摘要
2012年盛夏陕西绥德县出现短时强降水,4 h雨量超过100 mm。利用NCEP 1°×1°再分析资料进行诊断分析发现,在陕北东北部对流层中下层有一中α尺度气旋存在,且随高度向东北倾斜,垂直方向上形成次级环流,使强降水区的上升运动加剧。分析地面观测、卫星资料发现,西路冷空气引导干侵入加强层结不稳定性,东路冷空气楔形抬升作用,使得不稳定能量释放;同时,在东西两路干冷空气的夹击作用下,绥德县内形成中气旋,暖湿空气在当地得以聚集上升;2个中β尺度对流云团在东西路风场作用下合并后迅速增强。多普勒雷达资料显示,2个中γ尺度的超级单体回波在绥德先后发展形成列车效应;2个超级单体中的中气旋特征各有不同,是回波结构演变的主要原因。
A short-term heavy rainfall occurred in Suide county of Shannxi province during 14-15 July, 2012 and the four hours＇ rainfall amount has exceeded 100 mm. Diagnostic analysis on the NCEP 1°×1°reanalysis data found that a meso α-scale cyclone exists in the middle and lower troposphere of northeast of northern Shaanxi province, which tilts to northeast with height that make the secondary circu- lation form in the vertical direction and that intensify the upward movement in heavy precipitation region. Based on surface observational data and FY-2E water vapor data analysis, results show that high-altitude westerly airflow steering dry intrusion strengthens the instability of stratification and the wedge-shaped lifting effects of easterly cold air make the instable energy release. The mesocyclone formed in Suide county under the influence of easterly and westerly dry cold air, which makes the moist air gather and rise in the locality; two meso-β scale convective cloud clusters merge and increase rapidly under the influ- ence of east and west wind field. Analysis on Doppler radar data shows that two meso-γ scale HP super- cell echo developed successively in Suide county, whose ＂train effect＂ led to short-time heavy rainfall;mesocyclone characteristics of two supercells are different, which are major causes of echo structure evolution.
作者
王楠
李萍云
井宇
赵强
WANG Nan LI Pingyun JING Yu ZHAO Qiang(Shaanxi Meteorological Observatory, Xi＇an 71 O015, China)
出处
《气象科学》
北大核心
2016年第6期742-751,共10页
Journal of the Meteorological Sciences
基金
公益性行业(气象)科研专项(GYHY201306005)
陕西省自然科学基金项目(2015JM4126)
陕西省气象局重点项目(2015Z-2)
关键词
强降水超级单体
中气旋
干侵入
次级环流
Heavy precipitation supercell
Mesocyclone
Dry intrusion~ Secondary circulation
