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气象:2016,42(5):567-577
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江苏沿江地区一次强冰雹天气的中尺度特征分析
(1.江苏省气象科学研究所,南京 210009;2.江苏省气候中心,南京 210009)
Mesoscale Characteristics of a Severe Hail Event over the Area Along Yangtze River in Jiangsu
(1.Jiangsu Institute of Meteorological Sciences, Nanjing 210009;2.Jiangsu Climate Centre, Nanjing 210009)
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投稿时间:2015-07-24    修订日期:2016-01-18
中文摘要: 利用常规气象资料、卫星、多普勒天气雷达、风廓线雷达等资料,对发生在江苏沿江地区一次强冰雹天气形势背景、环境热动力条件、强冰雹发生前地区环境场变化、超级单体雷达回波中尺度特征等进行了详细分析。结果表明:(1)在东北冷涡槽后干冷气流影响下,中高层干冷、低层暖湿的不稳定层结,高低空急流以及地面辐合系统的配置为此次强对流天气的产生提供了有利热动力条件;高CAPE值、逆温层、低层适当水汽条件及较强的深层垂直风切变有利于强冰雹天气的发生。(2)利用多普勒天气雷达、风廓线仪数据反演垂直分布的物理量场(平均散度、平均垂直速度、相对风暴螺旋度、垂直风切变)能够反映本站上空环境场的快速变化情况:强对流系统移入本站前雷达站上空逐渐调整为低层辐合、中高层辐散的风场配置结构,螺旋度和垂直风切变数值逐渐增加,表明环境场有利于强对流系统的维持发展。(3) 强降雹超级单体除具有三体散射现象、入流缺口等雷达回波中尺度特征外,持久深厚的中气旋存在造成了显著的有界弱回波区和高悬垂强回波区。应用双多普勒雷达风场反演技术揭示了超级单体内部环流结构:低层气旋性旋转,中层旋转加强,高层风场辐散。超级单体内部涡旋特征的出现和维持有利于支撑空中大冰雹的增长。
Abstract:A severe hail event occurred along Yangtze River in Jiangsu on 28 April 2015. Based on the data of AWS observation, geostationary satellite, Doppler weather radar and wind profiler radar, this paper analyzes the characteristics of the synoptic weather pattern, thermodynamic conditions, changes of ambient wind field before hailstorm, and structure of the supercell storms. The results show that first, with Northeast vortex and the dry and cold airflow at the back of vortex trough, unstable stratification is formed by the dry and cold airflow in the mid high level and the warm and humid airflow in the low level, the configuration of the high and low level jet and the surface convergence system provide a favorable thermal condition. The high CAPE values, inversion layer, favorable water vapor in the low layer and the strong deep vertical wind shear are conducive to the occurrence of severe hail weather. Second, the vertical distribution of physical quantity fields, such as average divergence, the mean vertical velocity, relative storm helicity, vertical wind shear, retrieved by the Doppler weather radar and the wind profiler radar data can reflect the rapid change of the ambient field, which is gradually adjusted into the pattern of low level convergence and upper level divergence, and the values of the helicity and vertical wind shear are gradually increased before the convective system moves into the area of the radar station. Such situation indicates that the ambient field is suitable for the maintenance and development of the severe convective system. Third, besides the TBSS phenomena and the front inflow notch found in the radar echo of the severe hail supercell, the prominent bounded weak echo area and suspended high strong echo area are made by the persistent deep mesocyclone. The inner loop structure of the supercell is revealed by the application of the dual Doppler radar wind field retrieval technique. The ambient field is cyclonic rotation in the low level while rotation in the middle level is strengthened and the wind field in the high level is diverged. The emergence and maintenance of the vortex in the supercell contribute to the growth of large hail in the air.
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基金项目:北极阁基金项目(BJG201509)、国家自然科学基金项目(41475042、41575036)、公益性行业(气象)科研专项(GYHY201406006)、江苏省气象科研重点项目(KZ201407)和江苏省科技支撑计划 社会发展项目(BE2013730)共同资助
引用文本:
徐芬,郑媛媛,肖卉,慕熙昱,2016.江苏沿江地区一次强冰雹天气的中尺度特征分析[J].气象,42(5):567-577.
XU Fen,ZHENG Yuanyuan,MU Xiyu,XIAO Hui,2016.Mesoscale Characteristics of a Severe Hail Event over the Area Along Yangtze River in Jiangsu[J].Meteor Mon,42(5):567-577.