Research On The Crosswind Distribution Characteristics And Its Mechanism Of Jiuzhai-huanglong Airport

The crosswind on runway is one of important factors which affect the flight safety.Because of the complex terrain and high altitude, so the nine-yellow airport have bothmountain meteorological Characteristics and plateau meteorological characteristics. Imposedaffecting by of terrain climate, the crosswind often attacks the airport and affects normallytaking off and landing. Based on the ground observations data of nine-yellow airport and itsweather situation maps between 2004 and 2010, the article has studied the airport’smeteorological elements distribution characteristics and the crosswind distributioncharacteristics through mathematical statistical methods. And the article also simulated theairport’s crosswind weather on January 2, 2006 by WRF model. At last we diagnostic analysisthe formation mechanism of the airport’s crosswind in that day. We hope the study can findout some kinds of formation mechanism of the nine-yellow airport’s crosswind and providesome help to the navigation dispatchers and controllers.The results show that, the direction of the nine-yellow airport’s crosswind is essentiallybase on 65°~110°and 245°~290°. What’s more, the two kinds of crosswind complement eachother and take place in wet season and dry season respectively. The speed of nine-yellowairport’s crosswind is essentially base on 4~8m/s. The speed of crosswind over 8m/s oftenoccur in the direction of 65°~110°and 245°~290°crosswind. And the high speed crosswindoften appears in spring and winter. The crosswind at nine-yellow airport often appears from8:00 to 14:00 (UTC), and other time hardly have crosswind.The crosswind of nine-yellow airport is closely related to weather systems. Theprobability of slot line and shear line crosswind is 33.4%, the frontal surface crosswind is18.7%, and the plateau vortex crosswind is 11.3%.The actual data and numerical simulation results show that, the crosswind of nine-yellowairport on that day was produced under the influence of the plateau vortex and the lowpressure tank after the airport. The thermodynamic mechanism of large crosswind is both thesurface sensible heat flux increases and the boundary layer height increases, which makes theatmospheric instability and enhance air turbulent motion. What’s more, the strong coldadvection in the air, on one hand makes the atmospheric stability decreases, on the other handinduces the decreased movement, which makes the high air flow to ground due to themomentum exchange. All of these conditions make the ground wind. The dynamicmechanism of the large crosswind is air flow of the nine-yellow airport with negative vorticityadvection, and the negative vorticity advection increased with height. Thus the air contains downdraft and lower atmospheric layer in horizontal direction is the divergence condition.While the upper atmosphere layer is in convergence condition, such a configuration is veryconducive to generate airflow decreased and upper air downward momentum, so that generatethe ground wind. On the west side of the airport facing two large peaks between the valley isthe terrain factor, and the canyon effect makes the direction of the wind near the ground biason the Westside and the wind speed also increase, which causing the airport’s crosswind in thedirection of 245°~ 290°.