摘要
利用地基微波辐射计、风廓线雷达和雨滴谱仪等观测资料,对2015年4月28日发生在南京的一次冰雹天气进行了分析,探讨新型探测资料在冰雹监测预警中的应用。结果表明:(1)华北冷涡后部冷空气南下,与低层暖湿气流交汇,是产生这次冰雹的天气背景;高空冷平流叠加在低层暖湿气流之上,使得对流层中低层形成不稳定层结;地面辐合中心及辐合线是降雹的触发机制。(2)微波辐射计监测显示,降雹期间冰雹云中上升气流将底层空气的感热和潜热向上输送,导致2 km以上大气有明显升温,由于低层水汽聚集及冰雹在近地层融化造成降雹时近地层相对湿度、水汽密度增大。冰雹发生在云液态水含量快速增长的波峰上,对冰雹的发生具有较好指示意义。(3)对比南京3站风廓线雷达资料表明各站上空环境风场存在一定差异,六合地区降雹前6 km高度高空急流有利于六合上空形成有利的辐散形势,降雹时0~6 km存在较深厚的垂直风切变,配合地面中尺度低压,降雹最为强烈;南京站降雹时,对流层中下层有一槽过境,而高淳地区冰雹由近地面垂直风切变激发。(4)六合站、高淳站雨滴谱仪分析表明不同降水相态对应的滴谱特征有差异,两站雨滴谱型分别呈指数型、多峰型分布。高淳站雨滴谱仪监测到直径达到15 mm的冰雹粒子,六合站冰雹直径最大为5 mm。两站速度谱大致为单峰型,在较强降水时刻,粒子下落峰值速度在3~4 m·^(-1)。(5)影响六合的超级单体存在钩状回波、回波悬垂、三体散射等雷达回波中尺度特征,地面中尺度低压系统、中低层的中气旋及高层的辐散环流配置造成了雹云中维持较强的旋转上升气流,有利于出现大冰雹。
The hailstorm process in Nanjing on 28 April 2015 is analyzed by using microwave radiometer, wind-profiling radar, laser precipitation particle spectrometer and other automatic observation data. The results show that. (1) The combination of cold air associated with cold vortex over North China stretching towards the south and lower-level moisture air was found to be the circulation background of the severe hailstorm in Nanjing. The transportation of upper-level cold advection and lower-level warm advection strengthened the formation of the extreme unstable atmosphere stratification. The lasting of surface medi- um-scale convergence center and convergence line played the triggering role in the hail weather. (2) In the hail clouds, strong updraft transport of low-level air sensible heat and latent heat led to significant increase of ambient temperature above 2 km altitude observed by microwave radiometer. When the hailstorm was in progress, continuous convergence of low-level moisture air and the hail fell into the melting area, causing an increase in low-level relative humidity and vapor density. Integrated liquid water (ILW) showed doublepeak structure. When the hailstorm process was initiated, ILW increased rapidly and reached maximum, which indicates the beginning of severe convective weather. (3) Comparing wind-profile radar products in 3 sta- tions, various vertical wind fields were observed in different regions. The hailstorm process in Luhe was closely related to the deep vertical wind shear at 0--6 km and the upper-level jet stream, incorporating with the mesoscale cyclone on the ground and middle-level mesocyclone, which made the hail process very intensive. The east movement of trough in lower troposphere was observed when Nanjing was hailing, while the vertical wind shear at lower-level forced continuous hail shooting at Gaochun. The conclusion makes a further understanding of environment condition about vertical structure during this heavy hail- storm event. (4) The micro-structure characteristics of the precipitation at Luhe and Gaochun is discussed by using the laser precipitation spectrometers. The different droplet spectra characteristics corresponding with different precipitation types, the raindrop size distribution pattern in two stations basically showed the form of exponential distribution and multi-peak structure respectively. Gaochun monitored hail with maximum diameter of 15 mm and Luhe was 5 ram. The raindrop velocity distribution both showed single- peak type, and the terminal speed of particles during the severe raining period was between 2 and 5 m · s-1. (5) The severe hail supercell storm at Luhe showed typical features of hook-shaped echo, suspended high strong echo area and TBSS.
作者
李聪
姜有山
姜迪
李力
张蓬勃
LI Cong JIANG Youshan JIANG Di LI Li ZHANG Pengbo(NanJing Meteorological Bureau, Nanjing 210019)
出处
《气象》
CSCD
北大核心
2017年第9期1084-1094,共11页
Meteorological Monthly
基金
江苏省气象局预报员专项(JSYBY201411)
华东区域气象科技协同创新基金合作项目(QYHZ201604)共同资助
关键词
冰雹
微波辐射计
风廓线雷达
激光雨滴谱仪
hailstorm, microwave radiometer, wind-profiling radar, laser precipitation particle spectrometer