利用Micaps软件系统、多普勒雷达和NCEP 1°×1°再分析等资料, 对2011年6月14日江西北部地区一次超历史极值的短时强降水过程的天气尺度系统和中小尺度系统及其两者关系进行了分析.结果表明, 南支槽移动缓慢、中层干冷空气入侵、强盛的西南急流、高低空急流耦合及地面辐合线维持是造成此次极端降水的主要影响系统.反射率因子表现为低质心、垂直发展旺盛、高效率的强回波连续经过同一地区; 同时, 回波具有明显的后向传播特征和热带降水回波特点; 径向速度表现出锋面过境特征, "牛眼"结构表明了低空西南气流较强.当暖湿急流输送方向与地面辐合线平行时, 孟加拉湾的水汽被低槽前西南气流源源不断地输送到辐合线上空, 使辐合线稳定、维持或发展.干冷气流入侵有利于对流单体的产生; 大风速区和辐合区的发展有利于中小尺度对流单体及其次级垂直环流的维持、发展, 且这些次级环流规则排列, 从而"列车效应"得以维持.有组织的多单体风暴活动、地面静止锋及其附近多条中尺度地面辐合线长时间维持, 是形成"列车效应"的主要原因; 降水回波处于东北—西南向的高能舌北侧移动, 江西东北部特殊的地形作用促使"列车效应"形成和维持.
Using Micaps, Doppler radar data and NCEP reanalysis data, the rainstorm occurred in the north of Jiangxi with the rainfall exceeding the history extreme value on 14 June 2011 was analyzed. Synoptic scale systems、mesoscale systems、microscale systems and their relationship of the rainstorm were also analyzed. It is shown that: The main impact system of this extreme precipitation are the south trough, Mid-level dry air intrusion, the strong low level jet(LLJ), the coupling of high and low level jet stream and the maintenance of the surface convergence line. Due to the low mass center structure、strong vertical development and high efficiency of precipitation strong echo through the same area continuously, the ‘train effect' was occurred in the short-duration rainstorm. Meanwhile, the radar echo which was similar to tropical heavy synoptic scale systems had the characteristic of the backward propagation. There was the characteristic of frontal passage in the speed image, and the speed image with a ‘bull eye' structure shows that there was a low level southwest jet. When the direction of the warm and humid Jet was paralleling to the trend of the ground convergence lines, the ever fount vapor from the Bengal reached the convergence lines along the southwest airflow of the trough, and the convergence lines were stable, maintained and developed. Dry cold air invasion prompted the occurrence of the microscale and mesoscale system in the heavy precipitation. The development of the large wind velocity zone and the convergent region were favorable to the maintenance and development of the microscale and mesoscale convective cells and their sub-vertical circulation, thus the ‘train effect' can be maintained. The activity of organized multi-cell storm, the ground quasi-stationary front and the mesoscale lines which maintained for a long time are the main causes for the formation of ‘train effect'. The precipitation echoes move along with the CAPE center, and the special terrain is also one reason of the ‘train effect'.
[1]期公望. 东亚梅雨锋暴雨研究进展[J]. 地球科学进展, 1994, 9(2): 11-17.
[2]赵玉春, 许晓峰, 崔春光. 中尺度地形对梅雨锋暴雨影响的个例研究[J]. 高原气象, 2012, 31(5): 1268-1282.
[3]王晓芳, 廖移山, 闵爱荣. 影响"05.06.25"长江流域暴雨的西南低涡特征[J]. 高原气象, 2007, 26(1): 197-205.
[4]George Tai-Jen Chen, Chung-Chieh Wang, Sau-Wa Chang. A diagnostic case study of mei-yu frontogenesis and development of wavelike frontal disturbances in the subtropical environment[J]. Mon Wea Rev, 2008, 136: 41-61.
[5]常燕, 王文, 刘丽薇. 平流计算方案对一次江淮梅雨暴雨模拟的影响[J]. 高原气象, 2008, 27(4): 814-822.
[6]陈丽芳, 周春雨, 郦敏杰, 等. 一次梅雨锋结构及锋区强度对锋面结构影响的数值模拟[J]. 高原气象, 2009, 28(4): 924-934.
[7]Takeaki Sampe, Shang Ping Xie. Large-scale dynamics of the meiyu-baiu rainband: Environmental forcing by the westerly Jet[J]. J Climate, 2010, 23: 113-134.
[8]张建海, 沈锦栋, 江丽俐. 2008年浙江梅汛期暴雨的大尺度环流特征及其梅雨锋结构分析[J]. 高原气象, 2009, 28(5): 1075-1084.
[9]柯文华, 俞小鼎, 林伟旺, 等. 一次由"列车效应"造成的致洪暴雨分析研究[J]. 气象, 2012, 38(5): 552-560.
[10]陈明轩, 俞小鼎, 谭晓光, 等. 北京2004年"7·10"突发性对流强降水的雷达回波特征分析[J]. 应用气象学报, 2006, 17(3): 333-345.
[11]应冬梅, 许爱华, 黄祖辉. 江西冰雹、大风和短时强降水的多普勒天气雷达产品的对比分析[J]. 气象, 2007, 33(3): 48-53.
[12]王改利, 刘黎平. 多普勒雷达资料在暴雨临近预报中的应用[J]. 气象, 2005, 31(10): 12-15.
[13]王彦, 吕江津, 周海光, 等. 暴雨的多普勒天气雷达速度辐合风场特征[J]. 气象, 2008, 34(3): 63-68.
[14]何群英, 解以扬, 东高红, 等. 海陆风环流在天津2009年9月26日局地暴雨过程中的作用[J]. 气象, 2011, 37(3): 291-297.
[15]何群英, 东高红, 贾慧珍, 等. 天津一次突发性局地大暴雨中尺度分析[J]. 气象, 2009, 35(7): 16-22.
[16]Maddox R A, Chappell C F, Hoxit L R. Synoptic and mesoscale aspects of flash flood events[J]. Bull Amer Meteor Soc, 1979, 60: 115-123.
[17]孙继松, 何娜, 郭锐, 等. 多单体雷暴的形变与列车效应传播机制[J]. 大气科学, 2013, 37(1): 137-148.
[18]Charles A, Doswell III, Harold E, et al. Flash flood forecasting: An ingredients-based methodology[J]. Mon Wea Rev, 1996, 11: 561-571.
[19]冯晋勤. 列车效应在短时暴雨预报中的研究应用[D]. 南京:南京信息工程大学, 2012: 1-55.
[20]Uccellini L W, Johnson D R. The coupling of upper and lower tropospheric jet streaks and implications for the development of severe convective storms[J]. Mon Wea Rev, 1979, 107(6): 682-703.
[21]Ulanski S L, Garstang M. The role of surface divergence and vorticity in the life cycle of convective rainfall, partⅠ: Observation and analysis[J]. Atmos Sci, 1978, 35(6): 1047-1062.
