摘要
利用常规气象资料、卫星云图、雷达回波和AWOS资料对2006年5月18日乌鲁木齐地区出现的一次由强降水超级单体造成的局地强风暴进行了研究.结果表明:这次强风暴天气是在前期暴雨结束后冷湿的天气背景下出现的,和以往研究的个例有很大的不同.盖帽逆温的存在,阻止了湿空气向上的输送和扩散,积累了形成强对流天气所需要的能量,同时使大气层结由稳定逐渐变为潜在的不稳定.②从塔克拉玛干大沙漠移出的干暖气团与冷锋后的冷湿气团相交形成的干线触发了积云对流,积云对流在东移的过程中不断加强,最终发展为强降水超级单体.③雷达回波的演变可分为3个阶段:逗点状回波→弓形回波→超级单体,与Fujita描述的弓形回波演变的3个阶段正好相反,超级单体是在逆向演变的弓形回波南端强烈的反气旋式旋转的气流中发展起来的.④中尺度涡旋对(mesovortex couplet)不仅改变了雷达回波的形状,还导致了水汽凝结体(hydrometeors)的重新分布,从而直接影响到超级单体的形成.⑤在强风暴出现前,乌鲁木齐机场跑道东、中、西三端的风向比较乱,风速差异明显;强风暴出现后,跑道三端的风向基本转为一致,变化很小,风速从东到西依次迅速增加,14:11~14:12跑道方向上有强的低空风切变,14:13~14:14在跑道东、西两端同时出现了下击暴流.
Based on the conventional data,satellite image,radar echo and AWOS,a local severe storm caused by heavy precipitation supercell in Urumqi on May 18,2006 is analyzed.The results show that:it occurred shortly after a heavy rain,which was greatly different from the other cases.①The existence of the cappinginversion blocked the upward transportation and diffusion of the moisture,made the accumulation of the energy crucial to the genesis of a severe storm possible,andgradually turned the atmosphere from stable to potential instable.②Triggered by a dry line due to the interaction between the dry and warm air mass moving out the Taklamagan Desert and the cold and moist air mass behind a cold front,the cumulus convection strengthened continuously when it moved eastward,and developed into a heavy precipitation supercell storm to the last.③The evolution of the radar echo could be divided into three stages,comma echo-bow echo-tall echo,opposite to the evolution of the bow echo described by Fujita.The supercell evolved from thecirculation rotating anticyclonically near the southern end of the bow echo.④The mesovortex had not only changed the patterns of the radar echo,but also resulted the redistribution of the hydrometeors related to the formation of the supercell.⑤ Before the storm occurred,the direction and speed of surface wind in different sections of the runway were significantly discrepant.After the storm occurred,the wind directionalmost turned to a same direction,the wind speed increased rapidly from east to west,strong low level wind shear appeared along the runway at 14:11—14:12,downbursts explored near both terminals of the runway at 14:13—14:14.
出处
《云南大学学报（自然科学版）》
CAS
CSCD
北大核心
2009年第S2期438-442,560,共6页
Journal of Yunnan University(Natural Sciences Edition)
基金
新疆气象局业务新技术项目"新疆雷电天气预报预警业务系统研究(YX200901)"资助
