白云机场终端区一次热力对流诊断分析

A Diagnostic Analysis of a Thermal Convection at the Terminal Area of Baiyun Airport

利用白云机场气象观测资料和0.5°×0.5°的ERA-interim再分析资料,对2019年7月22日发生在白云机场终端区夏季的一次热力对流天气进行诊断分析,结果表明:西南低涡有利于西南暖湿气流的输送,中层气旋和低压槽使大气处于不稳定环境,地面存在中尺度辐合线,为对流提供抬升条件;白云机场上空大气层结不稳定,有能量锋区相配合,持续高温增大不稳定能量;涡度平流和散度场上正下负的配置,有利于触发次级环流,为对流发展提供动力机制。小尺度涡旋扰动不断过境,为雷暴持续性激发提供有利机制。CDM对流临近预报产品对该次热力雷暴预报效果良好。

Using the meteorological observations of the Baiyun Airport and 0.5°×0.5°ERA-interim reanalysis data,this work runs a diagnostic analysis of a thermal convection weather over the terminal area of the airport that took place on July 22,2019.The result is shown as follows.A southwest vortex was favorable for the transport of a warm and humid southwesterly,a mid-level cyclone and a low-pressure trough made the atmosphere unstable,and there was a mesoscale convergence line at the surface,all conducive to the lifting of convection.As the atmospheric stratification was unstable over the airport and with the support of an energy front,persistently high temperature increased the instability energy.The allocation that both the vorticity advection and divergence field are positive at the upper level but negative at the low level made it easy to trigger the secondary circulation that dynamically drove the convection.Fine-scale vortexes and disturbances kept moving across the area of interest,which was a favorable mechanism for persistent triggering of the thunderstorm.The convection nowcasting product of CDM performed well in forecasting this thermal thunderstorm.