2017年3月江苏省一次伴有对流激发的冷空气大风分析

Extraordinary Cold Air Gales Strengthened by Convective Storm Winds in Jiangsu Province in March 2017

利用常规和多普勒雷达观测资料以及逐6 h的FNL再分析资料,对2017年3月1日一次江苏全省大风过程进行了诊断分析,并和2017年2月20日的大风过程进行了简要对比,主要结论为:(1)3月1日冷空气大风的直接原因是大气强斜压性以及高低层辐合辐散的差异,其局部地区的大风还有对流性的雷暴大风叠加的效果。(2)不同于传统的地面气压梯度造成的大风(例如2月20日的大风过程),3月1日过程中地面气压梯度的贡献并不大,其主要是由系统深厚的斜压性所造成(高空冷平流使得位能转化为动能)。(3)春季的不稳定能量比冬季强,在冷空气过程中易被激发出对流。阜宁11级大风(3月1日过程中)就是在大范围的冷空气背景下,不稳定能量先后被锋面和阵风锋激发后所造成的对流性雷暴大风与冷空气大风叠加的结果。

Based on the conventional observation data and the FNL analysis data,a strong wind process occurred on March 1 st,2017 is analyzed and compared with another strong wind process that occurred on February 20,2017.The following conclusions are concluded:(1)The strong wind on March 1 st is a process of momentum transmission downward due to the deep cold advection and the difference of divergence between the upper and lower layers.There are additional convective winds in some areas in this case.(2)Unlike the traditional strong winds caused by strong surface pressure gradient(the February 20 wind process),the contribution of surface pressure gradient is not large in March 1 st process,the main course is the atmospheric baroclinicity,making potential energy converted into kinetic energy.(3)Instability energy in spring can be easily induced in convection during cold air process.In a wide range of cold air background,the strong wind(11 grade)in Funing is the result of superposition of thunderstorm gale stimulated by the ground convergence line(gust front)and cold air gale.