Diagnostic Analysis of Beijing Persistent High Temperature in 1999
In order to research the evolution of persistent high temperature (PHT) in Beijing from 24th June to 2nd July 1999 and the impact of diabatic heating,the observation data and NCEP/NCAR reanalysis data are analyzed.The results show that:before the occurring of the PHT,the areas from north Europe to southern Baikal were controlled by pressure ridge,accompany with the pressure trough occupied the Central Asia and Northeast China.The pressure ridge on southern Baikal had wide stretch in zonal direction,when it moved eastern,the effect of subsidence warming and diabatic heating increased over Beijing,Beijing was affected by high temperature gradually,and affected for a long time.In the later stage of PHT,the pressure trough which located in Northeast China moved eastward to the Pacific maintained and developed over 120°E to 130°E with intense release of diabatic heating.The diabatic heating increased rapidly with the increasing of altitude below 500 hPa.According to the complete form vertical vorticity tendency equation,the uneven vertical distribution of diabatic heating,as a obvious vorticity source,have remarkable affects on the maintaining of the pressure trough over the sea.Because of the pressure trough,the North China pressure ridge steadily located over Beijing and induced the severe PHT.
persistent high temperaturecomplete form vertical vorticity tendency equationNorth China pressure ridge
NETL
NSTL
万方数据
维普
