Diagnosis of severe dust weather process based on multi-source observational data
Study utilized multi-source data including vertical observations from lidar,conventional atmospheric pollution,meteorological observations,satellite observations,and reanalysis data,combined with backward tra-jectory simulations and weather diagnostic analyses to investigate the structural characteristics and evolution mechanisms of a severe dust event occurring in northern China from March 21st to 23rd,2023.The results indi-cate that under the influence of Mongolian cyclones,the event spread from northwest to southeast,passing through Bayannur City,Hohhot City,and Zhangjiakou City before reaching Beijing.During this period,the peak PM10 concentration in Beijing reached 1 667 μg·m-3,significantly lower than the peak concentration in its upstream neighbor,Zhangjiakou City(9 993 μg·m-3).The reasons for this can be attributed to the significant at-tenuation of dust concentration after passing through Zhangjiakou due to the obstruction of the Yan Mountains.Furthermore,backward trajectory results indicate that some dust particles were transported northeastward after leaving Zhangjiakou,influenced by the southwest airflow ahead of the cyclone's front.The vertical structure of the dust event shows that dust transport heights over Beijing can reach 6 000 m.The vertical movement of the tro-posphere is a sandwich-like structure,characterized by subsidence from near the surface to 920 hPa,ascent from 920 hPa to 700 hPa,and subsidence again from 650 hPa to 450 hPa.This sandwich-like structure is not condu-cive to dust settling in Beijing area,which is the key reasons for the low dust concentration in Beijing.The tem-poral evolution of the dust event indicates a rapid increase followed by a slow decrease in the backscattering coef-ficient derived from Beijing lidar data,while the PM2.5/PM10 ratio decreased from 0.73 to 0.18.
NETL
NSTL
万方数据
