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| 上海2004年7月12日飑线系统中尺度分析研究 | |
| 引用本文： | 刘淑媛,孙健,杨引明.上海2004年7月12日飑线系统中尺度分析研究[J].气象学报,2007,65(1):84-93. |
| 作者姓名： | 刘淑媛 孙健 杨引明 |
| 作者单位： | 1. 空军气象中心,北京,100843 2. 中国气象科学研究院,北京,100081 3. 上海中心气象台,上海,200030 |
| 摘 要： | 利用上海地基单多普勒雷达观测资料反演2004年7月12日17—19时(北京时,下同)上海市一次飑线过程的水平风场结构,并用自动站观测的风场资料、卫星云图以及根据雷达回波和时间的连续性和径向速度的特征是否吻合等方面进行综合检验,结果表明反演风场可对飑线进行详尽分析提供可靠的高分辨率资料。在综合多种观测资料的基础上,对这次飑线过程的中尺度系统进行分析,结果表明:(1)这次过程是前倾冷锋前暖区3个主要的β中尺度对流单体和新生的小单体共同作用所致,这3个主要的β中尺度对流单体不是通常个例表现的线状排列,而是冷锋前的两个单体与相对方向的一个单体共同作用,在气团的边缘形成强烈风切变;(2)200多公里长的飑线是由具有独立结构的较小的对流系统串成。在飑线前部存在中尺度的气旋流场,飑线北部末端存在一个气旋流场,南部末端存在一个反气旋流场。而每个单独的弓状回波有自己独立的结构,包括弓状回波后部很强的辐散气流和飑前低压。文中给出了水平风场和回波的结构示意图;(3)在飑线出现以前,低空存在有利于不稳定天气产生的顺时针垂直风切变,而高层则是逆时针垂直风切变。此外,低层入侵的浅薄冷空气为飑线过程提供形成低层不稳定的又一有利因素;(4)飑线中对流单体的移动方向与低层风场方向存在夹角,与锋面云带整体向东移动的趋势也不同,但与1.5 km以上到4.5 km左右的西南气流方向相同,即整体向东北方向移动。这种特征可以对系统短时间移动方向的预报提供帮助。 |
| 关 键 词： | 飑线 弓状回波 中尺度云团 风切变 |
| 收稿时间： | 2005/12/28 0:00:00 |
| 修稿时间： | 2005年12月28 |
STRUCTURAL ANALYSIS OF MESO-SCALE CONVECTIVE SYSTEMS IN THE SQUALL LINE PROCESS ON 12 JULY 2004 IN SHANGHAI |
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| Liu Shuyuan,Sun Jian,Yang Yinming.STRUCTURAL ANALYSIS OF MESO-SCALE CONVECTIVE SYSTEMS IN THE SQUALL LINE PROCESS ON 12 JULY 2004 IN SHANGHAI[J].Acta Meteorologica Sinica,2007,65(1):84-93. | |
| Authors: | Liu Shuyuan Sun Jian Yang Yinming |
| Abstract: | The horizontal wind field structure of the squall-line process during 17:00 to 19:00 BST 12th July 2004 was successfully retrieved from the Doppler velocity data observed by the ground-based Doppler radar in Shanghai.Comprehensive compare was made between the retrieved wind field and the observed data from automatic meteorological observation stations and satellite,and results show good agreement between the single Doppler radar-retrieved and observed wind fields,suggesting that the retrieved horizontal wind field can be used to study the wind field structure of the squall line.An analysis for the meso-scale convective systems (MCSs) in the squall line process was performed using the data observed by meteorological satellite and Doppler radar.The following results are drawn:(1) the squall line process was mainly caused by three-MCSs which were located in the warm sector ahead of a leaning-forward cold front,but not lay on a straight line.The strong wind shear line was located in the interspaces of the three MCSs.(2) The analysis on reflectivity shows that the appearance of a weak narrow-echo-band indicated that the squall line system would strengthen,and it's disappearance that the system would weaken.(3) The squall line 200 km in length comprised several smaller convective systems(bow echoes),and each had an independent structure with a meso-low ahead of and the strong divergent flow rear of the bow.There were a cyclonic flow field ahead of the squall line,a smaller cyclonic circulation in the north end,and a smaller anticyclonic circulation in the south end of the squall line.The sketch map for muti-squall line echoes and winds are given in Fig.6.(4) The squall line moved along with the southwest flow within 1.54.5 km,i.e.in a direction different from the surface wind as well as from the moving direction of the frontal cloud band.5)The analysis on wind profilers shows that the strong clockwise vertical wind shear in lower levels and anticlockwise shear in upper levels before the occurrence of squall line,and the invasion of weak cold air in the low level provided favorable conditions for the genesis and development of the squall line. |
| Keywords: | Squall line Bow echoes MCC Wind shear |
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