乌鲁木齐国际机场一次阵风锋天气成因分析

Analysis of a Gust Front Event Occurred in Urumqi International Airport

利用常规天气资料、跑道自动观测资料(AW0S)、自动气象站资料、卫星云图、多普勒天气雷达等资料,对乌鲁木齐机场发生的一次阵风锋造成的大风和沙暴天气进行分析。结果表明:①阵风锋天气来临时,具有气压陡升、温度骤降、风向变化、风速突增、湿度增加等气象要素的演变特征,跑道两端出现了风向和风速变化的不连续,多个时刻跑道水平风切变强度超过了强度标准值。②阵风锋天气是在500hPa北支槽底分裂短波携带冷空气快速向东入侵渗透下出现的,大风沙暴发生在干线和地面风场辐合区附近,空中"干暖盖"的存在有利于不稳定能量的积累。③对流云团在东移过程中破坏了乌鲁木齐上空的逆温层,促使不稳定能量的释放,呼图壁至乌鲁木齐机场的大风沙暴天气就发生在TBB值梯度的密集带上。④阵风锋在雷达图中表现为强对流回波前方一条弱而窄呈南北向的带状回波,回波强度偏弱,速度场中形成了正负速度交界的辐合带。

On the basis of the analysis of Doppler radar data,combined with conventional weather data,satellite data,AWOS data,and automatic meteorological station data,the gust front event occurred in the Urumqi International Airport is analyzed.The results show that:(1) Meteorological elements changed obviously during the gust front,such as pressure rising,temperature dropping,and wind speed increasing,and the real-time AWOS data show that wind direction and speed at both ends of the runway appeared discontinuous at the same time,and a strong horizontal wind shear occurred on the runway.(2) There was unstable energy accumulated because the moist air was capped by a dry and warm 'lid',and the atmosphere became potentially unstable.The sandstorm occurred near the surface convergence and dry line.(3) The convective clouds destroyed the inversion layer over Urumqi,and released unstable energy during moving eastward to the airport,strong wind and sandstorm from Hutubi to Urumqi occurred where TBB isoline converged with high gradient.(4) The gust front occurred on a narrow band of weak reflectivity and convergence area.