2010年后汛期一次东风波雷雨大风天气分析

Analysis on an Easterly Wave Thunderstorm and Gale Weather in Latter Flood Season of 2010

[目的]分析2010年后汛期一次东风波雷雨大风天气。[方法]利用常规观测资料、自动站资料、NCEP 1°×1°再分析资料和多普勒雷达反射率、径向速度资料,对2010年8月4～5日东风波雷雨大风天气过程进行了分析,研究了雷雨大风发生的环流形势、东风波风场和动力热力结构、多普勒雷达回波特征等。[结果]此次雷雨大风天气发生在深厚东风波槽前的东北风区域。发生时,副高位置偏北(脊线35°N),北支槽的东移迫使副高分裂成东西2环。东环副高西伸、鞍形场环流有利东风波生成发展。随着东风波发展西移,在其槽前影响区域,高空东风分量下传,使低空东北风显著加大,出现雷雨大风天气。雷雨大风发生的区域,中低层气流气旋式辐合,近地层反气旋式辐散,下沉运动明显;并具有中高层趋干冷、低层趋暖湿的热力结构。4日,超级单体风暴处在发展阶段,具有明显中气旋和钩状回波特征(中小尺度特征)。5日,广东中西部出现飑线和大风区、逆风区特征。中气旋、钩状回波和飑线、大风区、逆风区多普勒特征对雷雨大风短临预报具有指示意义。[结论]该研究揭示了一些对当地预报此类东风波雷雨大风有意义的信息。

[Objective] The research aimed to analyze an easterly wave thunderstorm and gale weather in latter flood season of 2010.[Method] Based on conventional observation data,data of automatic station,NCEP 1°×1° reanalysis data,Doppler radar reflectivity and radial velocity data,the easterly wave thunderstorm and gale weather process which happened during 4-5 August,2010 was analyzed.The circulation situation,wind field and dynamic thermal structures of easterly wave,echo characteristics of Doppler radar when thunderstorm and gale happened were studied.[Result] The thunderstorm and gale weather happened in northeaster zone in front of deep easterly wave trough.When the thunderstorm and gale weather happened,the position of subtropical high was by north（the ridge line was at 35° N）.The eastward movement of north branch of trough compelled subtropical high splitting into east and west circulation.The westward extension of east subtropical high and saddle-type filed circulation were favorable for generation and development of easterly wave.As the development and westward movement of easterly wave,in the influence zone in front of trough,the upper easterly component transmitted downward.Then,the low-level northeaster obviously strengthened,and the thunderstorm and gale weather appeared.In the zone where the thunderstorm and gale happened,the airflow at middle and low layers had cyclonic convergence,and had anti-cyclonic divergence near ground layer.The subsidence movement was obvious.Moreover,the thermal structure that it tended to be dry and cold at middle and high layers,warm and wet at low layer existed.The supercell storm was at developed stage on 4th.It had obvious meso-cyclone and hooked echo characteristics（meso-and small-scale characteristics）.The characteristics of squall line,gale region and adverse wind region appeared in central west Guangdong on 5th.Doppler characteristics of meso-cyclone,hooked echo,squall line,gale region and adverse wind region had indication significance for the short-imminent forecast of thunderstorm and gale.[Conclusion] The research revealed some information which had significance for forecasting local easterly wave thunderstorm and gale weather.