西风槽与副高相互作用的暴雨过程动热力场结构特征分析  

Analysis of Dynamic and Thermal Field Structure Characteristics on Rainstorm Area in Interaction Process Between Westerly Trough and Subtropical High

作　　者：侯淑梅[1] 郭俊建[1] 张磊[1] 郑怡[1] 孙兴池[1] HOU Shumei Guo Junjian ZHANG Lei ZHENG Yi SUN Xingchi(Shandong Meteorological Observatory, Jinan 250031)

机构地区：[1]山东省气象台,济南250031

出　　处：《气象》2017年第2期151-165,共15页Meteorological Monthly

基　　金：国家自然科学基金项目(41275044);山东省自然科学基金资助项目(ZR2016DM20);山东省气象局课题(2016sdqxz01;2014sdqxm21;2014sdqxm22和2012sdqxz04);环渤海区域科技协同创新基金项目(QYXM201505)共同资助

摘　　要：利用常规气象观测、自动气象站加密观测、NCEP/NCAR(1°×1°,逐6 h)再分析以及FY 2C卫星云图等资料,分析了2007年8月15—18日发生在山东的一次暴雨过程中,西风槽与副热带高压(以下简称副高)相互作用三个阶段的热力、动力场结构特征。结果表明:整个过程先后经历了副高西进切变线缓慢西移、横槽南压副高减弱和横槽转竖副高南撤三个阶段,三个阶段的共同特征是中低层有切变线和θ_(se)锋区;700 hPa有低空急流;产生暴雨的对流云团具有后向传播特征,生命史中多次发生合并。三个阶段的不同点是:(1)副高西进过程中,锋区随高度向北倾斜,坡度小,切变线和θ_(se)锋区均为后倾,为典型的暖锋降水。暴雨区范围大,强度均匀,位于850 hPaθ_(se)锋区与暖脊的交界处的水汽辐合中心附近。饱和区宽广,伸展高度高。低层气旋性辐合、切变线辐合、锋面抬升是触发暴雨的动力机制,低空急流是暴雨增强机制。(2)副高减弱过程中,干冷空气分别从低层和中层侵入θ_(se)暖脊,θ_(se)锋区随高度先向北后向南,呈交错倾斜现象,坡度大,为典型的强对流降水,上升运动最为激烈。暴雨区范围小,强度大,分布不均,位于θ_(se)暖脊垂直方向轴线附近。饱和区狭窄,伸展高度高。锋面抬升运动是触发对流性强降水的主要动力机制,对流层中层干冷空气入侵是强降水的增强机制。(3)副高南撤过程中,θ_(se)锋区随高度向南倾斜,坡度大,呈前倾特征,为典型的高空槽降水。暴雨区狭长分散,强度弱,位于850 hPa切变线上、θ_(se)暖舌靠近锋区一侧。饱和区狭窄,伸展高度低。低层切变线辐合抬升是触发强降水动力机制,中层干侵入是降水增强机制。Based on the conventional observations, AWS, NCEP/NCAR （1°×1°, by 6 h） reanalysis and FY-2C satellite data, this paper investigated the dynamic and thermal field structure characteristics throughout the three interaction stages between westerly trough and subtropical high （SH） in the rainstorm which occurred in Shandong from 15 to 18 August 2007. The results indicated that there are three stages sequentially throughout the whole process. Firstly, SH advanced westward accompanied with the shear line shifting westward at a snail＇s pace; secondly, the transversal trough moved southward with the SH weakening; thirdly, the trough transformed from transversal into upright with SH southward retreating. The three stages share some features in common： There was a shear line and a θse frontal zone in the mid and low levels, and a low level jet （LLJ） at 700 hPa. Besides, the convective cloud cluster had the feature of back-propagating, causing the rainstorm to merge several times in its life. The three stages lies in that： （1） In the first stage, the slope of θse. frontal zone was gentle and shear line and frontal zone backward tilted, so it was typical warm front precipitation. Wi difference of the north tilted th the satur ation region extending broad and upward to 300 hPa, the rainstorm area got extensive and uniform distributed, wavering around the water vapor convergence center in the junction of θse frontal zone and the warm ridge at 850 hPa. So, the low cyclonic convergence, shear line convergence and frontal uplift are the dynamic mechanism of the rainstorm, while the LLJ is the enhancement mechanism. （2） In the second stage, the θse frontal zone was sharp-sloped and intersected-gradient by leaning northward and southward in turn with height, and the cold-dry air invaded into the warm ridge from the low and mid layers respectively, thus creating typical severe convection precipitation and furious upward movement. Also, with the saturation region extending upward to 200 hPa and gettin

关 键 词：副热带高压 结构特征 动力机制 后向传播 饱和区 

分 类 号：P458[天文地球—大气科学及气象学]