低层基本气流对台风的引导作用

根据历史情况,热带气旋的引导气流概念经历了这样的发展和演变1]: 最初的引导概念来自月平均地面气压场,以后随着高层大气观测的发展,出现了愈来愈向高层寻找引导气流的倾向,但不久的一些研究表明,热带气旋的移动与其所处各层大气的基本气流有关,一般与对流层中层500毫巴或700毫巴基本气流最接近.因此,在至今的台风预报业务中,通常着重应用500毫巴或700毫巴形势场分析引导气流的情况.一些台风路径的正压数值预报模式也以中层500毫巴形势场为基础.

THE STEERING EFFECT OF THE LOWER TROPOSPHERIC BASIC CURRENTS ON THE TYPHOON MOVEMENT

Since the fifties vhe middle iropospheric basic currents have been emphasised in the forecasting of typhoon track. It is also shown in some of previous research that the deviation between the typhoon movement and the 500mb basic flow is relatively small I the forecastings of recent year,however, it has been found that the lower-evel basic flows are reratively closer to the actual typhoon tracks than the middle-level ones. Accoroding 260 samples of the typhoon movement forecasting the relationship between 500mb and 850mb geostrophic basic currents and typhoon movement analysed in this page.The result is in general, That the steering effect of the lower-level current on the typhoon movement is not less than that of the middle-level one.Moreover, It is found that the surface basic current took place, an important in several typhoon cases, in which the operational forecasting of the typhoon movement had most large errors at that time. So, the lower tropospheric basic current is worthy to be considered intensively in the forecasting of typhoon movement.