文章摘要
王俊1,刘畅2.一次拖曳型飑线过程雨滴谱演变特征研究[J].海洋气象学报,2019,39(2):43-57
一次拖曳型飑线过程雨滴谱演变特征研究
Study on evolution characteristics of raindrop size distribution during a trailing stratiform squall line
投稿时间:2019-02-02  修订日期:2019-04-10
DOI:10.19513/j.cnki.issn2096-3599.2019.02.005
中文关键词: 飑线  雨滴谱  微物理机制
英文关键词: squall line  raindrop size distribution  microphysical mechanism
基金项目:国家自然科学基金项目(41275044);山东省气象局科研项目(2012sdqx12)
作者单位
王俊1,刘畅2 1.山东省人民政府人工影响天气办公室山东 济南 2500312.山东省气象台山东 济南 250031 
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中文摘要:
      利用Thies激光雨滴谱仪观测资料和CINRAD/SA多普勒雷达观测资料,分析了2017年7月18日一次典型中纬度拖曳型飑线过程不同发展阶段雨滴谱和积分参数的演变特征,主要结果为:1)成熟飑线回波包括对流带、过渡区和拖曳层状云区三部分,对流带前侧不断有对流带生成并合并到主对流带中,使得对流带的前沿具有强的反射率因子,并且有多个雨强大值中心。2)垂直穿过飑线对流带,雨强增加阶段有较少的小粒子(直径小于1 mm)和特大粒子(直径大于5 mm),以及较低的雨滴浓度和反射率因子,而雨强减弱阶段有较多的小粒子和特大粒子,以及较高的雨滴浓度和反射率因子;飑线加强阶段,雨滴谱有较大的峰值直径(0.44 mm)、较多的大(直径大于3 mm)和特大粒子,而飑线减弱阶段,雨滴谱有较小的峰值直径(0.19 mm)、较少的大粒子。3)对流带、过渡区和层状云降水雨滴谱的Gamma谱三参数N0、μ、λ随雨强增大有明显的分层特征,相同雨强时,对流云和过渡区降水的三参数比层状云降水的数值大;而飑线不同发展阶段、不同降水类型的λ-μ关系具有一致性,二次多项式可以很好地拟合λ-μ关系。4)归一化雨滴谱参数NW和D0的分布可以用来区分对流云和层状云降水,并给出了新的分离线方程;另外,飑线在发展和减弱阶段的雨滴谱特征有明显差异,表明飑线演变过程降水形成的微物理机制发生变化,前期冷云过程有重要影响,而后期暖云过程起主导作用。
英文摘要:
      Based on observations of Thies optical disdrometer and CINRAD/SA Doppler weather radar data, the evolution characteristics of the raindrop size distribution and integral parameters at different phases during a typical mid-latitude trailing stratiform squall line on 18 July 2017 are analyzed. The main results are listed as below. 1) The echoes of mature squall line include convective zone, transition zone, and trailing stratiform cloud zone. New convective zones are continuously generated in front of the convective zone and are integrated into the main convective zone, where strong reflectivity factors appear and multiple centers of great rainfall intensity are formed. 2) Crossing the convective zone, the increase/decrease phase of rainfall intensity witnesses fewer/more small particles (Diameter<1 mm) and extra large particles (Diameter>5 mm) as well as lower/higher raindrop concentration and reflectivity factor. During the intensification/weakening phase of the squall line, the raindrop size distribution has relatively large/small peak diameter (0.44 mm)/(0.19 mm) and there are more/fewer large (Diameter>3 mm)and extra large particles. 3) The three parameters of Gamma distribution in the raindrop size distribution of convective zone, transition zone, and stratiform cloud—N0, μ, and λ, have obvious stratified characteristics as rainfall intensity increase. Under the same rainfall intensity, the three parameters of convective cloud and transition zone are larger than those of stratiform cloud; the λ-μ relationship has consistency for different phases of the squall line and different types of precipitation, and a quadratic polynomial can better fit the λ-μrelationship. 4) The distribution of normalized NW and D0 can be utilized to distinguish convective and stratiform cloud precipitation and a new equation of separation line is provided; furthermore, the characteristics of the raindrop size distribution are obviously different in the development and weakening phase of the squall line, which indicates the microphysical mechanism of precipitation has changed during the process. Cold cloud processes have significant influence in the earlier phase, while warm cloud processes play a dominant role in the later phase.
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