一次连续下击暴流天气的成因分析  

Cause Analysis of a Continuous Downburst Weather

作　　者：周后福[1,2] 刁秀广[3] 赵倩[1] 李耀东[4] 夏文梅[5] 

机构地区：[1]安徽省气象科学研究所,安徽合肥230031 [2]安徽省大气科学与卫星遥感重点实验室,安徽合肥230031 [3]山东省气象台,山东济南250031 [4]北京航空气象研究所,北京100085 [5]江苏省气象科学研究所,江苏南京210008

出　　处：《干旱气象》2017年第4期641-648,共8页Journal of Arid Meteorology

基　　金：国家自然科学基金(U1533131;41375120;41575036)资助

摘　　要：基于多普勒雷达、闪电定位、地面观测资料和现场勘察情况,对2016年5月2日皖西南发生的一次连续下击暴流天气的成因进行分析。结果表明:引起2次微下击暴流的风暴为同一风暴单体,且为超级单体,旺盛阶段的雷达回波表现为钩状分布和倾斜结构;下击暴流产生的初始原因是液态或固态降水粒子下降的拖曳作用,中后期则主要源于热力不稳定、对流层中层的动量下传和补偿性气流作用,伴随的水成物与环境之间的负浮力增大是下击暴流发生的重要原因;对流层中层盛行风向造成的动量下传决定了2次微下击暴流的地面风走向;超级单体风暴具有反射率因子核最高和下降速度最快的特点,反射率因子核高度超过6 km,1个体扫间隔下降3 km左右或以上;当6 min降水达4 mm以上时,是发生下击暴流的征兆之一。The cause of a continuous downburst weather occurring in southwestern Anhui Province on 2 May 2016 was analyzed based on Doppler radar data,lightning positioning data,ground observation data and field investigation. The results showed that the storms causing two micro downbursts were actually the same supercell. The radar echoes during the strong stage showed a hooking distribution and declining structure. The downburst was resulted from the dragging force of liquid or solid particles at the initial stage,and derived from the thermal instability,momentum downward in middle level of troposphere and compensatory airflow at the middle and late stage. The negative buoyancy between the water matter and environment increased,which was an important factor causing the downburst,and the direction of prevailing wind in middle level of troposphere causing momentum downward decided the trend direction of ground wind of micro downburst. It＇s worth noting that the supercell had not only the highest reflectivity factor nuclei with 6 km above,but also the fastest falling speed with 3 km around or above within a volume-scanning time interval（6 minutes）. At the same time,the 6-minute accumulative precipitation reached 4 mm and above,which heralded the possible occurrence of downburst.

关 键 词：下击暴流 精细化资料 低空风切变 热力不稳定 动量下传 

分 类 号：P458[天文地球—大气科学及气象学]