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气象:2019,45(8):1135-1148
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“07·06”周口龙卷现场调查和可预警性综合分析
张一平,牛淑贞,郑世林,张宁,王建忠,刘莹莹
(中国气象局河南省农业气象保障与应用技术重点实验室,郑州 450003; 河南省气象台,郑州 450003; 河南省气象局,郑州 450003)
Investigation and Warning Practicability Analysis of the 6 July 2017 Tornado in Zhoukou City
ZHANG Yiping,NIU Shuzhen,ZHENG Shilin,ZHANG Ning,WANG Jianzhong,LIU Yingying
(CMA/Henan Key Laboratory of Agrometeorological Support Applied Technique, Zhengzhou 450003; Henan Meteorological Observatory, Zhengzhou 450003; Henan Meteorological Service, Zhengzhou 450003)
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投稿时间:2018-03-26    修订日期:2019-05-10
中文摘要: 对2017年7月6日周口局地龙卷致灾强对流天气进行现场调查,利用常规高空地面、区域加密自动站、新一代天气雷达以及FY 2G实时分析资料,综合分析了龙卷的环境条件和可预警性。结果表明: (1)此次龙卷灾害主要出现在西华和淮阳两县交界处长约4.5~5 km、宽约100~150 m的地带,具有显著γ中尺度涡旋特征,龙卷强度整体为EF1级,最强达到EF2级。(2)在中纬度低槽东移和副热带高压边缘西南暖湿气流共同影响下,高空分流辐散和低空急流发展的配置为暴雨、局地龙卷提供了有利的天气尺度动力条件,龙卷风暴由强降水冷出流和东部暖湿环境之间形成的辐合线上的气旋性辐合诱发产生,地面自动站温度、露点和能量梯度大值带偏暖湿的正涡度中心附近是龙卷可能发生的区域。(3)08时阜阳探空资料分析大气处于较强的条件不稳定状态,对流有效位能为1712 J·kg-1(14时温度、露点订正后为3182 J·kg-1),K指数为43℃,SWEAT指数为312,SI为-4.5℃;大气可降水量在67 mm左右;抬升凝结高度很低,位于959.2 hPa处;代表低层垂直风切变的0~1 km风矢量差在10 m·s-1或以上。大的热力不稳定和低层垂直风切变及低的抬升凝结高度为小尺度龙卷的发生提供了环境条件。(4)在卫星云图上,龙卷发生在大尺度暖区云带前部,云顶亮温低至-72℃,对流发展非常旺盛。闪电监测龙卷位于闪电密集区东侧。(5)雷达回波图上,龙卷发生在东北—西南向暴雨回波带前沿的块状强回波处。中气旋和龙卷涡旋特征在实时业务中可以作为预警龙卷的可靠线索,根据其持续、移动特点可对局地龙卷提前预警,旋转速度迅速加强、高度下降预示龙卷将影响到地面。以上结论可作为今后黄淮平原监测预警龙卷的参考依据。
Abstract:The severe convective weather in Zhoukou City on 6 July 2017 caused by a tornado was investigated and a general analysis of the circumstance and early warning practicability of tornado was made by using the high-level, surface and AWS data as well as the Doppler weather radar and FY-2G satellite data. The results show that the tornado disaster mainly affected the area with length of 4.5-5 km and width of 100-150 m between Xihua County and Huaiyang County of Henan Province, having considerable meso-γ scale vortex characteristics of the tornado with strength to Grade EF1 and Grade EF2 when strongest. (2) The tornado process was jointly influenced by the mid-latitude trough moving eastward and the warm-moist southwest airflow in the edge of subtropical high. The configuration of upper-level stream divergence and low-level jet offered heavy rain and tornado a favorable synoptically dynamic condition. The tornado was induced by the cyclonic convergent airflows on the convergence line which was between the severe rain cold outflow and the warm-moist airflow in the eastern part. Near the positive vortex center on the big va-lue of surface temperature, dew-point temperature and energy gradient may be where tornado could occur. (3) The Fuyang sounding data at 08:00 BT showed a strong conditional instable air where CAPE was 1712 J·kg-1 (3182 J·kg-1 corrected with surface temperature and dew point temperature at 14:00 BT), K index was 42℃, SWEAT index was 312, SI index was -4.5℃ and the PW was around 65 mm. The LCL was at a very low height of 959.2 hPa, wind vector difference of low-level vertical wind shear at 0-1 km was 10 m·s-1 or above, which offers a profitable circumstance conditions for the tornado. (4) On satellite images, the tornado occurred in the front of warm cloud bands whose TBB was under -72℃ where convective clouds developed vigorously. Lightning monitoring result showed the tornado was on the east side of the dense lightning flashes area. (5) On radar echo maps, the tornado occurred at the massive echo area on the front of northeast-southwest heavy rain echo banks. The occurrence of mesocyclone and its tornado features could give a reliable clue to the warning of tornado in the real-time operation. The enhancing of rotating speed and falling down of the height indicate the tornado would come to the ground surface. In a word, the results above could act as references for tornado monitoring and warning over the Huanghuai Plain.
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基金项目:国家自然科学基金项目(41775044)、中国气象局预报员专项(CMAYBY2018-044)、中国气象局气象预报预测核心业务发展专项[YBGJXM(2018)02-08]、河南省气象局气象科学技术研究项目(KZ201702)和河南省强对流创新团队共同资助
引用文本:
张一平,牛淑贞,郑世林,张宁,王建忠,刘莹莹,2019.“07·06”周口龙卷现场调查和可预警性综合分析[J].气象,45(8):1135-1148.
ZHANG Yiping,NIU Shuzhen,ZHENG Shilin,ZHANG Ning,WANG Jianzhong,LIU Yingying,2019.Investigation and Warning Practicability Analysis of the 6 July 2017 Tornado in Zhoukou City[J].Meteor Mon,45(8):1135-1148.