“5.10”岷县短时暴雨斜压锋生特征和不稳定条件分析  

Diagnosis of Baroclinic Frontogenesis and Instability Features During “5.10” Short-time Rainstorm Process in Minxian of Gansu Province

作　　者：狄潇泓[1] 许东蓓[1] 肖玮[1] 沙宏娥 谭丹[1] 宋秀玲[1] 

机构地区：[1]兰州中心气象台,甘肃兰州730020

出　　处：《干旱气象》2017年第1期108-115,共8页Journal of Arid Meteorology

基　　金：中国气象局关键技术项目(CMAGJ2014M54);甘肃省气象科研项目(GSMAZd2016-06)共同资助

摘　　要：利用常规气象观测资料、加密自动站雨量和NCEP l°×l°再分析资料,对2012年5月10日甘肃岷县一次短时暴雨并引发山洪的强对流天气成因进行综合分析。结果表明:此次致灾严重的局地性短时暴雨的影响系统斜压性显著,500 h Pa高空槽后较强冷平流和槽前暖湿平流强烈交汇,地面到500 h Pa锋生作用明显。从天气系统基本配置类型看,500 h Pa斜压槽、700 h Pa低涡切变及暖湿气流、地面冷锋是这次强对流过程的影响系统。物理量诊断表明,中低层冷暖平流较强,锋生函数在10日午后明显增强,锋生函数正值区前侧出现强中尺度雨团,雨团朝锋生函数梯度方向移动。此次强对流过程中,大气为条件不稳定,700—300 h Pa温差达-49℃。斜压锋生作用的逐渐增强导致不稳定条件增强,进而导致上升运动发展,是产生本次短时暴雨天气的根本原因。Based on the conventional observation data, automatic stations precipitation and NECP reanalysis data, the causes about a short time rainstorm were analyzed comprehensively which occurred in Minxian of Gansu on 10 May 2012. The results show that the influencing system of the local rainstorm causing severe disaster presented significant baroclinicity. The stronger cold advection behind trough and warm advection in front of trough on 500 hPa converged intensively, and its frontogenesis was obvious from ground to 500 hPa. Instability condition caused by baroclinic frontogenesis was a key factor leading to strong convection. From the point of configuration of the weather system, the baroclinic trough on 500 hPa, vortex shear and warm advection on 700 hPa, and surface cold front were influencing systems of this strong convective process. The diagnosis of physical quantities shows that the frontogenesis function enhanced significantly in the afternoon on 10 May, the mesoscale rain cell appeared in front of the frontogenesis region, and the gradient direction of the frontogenesis function was the moving direction of the mesoscale rain cell. During this strong convection process, the atmospheric stratification was conditional instability, and the temperature difference between 700 and 300 hPa was up to 49℃ . The baroclinic frontogenesis increased gradually during the process, which resulted in enhancement of instability condition and development of ascending motion. It was the root cause of the short - term rainstorm.

关 键 词：短时暴雨 斜压锋生 不稳定条件 

分 类 号：P458.121.1[天文地球—大气科学及气象学]