华北地区强飑线的时空分布与发展移动特征

Spatial and Temporal Distribution,Development and Movement Characteristics of Strong Squall Lines in North China

基于2013—2017年华北地区的雷达组合反射率因子数据和雷暴大风观测数据,总共识别了27次强飑线过程,对27次强飑线过程的时空分布及发展移动特征进行了统计分析。结果表明,华北地区强飑线最集中的时间为7月下旬至8月上旬,强飑线最强的时次集中于16:00—22:00;强飑线形成前40 dBz回波起始位置最集中的区域为山西、内蒙古和河北3省交界处附近,强飑线形成位置多在京津冀境内;山西东部到河北西部沿山一带是最长长度达到400 km以上且维持时长超过7 h的强飑线形成位置集中区域;40 dBz回波起始时间为02:00—07:59的强飑线平均形成时长最长,14:00—19:59的强飑线平均形成时长最短;强飑线的最长长度与发展时长及维持时长有较好的对应关系;回波起始时间为14:00—19:59的强飑线形成期移动距离较短但发展期移动距离较长,而回波起始时间为02:00—07:59的强飑线则相反;大多数强飑线发展期的移动速度要快于形成期移动速度。

Based on the radar composite reflectivity factor data and thunderstorm gale observation data in North China from 2013 to 2017,a total of 27 strong squall line processes are identified,and their spatial and temporal distribution,development and movement characteristics are statistically analyzed.The results show that the most concentrated months of the strong squall lines are from late July to early August in North China,and the strongest hours are concentrated from 16:00 to 22:00.Most initial 40 dBz echo locations are near the junction of Shanxi,Inner Mongolia and Hebei.Most strong squall lines are formed in Beijing,Tianjin and Hebei.The area from eastern Shanxi Province to western Hebei Province is the concentrated area of the strong squall lines,with the longest length of more than 400 km and a maintenance duration of more than 7 hours.The strong squall lines with an initial echo time of 02:00-07:59 have the longest average formation duration,while those with an initial echo time of 14:00-19:59 have the shortest average formation duration.There is good correspondence between the longest length of the strong squall lines and their development and maintenance duration.The strong squall lines with an initial echo time of 14:00-19:59 move a short distance in the formation period but a long distance in the development period,while the strong squall lines with an initial echo time of 02:00-07:59 are opposite.Most of the strong squall lines move faster in the development period than in the formation period.