耦合重力波对昆明一次低空大风灾害的影响分析OA

On March 27,2024,a disastrous gust damaged the terminal building at Kunming Changshui Interna-tional Airport in Yunnan,China.The role of coupled atmospheric gravity waves in this event is examined using conventional surface meteorological observations,high-resolution mesoscale surface network,upper-air sound-ing data,ERA5 reanalysis data and FY-2G geostationary satellite imagery.The results show that:(1)After solar heating in the morning,an atmospheric gravity wave originating over the Hengduan Mountains propagated south-eastward under the influence of westerly flow.Meanwhile,another gravity wave generated over the Ailao Moun-tains propagated northeastward.These two gravity waves met near 100.56°E,25°N about 09:53(Beijing Time),producing a significant coupling effect.(2)Based on the force analysis within a statically stable atmospheric lay-er and the initial perturbations induced by orographic lifting of the background flow,the analytical mathematics formula of the gravity wave was derived.Using satellite observations and infrared cloud imagery,the key param-eters of each gravity waves including significant amplitude,wavelength,intrinsic frequency,and phase speed-were quantitatively obtained.(3)By harmonic analysis,the coupled wave with its zonal and meridional components were determined.The coupled wave induced substantial vertical motions above the airport:the zonal component generated a downward motion of 18 m·s-1,contributing positively to the surface winds,while the meridional component produced a weaker upward motion of 1 m·s-1,exerting a negative contribution.(4)The comprehensive effect of the coupled gravity waves and the DCAPE releasing generated a strong subsiding air-flow,which enhanced the downward transport of upper-level jet momentum.This momentum transition was combined with the near-surface horizontal wind field,ultimately resulting in a catastrophic surface gust reaching 86.5 m·s-1,causing severe structural damage to the main terminal building of Kunming Airport.Quantitative as-sessment indicates that gravity waves contributed approximately 19.65%to the total wind speed.In contrast,the presence of either gravity wave A or B alone without coupling effect would account for a maximum wind speed contribution of only about 10 m·s-1.The role of gravity wave coupling is of critical in intensifying subsidence and promoting the extreme low-level wind hazards.