贵州铜仁一次大范围高架雷暴降雹天气过程分析

摘要

利用常规观测、地面加密自动站降水观测、多普勒天气雷达和探空观测资料以及NCEP/NCAR再分析资料,对2016年4月15日夜间发生在贵州省铜仁市多个县的一次大范围冰雹天气过程进行诊断分析,并与当地通常的地面发展雷暴降雹过程进行对比,探寻铜仁市冰雹强对流天气的预报指标.结果表明:(1)"上干下湿"的不稳定层结和较强的垂直风切变是冰雹产生的有利环境条件;(2)地面冷空气侵入,迫使暖湿气流沿"冷垫"爬升,且与850 hPa切变线共同作用在边界层顶触发了强对流天气,冰雹产生在冷垫北侧、850 hPa切变线附近,具有明显的高架雷暴特征;(3)多个对流单体发展成多单体风暴,维持时间较长,强回波柱密实而深厚,回波悬于空中,质心在6 km左右;(4)降雹区VIL集中在30～45 kg·m-2之间,50 dBZ以上的强回波顶高在8 km以上,强回波底高小于3.5 km,VIL和强回波顶高整体小于当地的由地面发展雷暴产生的雹暴.%Based on the conventional observation data,precipitation at automatic weather stations,composite reflectivity factor of Doppler radar in Tongren of Guizhou,sounding data in Huaihua radiosonde station of Hu''nan and NCEP reanalysis data with 1°×1° spatial resolution,a large-range elevated thunderstorm hail weather process at night on 15 April 2016 occurring in Tongren of Guizhou Province was diagnosed and analyzed.Compared with a surface based thunderstorm hail process occurring in Tongren on 2 April 2016,the forecast indexes of hail were explored in Tongren of Guizhou.Results are as follows:(1)The instable stratification with dry air in upper layer and warm air in lower layer and stronger vertical wind shear were beneficial to occurrence of the hail weather process.(2)The intrusion of continuous surface cold and dry air compelled the climbing of warm and humid air along cold pad,and the convergence of shear line on 850 hPa generated the ascending motion at the boundary layer top,which jointly acted on the boundary layer to trigger strong convection.The characteristics of elevated thunderstorm were obvious.The hail occurred in the north of cold pad and near shear line on 850 hPa.(3)Multi-cell storms maintained for a long time in Tongren of Guizhou,the strong echo column was dense and deep,and it hanged in sky with high centroid at 6 km height,which was conducive to the formation and development of hail.(4)During the hailfall of the elevated thunderstorm,VIL in hail area mainly ranged from 30 to 45 kg·m-2,the top and bottom heights of strong echo with more than 50 dBZ were 8 km above and 3.5 km below,respectively.The values of the first two quantities were smaller than those of the surface based thunderstorm hail process on the whole.