2013年7月18～19日昆明大暴雨过程的诊断分析

Analysis on a Heavy Rainfall Event in Kunming during 18-19 July 2013

2013年7月18日20：00-19日08：00,云南省昆明市12 h内区域站共出现44站暴雨以上量级的降水,针对这次强降水过程,从高空形势场、物理量场、卫星云图、天气雷达等资料进行综合分析。结果表明,500 h Pa青藏高压和西太平洋副热带高压之间的辐合区是此次强降水的主要影响系统;昆明上空有两股水汽输送,且水汽通量散度对流层中低层辐合中高层辐散,水汽输送条件较好,水汽充沛;昆明上空强降水时段内对流层中低层为正涡度,中高层为负涡度,大气处于不稳定状态,为对流的发展、持续提供了有利的动力条件;昆明上空中尺度对流云团的合并发展,同时在发展过程中位置少动是造成这次大暴雨天气的主要原因之一;此次降水回波属于混合型降水回波,在大片层状云回波中夹杂一些积云强雨团;此次昆明地区的大暴雨天气,与逆风区持续时间密切相关。

There were 44 station rainstorms above the level in Kunming regional station from 20： 00 on July 18 to 08： 00 on July 19,2013. A detailed study on the height fields,physical quantity field,satellite cloud charts and weather radar for this event was conducted. The result showed that： The convergence zone between the Tibetan high and the West Pacific subtropical high is the main effect system at 500 h Pa; There were two water vapor transports over Kunming and moisture flux convergence in the middle-lower troposphere and divergence in the middle-upper troposphere provided the good condition of water vapor transportation and water vapor content; During the relatively strong rainfall period,the vorticity value was positive in the middle-lower troposphere and negative in the middle-upper troposphere,while the atmosphere was in unstable state,it is beneficial for the development and continuation of convection; One of the main reasonsof this heavy rainfall in Kunming is the development of mesoscale convective clouds and the less movement in the process of its development; The precipitation echo belongs to mixed type precipitation echo with some strong cumulonimbus clouds in a large area of stratiform cloud echo; The heavy rain in Kunming area is closely related to the duration of upwind section.