摘要
神农架林区西南坡为局地暴雨灾害多发区。利用常规资料、多普勒雷达资料和区域自动站资料,分析了导致神农架林区西南坡2014年8月6日至7日夜间连续两场短时暴雨过程中MCS发生发展的天气背景及结构特征,并探讨了神农架山区复杂地形构造对西南坡暴雨的增幅作用。结果表明:1)中高层天气系统强迫弱时,副高边缘地面暖低压倒槽及850 h Pa气旋性弯曲区与辐合的发生发展可能是造成这类局地强降水天气的触发系统,地面弱冷空气的入侵有利于降水的维持和加强。2)两次局地暴雨过程均是由中β尺度对流系统影响产生的,降水历时短、强度大,雨区移动呈现局地性,具有明显的中尺度强对流系统特征,分别属前导层状云与尾随层状云中尺度对流系统型。3)第一场暴雨过程以对流降水为主,回波较强;第二场暴雨过程回波质心低且层状云特征比较突出,但维持时间相对较长,降水效率更高。4)神农架西南坡坡度大,海拔高度高,地形的动力抬升和辐合作用促使上升运动加强,地形强迫抬升作用显著不仅对局地对流触发、降水增幅有重要作用,而且会影响中尺度对流系统结构,这可能是神农架林区西南坡暴雨高发的重要原因。
Shennongjia southwest slope is a rainstorm disaster prone area. In this paper, by using the conventional data, Doppler radar data and regional automatic weather station data, the analysis is made on the synoptic background and structure characteristics of the mesoscale convective system （MCS） during continuous two short time rainstorm processes in southwest slope of Shennongjia from August 6th to 7th night 2014, the amplification of Shennongjia mountain complex terrain structure on the southwest slope rainfall is discussed. The results are as follows. 1 ）While the high-level weather system force is weak, ground warm trough on the edge of the subtropical high and 850 hPa cyclone bending area and the convergence developments may be the triggering systems which cause this kind local strong precipitation weather, invasion of weak cold air in the ground is conducive to the maintain and strengthen of rain. 2） The two local rainstorm processes both occurred under the influence of meso-[3 scale convective system, with short rainfall duration, high intensity, little moving and obvious MCS characteristics, belonged in the leading stratiform cloud and trailing stratiform cloud MCS types, respectively . 3）The first rainstorm was based on convective precipitation, with stronger reflectivity, the second rainstorm process was with lower centroid and stratiform cloud more prominent, maintained relatively longer time, and its precipitati- on efficiency was higher. 4）The Shennongjia southwest is a steeply slope with high altitude. The dynamic lifting and convergence effect of terrain can enhance the upward motion. Significant terrain forced lifting effect not only has important roles on the local convection triggering, precipitation increasing, also has effect on the MCS structure, which might be one of the most important reasons for the high occurrence of Shennongjia southwest slope rainstorm.
出处
《气象与环境科学》
2017年第2期100-108,共9页
Meteorological and Environmental Sciences
基金
湖北省重点攻关研究课题"极端强降水临近预警技术研究与应用"(CMAGJ2015M38)资助
