大理机场一次晴空大风天气诊断分析

Diagnosis Analysis of a Clear Sky Windy Weather in Dali Airport

利用常规气象资料、NCEP2.5°×2.5°资料和风廓线雷达资料,分析了2015年2月27日晴空大风天气过程。结果发现:大理机场上空位于高空西风急流轴附近,虽然高空冷平流较弱,但是动量下传是造成大风的主要因子。当高空至机场近地面均为下沉运动时,下沉气流携带高空的动量下传,造成大理机场出现大风天气。相反,当近地面至700 h Pa为上升运动时,上升气流会阻碍高空动量向下传递,机场大风结束。风廓线雷达资料分析也表明动量下传是27日大风的主要动力因子,当高空到地面均为下沉运动时,大于3 m/s的下沉速度到达的高度越低,大风的出现频率越高;同时300~2500 m风向随时间反气旋偏转能使高空动量持续向近地面传送,对大风的产生和维持起作用,相反300~2500 m风向随时间气旋性偏转,则对高空的动量下传起抑制作用。

Using conventional meteorological data,2.5°x2.5°NCEP data and wind profile radar data,the clear gale weather process in February27th,2015is utilized.It is found that the upper air westerly jet axis is over the Dali Airport.Although the upper air cold advection is weak,but the momentum transmission is the major factor of causing fresh gale.When sinking movement existed from upper to ground,the downdraft carries high momentum from the upper air causing the windy weather.Conversely,the areas from the ground to near700hPa of the airport are updraft,which impeded the passing of the upper air momentum,leading the winds at the airport to end.The result of the Wind profiler data also confirms that the momentum transmission is the major dynamic factor of the gale in February27th.When it is sinking movement from the high ground to the ground,the height of the sinking speed over3m/s is lower,the frequency of the wind is higher.Meanwhile,the wind direction at the height of300~2500m anticyclonic rotated with time can make the altitude momentum continuously transfer to the near surface.It takes effect on the generation and maintenance of the wind.Conversely,the cyclonic deflection makes inhibitory effect on the altitude momentum transmission.