佛山地区一次局地暴雨过程的重力波特征分析

利用高精度微压计数据,详细分析了2016年11月20–21日佛山地区一次局地暴雨的重力波动态频谱特征,结果表明:重力波激发了此次暴雨,暴雨发生前,重力波呈现出振幅间歇性增大,周期范围不断增宽的过程;其中,暴雨前约4 h出现了重力波最大振幅80–160 Pa,相应的周期范围为140–270min。强雷暴对重力波的作用是积极的,会增大波的振幅,产生中心振幅约80–100 Pa,周期范围210–270 min重力波;尤其是,强雷暴激发了更短周期(≤36 min),振幅约10 Pa的重力波。大振幅重力波提前于暴雨出现,比雷达,卫星识别出强对流早了约4h,这一特征或许对局地强对流预警有指示意义。

Analysis of the characteristics of gravity waves during a local rainstorm event in Foshan,China

A detailed analysis of the dynamic frequency spectrum characteristics of gravity waves(GWs)during a local heavy rainfall event on 20–21 November 2016 in Foshan,China,is presented.The results of this analysis,which was based on high-precision microbarograph data,indicate that GWs played a key role in generating the rainstorm.The GWs experienced two intermittent periods of amplitude enhancement and period widening.The largest amplitudes of the GWs were 80–160 Pa,with a corresponding period range of 140–270 min,which were approximately 4 h ahead of the rainstorm.The severe storms appeared to affect the GWs by augmenting the wave amplitudes with center amplitudes of approximately 80–100 Pa and periods ranging between 210 and 270 min;in particular,the amplitudes increased to approximately 10 Pa for GWs with shorter periods(less than 36 min).The pre-existing large-amplitude GWs may be precursors to severe storms;that is,these GWs occurred approximately 4 h earlier than the time radars and satellites identified convections.Thus,these results indicate that large-amplitude GWs constitute a possible mechanism for severe-storm warning.