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一次冬季暴雨过程中的锋生和条件对称不稳定分析
引用本文:张芳华,陈涛,杨舒楠,孙军.一次冬季暴雨过程中的锋生和条件对称不稳定分析[J].气象,2014,40(9):1048-1057.
作者姓名:张芳华  陈涛  杨舒楠  孙军
作者单位:国家气象中心,北京,100081
基金项目:国家气象中心2013年预报员专项和公益性行业(气象)科研专项(GYHY201106003)共同资助
摘    要:基于观测资料和NCEP再分析资料,并结合中尺度数值模拟,对2012年1月14—15日我国江南和华南冬季暴雨过程中的锋生与条件对称不稳定(conditional symmetric instablility,CSI)进行诊断分析。结果表明,南支锋区上短波槽东移配合低层冷空气活动,在江南南部到华南地区形成了明显的锋生过程,构成了有利于暴雨过程的天气尺度环流背景;来自孟加拉湾异常充沛的水汽输送形成了冷季暴雨所必须的水汽条件,异常强盛的高空急流人口区右侧的强辐散区也有利于暴雨的形成。在降水过程中锋面附近有多条中尺度雨带活动,锋生函数分析表明,14日夜间广西境内锋生明显增强,在潜热释放的影响下CSI开始发展,相应的锋生次级环流也有所发展,锋前暖区中的上升运动随之增强,导致广西北部形成较强的中尺度降雨带。分析表明,锋生次级环流和CSI实质是锋面次级环流方程(Sawyer-Elissen方程)在不同稳定性条件下的解,锋生强迫环流的性质可由湿位涡作为等价判据进行分析。

关 键 词:冬季暴雨  中尺度雨带  锋生  条件对称不稳定
收稿时间:2013/8/27 0:00:00
修稿时间:2014/5/22 0:00:00

Diagnosis of the Frontogenesis and CSI Features During a Torrential Rainfall Event in Winter
ZHANG Fanghu,CHEN Tao,YANG Shunan and SUN Jun.Diagnosis of the Frontogenesis and CSI Features During a Torrential Rainfall Event in Winter[J].Meteorological Monthly,2014,40(9):1048-1057.
Authors:ZHANG Fanghu  CHEN Tao  YANG Shunan and SUN Jun
Institution:National Meteorological Centre, Beijing 100081;National Meteorological Centre, Beijing 100081;National Meteorological Centre, Beijing 100081;National Meteorological Centre, Beijing 100081
Abstract:Based on the observation, NCEP reanalysis data and the simulation of the mesoscale numerical model (WRF), the frontogenesis and conditional symmetric instability (CSI) during an extremely torrential rainfall event that occurred in southern China in 14-15 January 2012 is diagnosed. The results indicate that both the eastward propagation of the short wave trough along the southern branch trough and the cold air activity in the lower troposphere cause obvious frontogenesis in southern China, which is favorable for the torrential rainfall event in this region. The abnormal abundant water vapor transportation from the Bay of Bengal provides the moisture condition. The torrential rainfall is enhanced by the strong divergence at the right part of the exit of the abnormal strong higher level jet. The mesoscale rainbands form along the surface front. Analyses show the frontogenesis in Guangxi at the night of 14 January strengthens, thus the secondary frontogenesis circulation (SFC) develops. Affected by the latent heat releasing, the CSI is enhanced, leading to an intensifying upward movement in the warm side of the front. Under the circulation pattern, the strong mesoscale rainband occurs in the north part of Guangxi. Theoretic analyses reveal that both the SFC and the CSI are the solutions of the Sawyer Eliassen equation under different stable conditions, and the character of the SFC can be analyzed by the moist potential vorticity.
Keywords:torrential rainfall in winter  mesoscale rainband  frontogenesis  conditional symmetric instability (CSI)
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