带通滤波在华北飑线预报中的应用

本文选择了两种有代表性高空流型的华北飑线个例,应用带通滤波器成功地将实际流场分离成变化缓慢、比较稳定的大尺度环境场和有明显移动变化的中尺度扰动场。一般,在扰动场上出现几个中-α尺度(250-2500km)的扰动系统,其中有一两个扰动系统较深厚,并有规律地移动。它们的水平尺度比飑线系统大,生命史较长并先存在于扰动流场中,飑线就发生在某一扰动的一支较强的气流内。

Application of the bandpass filter for forecasting squall line in North China

The bandpass filter has been utilized to analysis two cases of squall line event in North China. The realistic wind field has been successfully seperated into a slowly variable, more stable macroscale environment field and an obviously movable meso-scale disturbances field. In general, there are several meso-a scale(250-2500km) disturbances emerged into the disturbances field, some of them is deep and moving steadily. The squall line systems occurred in a region of strong air flow associated with one of these disturbances, which is larger and formed earlier and persisted quite longer than the life cycle of the squall lines.