东北地区冷涡背景下飑线的统计特征

Statistical Characteristics of Squall Line Under Cold Vortex Background in Northeast China

为进一步研究东北地区冷涡背景下飑线的统计特征,识别出24个东北地区冷涡背景下的飑线过程,并利用动态合成分析等方法,对飑线过程的时空分布、移动特征、形成和消散方式及其与冷涡的关系进行统计研究。结果表明:(1)飑线过程南多北少,与平原-山区交界线的走向一致呈东北-西南向分布。飑线均位于冷涡的南侧,飑线不同时期差异不大。在冷涡发展增强和成熟阶段形成的飑线较多,而且在冷涡的减弱消亡阶段也有多条飑线产生。(2)飑线具有明显的日变化特征,多在午后至凌晨生成,上午最少。70.8%的飑线生命史为3~5 h。最大雷达回波强度在50~60 dBZ。(3)飑线多为从东到东南向直线型移动,中心平均移动速度为14.1 m/s。(4)飑线的形成方式以断续线型(BL)最多,消散方式以倒虚线型(RBL)最多。

In order to further study the statistical characteristics of squall line under the background of cold vortex in Northeast China,24 squall line processes under the background of cold vortex in Northeast China were identified,and the temporal and spatial distribution,movement characteristics,formation and dissipation modes of squall line processes and their relationship with cold vortex were statistically studied by using dynamic synthesis analysis and other methods.The results show that:(1) Squall lines process is more in the South and less in the north,which is consistent with the trend of the boundary between plain and mountain area,and is distributed in Northeast southwest direction.Squall lines are located in the south of the cold vortex,and there is little difference in different periods of squall lines.There are more squall lines formed during the development and maturity stage of the cold vortex,and some of the squall lines are also generate during the weakening and disappearing stage of the cold vortex.(2) Squall lines have obvious diurnal variation characteristics,most of them are formed from afternoon to early morning,and least in the morning.The life history of 70.8% of squall lines is mainly 3 to 5 hours.The maximum radar echo intensity is in the range of 50-60 dBZ.(3)Squall lines mostly moves linearly from east to southeast,and the average moving speed of the center is 14.1 m/s.(4)Squall lines are formed by Broken line(BL) the most,and the dissipation method is Reversed broken line(RBL).