低层流场短时波动和中尺度扰动自激作用

Short-time fluctuation in flow field of lower levels and trigger action of mesoscale disturbance

本文利用稠密地面自记资料分析了台风暴雨过程中地面强风及其波动与下游暴雨雨团发生、移动和雨强振荡的相对应事实,计算了涡(散)度方程中非线性项量值,讨论了地面风速分布不均匀引起散度局地变化和涡(散)度场相互作用对暴雨中尺度系统的激发过程。指出注意地面风场特征及其变化,将有助于捕捉暴雨中尺度系统和暴雨的短时预报。

In this paper,the selfrecording data over denser surface are used to analyse strong surface wind and its fluctuation in the process of typhoon-caused severe rain corresponding with the genesis and movement of the rain clusters in downstream as well as oscillation of rain intensity.The values of nonlinear terms in the divergence and vorticity equation are computed.Local variation of the divergence caused by the inhomogene-ous distribution of the surface wind velocity and the effects of interaction between vorticity field and divergence field on trigger process of mesoscale system of severe rain are discussed.Finally, it is also pointed out that it is helpful to be knowledyed of the feature and variation of surface wind field in order to catch of mesoscale system of severe rain and to make the short-time forecast of it.