盛夏昆明两次致灾大暴雨对比分析

Comparative Analysis of Two Severe Torrential Rains in Kunming in Midsummer

应用常规观测资料、FY-2D、2E卫星观测资料及新一代多普勒雷达回波资料,对"2013.07.19"和"2017.07.20"昆明两次大暴雨对比分析,结果表明:两次过程均出现在全省强降水过程大背景下,强降水时段均出现在盛夏7月的夜间,集中在北部和东部。2013年过程降水量较大,持续时间较长,洪峰水位较高,而2017年过程小时雨强和雷暴次数为最强,城市内涝范围和灾情影响程度较大;两次环流系统均是两高辐合、低涡切变配合暖湿气流共同作用,但2017年有明显的系统前倾,辐合更强;不稳定特征显示,高冷低暖,对流特征指数均体现为对流性不稳定,但2017年CAPE较大、高层冷平流较强,高低空强垂直切变明显,对流层高层干冷空气下侵增强了对流不稳定;滇中昆明均处在MPV 1<0、MPV 2>0的大气对称不稳定条件下强的对称不稳定区,2017年过程由于积聚了大量的较强不稳定能量,强对流天气剧烈但持续时间较短;整层水汽通量散度辐合区分布基本一致,与降水区基本对应;中β尺度对流云团是两次大暴雨的直接影响中尺度系统,但2017年云团强度更强,对流性特征更明显;多普勒雷达回波特征表现,2013年过程为带状混合型降水回波,持续少动,中尺度系统有暖平流、中尺度辐合区持续影响,回波顶高8~10 km,且最大回波强度46 d BZ,而2017年过程为团状、涡旋状对流性降水回波,回波强度强于2013年,小时雨强较大。

By using conventional observation data,FY-2D,2E satellite observation data and the echo data of the new generation Doppler radar,we comparatively analyze two heavy rainstorms in Kunming on July 19,2013 and July 20,2017,and it shows that the two processes occur in the background of the heavy precipitation process in the whole province,and the heavy precipitation periods happen in the midsummer July night.They are concentrated in the north and East.In 2013,the precipitation was large,the duration was long,the flood peak water level was high,while in 2017,the hourly rainfall intensity and thunderstorm frequency were the strongest,and the urban waterlogging area and disaster degree were relatively large.The characteristics of instability show that the convective index is unstable,but in 2017,the CAPE is large,the upper cold advection is strong,the vertical shear is obvious at high and low altitudes,and the invasion of dry cold air in the upper troposphere strengthens the convective instability.Strong symmetric unstable region under unstable conditions,due to the accumulation of a large number of strong unstable energy in 2017,strong convective weather is intense but the duration is short;the distribution of the whole layer of water vapor flux convergence area is basically the same,and corresponds to the precipitation area;meso-beta scale convective cloud cluster is the direct impact of two heavy rains mesoscale system However,in 2017,the intensity of cloud cluster is stronger and the convective characteristics are more obvious;Doppler radar echoes show that the process of 2013 is banded mixed precipitation echoes,with less movement,and the mesoscale system has a warm advection,mesoscale convergence zone,echo peak height is 8-10 km,and the maximum echo intensity is 46 dBZ,compared with 2017.The convective precipitation echo of cluster and vortex is stronger than that of 2013,and the hour rainfall intensity is bigger.