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.