0713号台风韦帕路径预报难点分析

Analysis on the Difficulties of Typhoon Wipha(0713) Path Forecast

0713号台风韦帕各家都预报在台湾岛北部海上北折,在120°E以东向偏北方向移动,与台风实际在浙闽交界处登陆后在120°E以西转向北上路径存在较大误差。为认识这种预报偏差的原因,应用各种资料对影响台风韦帕北折的可能原因进行探讨。指出:(1)欧洲气象中心天气形势预报误差较大,西风槽底预报比实况偏南,是本次台风路径转折预报失误的主要原因。(2)欧亚500hPa高度场为两脊一槽形势,西风指数从低指数向高指数演变和副热带高压处周期性加强均不利于台风韦帕在台湾东北部海区折向偏北方向移动。(3)地形的影响造成的趋岸左折和港湾"吸引",以及动力场和热力场的分布均有利于台风韦帕在台湾东北部海区折向偏西方向移动。

There is a big discrepancy of typhoon Wipha （0713） tracks forecasts by various models. The forecasts say that the typhoon Wipha （0713） would turn northward in the sea of northern Taiwan Island towards bias N in the east of 120°E, but the actual path is in the west of 120° E after landing at the coast of Zhejiang and Fujian provinces. To understand the reasons for this discrepancy, every kind of data is applied to study the possible causes. It shows that （1） the errors in the numerical prediction product are the main reasons. （2） One ridge-two troughs situation in the Eurasian 500 hPa height field, the westerly index evolution from low to high and the subtropical high index periodical enhancement are disadvantageous to typhoon Wipha turning bias N in the sea northeast of Taiwan, （3） The terrain impact shore-left changing and Harbor attraction,as well as dynamic field and thermal field distribution led typhoon Wipha to the west in the northeast sea of Taiwan.