摘要
应用地面、探空、机场自动观测、NCEP再分析资料、多普勒雷达等资料,重点分析了多普勒雷达数据产品,探讨了机场低空风切变形成原因。结果表明:(1)机场低空风切变的主要原因是γ中尺度对流单体底部的紊乱气流造成,此对流单体由北阵风锋与地面中尺度辐合线交汇诱发生成,多个γ中尺度对流单体迅速消亡后产生的下沉气流加强了地面中尺度辐合线,阵风锋和辐合线引起机场低空风切变的产生;(2)风切变过程发生前,皖北地区为不稳定大气层结,925hPa的风场辐合为强对流天气提供触发机制,流经黄海的偏东气流为低层带来充足水汽,皖北强对流风暴的发展和消亡是北阵风锋发生的根本原因;(3)风暴后侧中层干冷空气的侵入阻碍了风暴前沿上升的暖湿气流,促进了风暴内部冷空气的下沉和垂直动量交换,增强了近地层出流强度,两次强反射率因子核高度的迅速下降是北阵风锋发生的直接原因。
Using the data from surface observation,radiosondes,AWSs,Doppler radar and NCEP reanalysis,the mechanism of the wind shear event is analyzed.The results are as followings:(1)The main reason of the low-level wind shear at Hefei Airport was the turbulence at the bottom of the meso-γscale convective cell,which was caused by the convergence of the northern gust front and the mesoscale convergence line.The downdraft produced by the rapid extinction of multiple meso-scale convective cells strengthened the surface mesoscale convergence line.The gust front and mesoscale convergence line caused the low-level wind shear at the airport.(2)The atmospheric stratification was unstable in the northern Anhui before the wind shear occurred.The wind field convergence at 925 hPa provided a triggering mechanism for the strong convective weather,and the easterly flow passing through the Yellow Sea brought enough water vapor to the lower layer.The development and elimination of the severe convective storm in northern Anhui was the fundamental reason for the occurrence of the northern gust front.(3)The mid-level dry and cold air behind the storm hindered the warm air rising,promoted the sinking of the cold air inside the storm and the vertical momentum exchange,which made the outflow intensity of the ground layer enhanced.The two rapid drops of the core height of strong reflectivity factor were the direct cause of the occurrence of the northern gust front.
作者
单乃超
周后福
陈少清
赵倩
Shan Naichao;Zhou Houfu;Chen Shaoqing;Zhao Qian(Meteorological Observatory of Anhui Air Traffic Control Branch,Hefei 230051;Anhui Institute of Meteorological Sciences,Hefei 230031;Anhui Key Lab of Atmospheric Sciences and Satellite Remote Sensing,Hefei 230031)
出处
《气象科技》
2018年第6期1240-1250,共11页
Meteorological Science and Technology
基金
国家自然科学民航联合基金(U1533131)资助
关键词
阵风锋
中尺度辐合线
干冷空气
低空风切变
gust front
mesoscale convergence line
dry and cold air
low-level wind shear
