渭河流域一次致洪暴雨过程的中尺度滤波分析  

Mesoscale filter analysis on one flash flood of Weihe river valley

作　　者：段昌辉[1] 武麦凤[1] 

机构地区：[1]渭南市气象局,陕西渭南714000

出　　处：《气象科学》2012年第1期110-117,共8页Journal of the Meteorological Sciences

基　　金：中国气象局预报员专项(CMATG2008Y10)

摘　　要：利用常规高空观测资料和NCEP/NCAR 1°×1°的再分析资料以及25点低通滤波技术,对2003年8月28—29日发生在渭河流域的一次致洪暴雨进行了中尺度分析和探讨,分析出中尺度环流演变特征,总结了渭河流域致洪暴雨的概念模型,认为这次暴雨过程中在以西南气流为主的平均气流场上隐藏着尺度较中尺度平均流场小得多的涡旋,其移动方向和发展程度决定了强降水落区及其强度;高空西风风速脉动与低层南风风速脉动耦合形成了中尺度次级环流圈,其上升支为强降水提供了足够的动力抬升机制;而850 hPa低空急流、700 hPa中尺度低涡、南风脉动以及高空西风风速脉动等条件的合理配置是中尺度次级环流形成的必备因素;地面中尺度辐合线是本次暴雨的触发机制。Mesoscale filter analysis for one flash flood process in Weihe river valley is performed with the route sounding data and NCEP 1°×1°reanalysis data,based on the 25-point low-pass filtering technique,so that a model for flash flood of Weihe river valley was set up by using of meso-scale circulation evolution characteristics.The results show that vortexes with scale less than medium were hidden in the average southwest stream.Its movement direction and development level could determine the area and the intensity of heavy precipitation.The coupling of westerly fluctuation at high level with south fluctuation at low level resulted in a meso-scale secondary circulation loop,its rising branch provided sufficient impetus for the heavy rainfall.And the reasonable allocation of the low level jet,mesoscale circulation at 700 hPa and west fluctuation at high level was the necessery factor for the mesoscale secondary circulation loop.The surface mesoscale convergence line was the trigger mechanism for this flash flood.

关 键 词：低通滤波 中尺度涡旋 中尺度次级环流 低空急流 地面中尺度辐合线 

分 类 号：P458.121[天文地球—大气科学及气象学]