西风槽影响下豫西北两类强对流天气流型和物理量特征分析  

Flow Pattern and Physical Characteristics Analysis of Two Categories of Severe Convective Weather Influced by Westerly Trough in Northwest Henan

作　　者：司福意 赵海清 李社宗[2] Si Fuyi;Zhao Haiqing;Li Shezong(Jiaozuo Meteorological Office,Jiaozuo 454003,China;Zhengzhou Meteorological Office,Zhengzhou 450005,China)

机构地区：[1]焦作市气象局,河南焦作454003 [2]郑州市气象局,郑州450005

出　　处：《气象与环境科学》2018年第3期57-63,共7页Meteorological and Environmental Sciences

基　　金：国家重点基础研究发展规划项目(2012CB955204);国家自然科学基金项目(41275095);焦作市科技项目"焦作旅游气象监测预报服务平台"(2004-17)资助

摘　　要：西风槽是诱发豫西北雷雨大风和暴雨等强对流天气的一种重要的天气系统。利用常规高空、地面观测和探空资料,对2001-2015年6-9月受西风槽影响在豫西北发生的区域性强对流天气过程的分析发现,由于近地面暖湿空气势力和侵入冷空气的强弱不同,致使天气系统配置差异显著。根据不同天气系统配置,将由西风槽入侵引起的强对流天气过程分为斜压锋生类和低层暖平流强迫抬升类两种。斜压锋生类的显著特征是配合高空槽的移近,影响系统在700 h Pa上有明显的冷槽,在近地面层有明显的锋生和锋面移近,锋面逼近使抬升运动增强是强对流天气启动的重要因素;低层暖平流强迫类的影响系统在700 h Pa上有位势高度槽而无冷槽,槽的南段紧贴或者落后于500 h Pa槽线,呈前倾结构,强的热力不稳定和深层垂直风切变所形成的动力不稳定是引发这类强对流天气的主要因素,地面辐合线、干线触发了强对流天气。二者在物理量场分布上也有着显著的异同:相同之处在于两类强对流天气均有较强的位势不稳定且积累了大量的不稳定能量,两类强对流过程的0℃层均接近或超过5km。不同之处主要有以下几点:1)斜压锋生类中低层湿度更大,湿层更厚。2)低层暖平流强迫类850-500 h Pa的温差均值为27. 7℃,大于斜压锋生类的温差。3)斜压锋生类K指数均值达39. 6℃,低层暖平流强迫类K指数均值为28. 7℃,二者差值高达10. 9℃,而其抬升凝结高度却明显偏低。4)斜压锋生类中低层的垂直风切变较大,而低层暖平流强迫类的对流层高层与近地面间的垂直风切变较大。Westerly trough is an important weather system to induce severe weather like thunderstorm gale,heavy rainstorm,etc.in northwest Henan.By using conventional high and surface observation data,sounding data,the severe convective weather cases from June to September during 20012015,influenced by the westerly trough in northwest Henan were analyzed.The results showed that there were significant differences in the synoptic system configuration as the intensity of warm air forces near ground were different with the intensity of cold air intrusion.According to the different synoptic system configuration,the severe weather processes were divided into two types,one was baroclinic frontogenesis,the other one was low level warm advection forced uplift.The typical characteristics of baroclinic frontogenesis were that its geopotential height was accompanied by a clear temperature trough at 700 hPa.There were obvious frontogenetic and cold front approaching near the ground,and the uplift enhancement due to front approaching was an important factor to the start up of strong convective weather.For the latter,there was a geopotential height trough at 700 hPa,but no temperature trough,and its southern section was a forward structure,near or behind the 500 hPa trough.The dynamic instability caused by strong thermal instability and deep vertical wind shear was the main factor to induce severe convective weather,which was triggered by the convergence line and dry line.There were significant similarities and differences in the distribution of physical quantity field.They both occurred in a strong potential unstable environment,and accumulated a large amount of unstable energy,while their 0 ℃ layer were close to or above 5 km.The differences were as follows.1）The humidity was bigger and wet layer was thicker in baroclinic frontogenesis.2）The average temperature difference between 850 hPa and 500 hPa was 27.7 ℃ in low level warm advection forced uplift,which was bigger than in baroclinic frontogenesis.3）The mean K index in baro

关 键 词：强对流 西风槽 天气流型配置 物理量特征 

分 类 号：P458.1[天文地球—大气科学及气象学]