2024年5月30日首都机场雷暴大风成因与风速估算OA

On 30 May,2024,a sudden extreme thunderstorm gale occurred at the Beijing Capital International Airport(BCIA),with maximum wind gusts reaching gale force 11.Utilizing Doppler radar data,automatic weather station observations at BCIA,ERA5 reanalysis data,and conventional meteorological data,this study analyzes the causes of this event,and further evaluates the methods for estimation of extreme surface wind-speeds.The results indicate that under the background of cold vortex circulation in Northeast China,there is an environment configuration with the dry and cold upper troposphere and the warm and humid lower troposphere,which is a favorable environment configuration for strong convection.The thermodynamic contract between the upper and lower layers was particularly pronounced,and the 850 hPa level was significantly drier than the climatological mean for severe thunderstorm occurrence in North China.The moderate to strong vertical wind shear at 0-6 km layer supported the development of severe convective weather such as squall lines featuring minimal precipitation and high winds.A diagnostic analysis revealed that the downward momentum transfer from mid-level strong convective clouds played a crucial role in generating damaging surface winds.Radar observations at 14:40 Beijing Time showed that a wind core(about 20 m·s-1)located at 4-5 km gradually descended to 0.4-1 km through momentum transfer.Accelerated by both the release of downdraft convective available potential energy(DCAPE)and evaporative cooling,the wind core intensified to 30 m·s-1.As the wind core descended from 0.4 km to the surface,the opposing effects of diminishing downdraft acceleration and increasing urban surface friction resulted in a basically stable wind speed.It is concluded that tracking the descent of the mid-level strong wind core via radar or monitoring the propagation velocity of cold pool outflow boundaries provides an effective means for estimating thunderstorm gale intensity at the airport.