The impact and source of typical sand and dust storms weather on air quality in the Beijing-Tianjin-Hebei region

Abstract Based on ambient air quality monitoring data, remote sensing data and sea level pressure field data, the impact of typical sand and dust storms (SDS) on urban air quality in the Beijing-Tianjin-Hebei region was analyzed using the HYSPLIT backward trajectory model, potential source contribution function (PSCF) and concentration-weighted trajectory (CWT).Furthermore, the WHCWT pollution source model was also introduced to simultaneously analyze pollution sources in multiple cities. The research results show that on March 15, 2021, the Beijing-Tianjin-Hebei region experienced an SDS lasting 28 hours, with Zhangjiakou, Beijing and Tianjin all showing strong SDS characteristics. A cold front passed through northern and northeastern China, generating strong winds and causing a drop in temperature near the front and its frontal zone.This further intensified and expanded the impact of the SDS. The strong winds associated with the cold front facilitated the transport of dust to the Beijing-Tianjin-Hebei region, leading to widespread SDS events. During the SDS, the hourly concentrations of PM 10 and PM 2.5 in 13 cities in the Beijing-Tianjin-Hebei region showed a "single peak" variation, The PM 10 concentration was 2.8 to 60.8 times that of the PM 2.5 concentration during the same period. Before the PM 10 concentration reached its peak,the ratio of PM 2.5 to PM 10 showed a downward trend, and the trough of this ratio lagged behind the peak of PM 10 by 1 to 2 hours. In addition, the hourly concentrations of SO 2 , NO 2 and CO decreased significantly during the SDS, while the O 3 concentration showed an upward trend after the SDS finished. The combined effect of the Mongolian cyclone and the high-pressure system caused the air mass to move southeast,impacting the Beijing-Tianjin-Hebei region with the SDS. This study can provide a reference for predicting the impact of SDS on air quality in 13 cities in the Beijing Tianjin Hebei region.