MCC对贵州西部暴雨的影响

MCC's Influence on Torrential Rain in Western Guizhou

利用自动站观测资料、探空资料及NCEP再分析资料,对2010年6月、2012年5月、2014年6月3次贵州西部的暴雨天气过程进行对比分析。结果表明,贵州西部地区出现的MCC,主要发生在副高外围的槽前西南气流中。副高比较强盛,在500~850 h Pa有明显的高压体存在,降水发生后次日没有显著负变温,属于局地锋生。MCC对流云团产生的降雨强度与云团的偏心率和冷云顶面积有很好的对应关系,强降雨时段发生在对流云团发展旺盛的阶段。与周围环境明显的海拔高度差和温度差造成的热力差异,造成了贵州西部地区的中尺度风场辐合线。使得影响贵州的MCC总是在这里触发并发展增强,并带来强降水。3次暴雨过程中贵州中西部的θse等值线都非常密集,上升气流非常明显,中层θse分布呈漏斗状分布,有利于对流性天气发生。3次暴雨过程中,贵州中西部地区都有水汽通量辐合中心存在,充足的水汽输送为MCC发生、发展提供了良好的水汽条件。

＇ 10 · 6＇ , ＇ 12 ·5＇ and＇ 14· 6＇ torrential rain in western Guizhou are analyzed through contrast by u- sing the automatic station observation data, sounding data and NCEP reanalysis data. It demonstrate that MCC in western Guizhou mainly occurs in the southwest flow outside strong subtropical high. All these torrential rain proces- ses have obvious high pressure from 850 hPa to 500hPa, unobvious frontogenesis. The intensity of rainfall produced by MCC is close connected with negative temperature and local the cloud cluster eccentricity and cloud top area, with the strongest intensity occurring when MCC develops greatly. The generation and development of MCC always appear in western Guizhou because of mesoscale convergence line caused by surrounding different alti- tude and thermal difference. These three torrential rain processes both have dense pseudo-equivalent temperature i- soline,visible updraft and the convergence center of moisture flux divergence in central and western Guizhou. The funnel shape of 0se in middle-level is conducive to the happening of convective weather. The sufficient water vapor transportation offers the favorable vapor condition for the generation and development of MCC.