Vol.18, NO.3, 2007
Turn off MathJax
Article Contents
Article Navigation >  Journal of Applied Meteorological Science  > 2007  >  18(3): 321-329
Xie Jianbiao, Lin Liangxun, Yan Wensheng, et al. Dynamic diagnosis of an infrequent squall line in Guangdong on March 22, 2005. J Appl Meteor Sci, 2007, 18(3): 321-329.
Citation: Xie Jianbiao, Lin Liangxun, Yan Wensheng, et al. Dynamic diagnosis of an infrequent squall line in Guangdong on March 22, 2005. J Appl Meteor Sci, 2007, 18(3): 321-329.
shu

Dynamic Diagnosis of an Infrequent Squall Line in Guangdong on March 22, 2005

  • Guangzhou Central Meteorological Observatory, Guangzhou 510080

  • Received Date: 2005-11-07
  • Rev Recd Date: 2006-11-02
  • Publish Date: 2007-06-30
    Abstract
  • A dynamic diagnosis and meso-scale analysis of an infrequent squall line on March 22, 2005 in Guangdong is made using the routine observations, automatic weather station data, NCEP/NCAR reanalysis data and Doppler radar images. It's found that the squall line occurs under unstable stratification of environmental conditions and unstable physical mechanism, such as the trough at 500 hPa affecting the region where Guangdong borders Guangxi ahead of the trough at 700 hPa, so the acclivitous trough may be the dynamical trigger mechanism of the squall line's occurrence; the intrusion of the dry and cold air down from the upper troposphere affords the thermal instability field; the westerly jet is overlapped with the low southwest jet over the Guangdong and Guangxi, which brings the strong vertical wind shear, and the squall line develops strongly along the exit area of the low level jet after it is formed at the entrance of the upper jet above the low level jet; in the north and south of the squall line there are many new convection cells which keep building and tend to be combined towards the middle of the bow-shaped echo when the squall line grows; the squall line tends to have a dissy mmetrical structure rather than a symmetrical structure when it weakens, and the comma head and tail of the squall line, which cause disasters, are still growing respectively; the echo's channel of weak reflectivity factor at the rear end of the bow-shaped echo, namely the mesosphere-influx mouth of trough, comes forth, which is a sign to the change when the squall line has turned to dissymmetrical structure from symmetrical structure, and the squall line develops to the most powerful stage; in this process it shows some features such as the bow-shaped echo, the V-shaped mouth of trough, MARC and "long convection line" in front of the squall line. The strong inflow center, velocity convergence zone and small vortex velocity feature from the meridional velocity are also found. It is a good sign to identify the change of multi-cell storms that the long convection line of images occurs and develops all along the squall line; diagnostic analysis shows that the physical measures such as the vertical speed, wet static energy and CAPE can reflect effectively where the squall line has been born and where it has moved to.
    • FullText(HTML)
    References(10)

  • Fig. 1  Hourly distribution of severe weather occurrence areas and corresponding locations of squall lines on March 22, 2005

    (thick solid lines denote squall lines, while the thick dashed line indicates convective cloud after the squall line weakened, with the sparse dots, horizontal lines, slash lines, backslash lines, upright lines and dense dots indicating areas of severe weather occurrences at 09:00, 10:00, 11:00, 12:00—13:00, 14:00, 15:00—16:00, respectively; the small squares are stations that observed hailstones.)

    DownLoad: Full-Size Img PowerPoint

    Fig. 2  The composite diagram for synoptic systems at 08:00 on March 22, 2005

    (the thick solid line represents trough at 500 hPa, while the dashed one for trough at 700 hPa; the big arrow indicates dominant cold flow from the north and the small arrow is for jet line at 850 hPa)

    DownLoad: Full-Size Img PowerPoint

    Fig. 3  Isotaches at 200 hPa, locations of jet streams (solid line with arrow for 200 hPa while dashed one for 700 hPa) at (a)20:00 on March 21 and (b)08:00 on March 22, 2005 and strong convective occurence areas only for March 22 (shaded area)

    DownLoad: Full-Size Img PowerPoint

    Fig. 4  Meridional variation of ΔT in upper and lower tropospheres along 110°E at 20:00 on March 21, 2005

    DownLoad: Full-Size Img PowerPoint

    Fig. 5  Observations by the Yangjiang radar at 08:10 on March 22, 2005

    (a) reflectivity factor, (b) velocity, (c) analyzed flow field corresponding Fig. 5b (elevation:1.5°; the distance between two adjacent circles is 50 km; the echo is observed at 150—200 km northwest to the radar station)

    DownLoad: Full-Size Img PowerPoint

    Fig. 6  Observations by the Yangjiang radar at 09:11 on March 22, 2005 reflectivity factor with elevation of 0.5°(a) and 1.5° (b), velocity with elevation of 1.5° (c) (the distance between two adjacent circles is 50 km, the echo is observed at 100-150 km northwest to the radar station)

    DownLoad: Full-Size Img PowerPoint

    Fig. 7  Observations by Guangzhou radar in the direction of 288° on March 22, 2005

    (a) RCS at 10:57, (b) VCS at 11:14 (the center of the strong echo is located in about 15 km from the radar)

    DownLoad: Full-Size Img PowerPoint

    Fig. 8  Echo intensity and mean relative velocity of the storm at 10:57-12:30, observed by the Guangzhou radar on March 22, 2005

    (the red lines with arrows are analyzed streamlines) (a) 10:57 velocity with elevation of 0.5°, (b) 11:32 CR, (c) 12:14 reflectivity factor with elevation of 0.5°, (d) 12:30 reflectivy factor with elevation of 1.5°, (e) 12:14 velocity with elevation of 0.5°, (f) 12:30 velocity with elevation of 1.5°

    DownLoad: Full-Size Img PowerPoint

    Fig. 9  Reflectivity factor observed by the Guangzhou Doppler radar at 11:26 on March 22, 2005

    DownLoad: Full-Size Img PowerPoint

    Fig. 10  Zonal section of vertical velocity along 23°N at 08:00 on March 22, 2005(unit:10 2hPa·s-1)

    DownLoad: Full-Size Img PowerPoint

    Fig. 11  Surface flow field at 09:00 on March 22, 2005

    DownLoad: Full-Size Img PowerPoint

    Fig. 12  Distribution of fields at 20:00 on March 21 (a) and 08:00 on March 22 (b) in 2005(unit:J·kg-1)

    DownLoad: Full-Size Img PowerPoint
  • [1]
    张芳华, 张涛, 周庆亮, 等.2004年7月12日上海飑线天气过程分析.气象, 2005, 31(5):47-51. http://www.cnki.com.cn/Article/CJFDTOTAL-QXXX200505009.htm
    [2]
    罗会邦, 贺海晏, 吴池胜, 等.珠江三角洲局地强风暴.广州:中山大学出版社, 1994:26-39.
    [3]
    朱乾根, 林锦瑞, 寿绍文, 等.天气学原理和方法.北京:气象出版社, 2000:431-434.
    [4]
    俞小鼎, 姚秀萍, 熊廷南, 等.多普勒天气雷达原理与业务应用.北京:气象出版社, 2006:1-314.
    [5]
    Lemon L R. The radar “three body scatter spike”:An operational Large-hail signature. Wea Forecasting, 1998, 13:327-340. doi:  10.1175/1520-0434(1998)013<0327:TRTBSS>2.0.CO;2
    [6]
    漆梁波, 陈永林.一次长江三角洲飑线的综合分析.应用气象学报, 2004:15(2):165-166. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20040221&flag=1
    [7]
    Burgess D W, Lemon L R.Severe Thunderstorm Detection by Radar ∥Radar in Meteorology.Boston:American Meterol Society, 1990.
    [8]
    张培昌, 杜秉玉, 戴铁丕.雷达气象学.北京:气象出版社, 2001.
    [9]
    黄士松, 李真光, 包澄澜, 等.华南前汛期暴雨.广州:广东科技出版社, 1986:123-131.
    [10]
    刘运策, 庄旭东, 李献洲.珠江三角洲地区由海风锋触发形成的强对流天气过程分析.应用气象学报, 2001, 12(4):433-440. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20010458&flag=1
    • Relative Articles
    • Supplements(0)
    • Cited By
  • 加载中
  • -->

Catalog

    Figures(12)

    Get Citation
    PDF
    XML
    Article views (8131) PDF downloads(22145) Cited by()
    • Received : 2005-11-07
    • Accepted : 2006-11-02
    • Published : 2007-06-30
    Journal Online
    Contact

    © 2020 Journal of Applied Meteorological Science   京ICP备15006967号-1

    Supported by Beijing Renhe Information Technology Co. Ltd

    /

    DownLoad:  Full-Size Img  PowerPoint
    Return