and structure, especially its weakening during landfall, as well as precipitation distribution in Taiwan. Analysis of mesoscale system shows that the sub-vertical circulation which is inspired by the interaction of typhoon Haitang circulation with CMR terrain generates strong upward motion in precipitation area. And horizontal wind transports warm and moist air to this area and provides plenty of vapor for supporting convection development. The special correlation between typhoon Haitang circulation and CMR terrain plays an important part in ty- phoon Haitang precipitation.