湿位涡在广西冰雹大风天气过程诊断分析中的应用

应用湿位涡理论,对2006年4月发生在广西的3次冰雹大风强对流天气过程进行了详细地诊断分析.结果表明:θsc线陡立密集区附近对流稳定度很小,冷空气从高层沿等熵面下滑的过程中绝对涡度增加,导致气旋性涡度的发展加强,为冰雹、大风天气的易发地;强对流天气发生前对流层高层有湿位涡高值中心向下传播,强对流易在正压湿位涡等值线相对密集零线附近和925 hPa上斜压湿位涡负中心附近出现.

Application of Moist Potential Vorticity to Hail and Gale Diagnostic Analysis in Guangxi

According to the moist potential vorticity theory, three hail gale events occurred in Guangxi in April 2006 are diagnosed and analyzed in detail. The results show that the convective stability was very small around the area with dense moist potential temperature isopleths; the absolute vorticity increased during the process of cold air moving downward along the isoentrope surface, leading to the increasing of cyclonic vorticity, which is favorable to the occurrence of hail and gale weather. It is found that there is high MPV (moist potential vorticity) descending downward from the upper troposphere before the hail and gale events; and in the areas with dense barotropic MPV isopleths (around the zero line) and around baroclinic MPV negative centers on the 925 hPa level, heavy convection occurs at a higher probability.