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

摘要

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 36min). 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.