Abstract: Using radar CR data and ECMWF ERA5 data,39 squall lines in the Beijing-Tianjin-Hebei region under the background of cold vortex in the recent 16 years were identified and analyzed statistically. The results show that under the background of the cold vortex,most of the squall lines affecting the Beijing-Tianjin-Hebei region occurred in June and July,with obvious daily variations. Most of them formed from the afternoon to the evening,after which they entered the development and mature stage. They usually ended at night,with a life span of 3 to 4 hours. Most of the squall lines were generated in the junction of the central mountain range plain and mountainous areas of the Beijing-Tianjin-Hebei region,matured in the plain area and dissipated in the southeast coastal area. Their moving direction was mostly southeast,and their moving speed was mostly between 8-16 m/s. The generation and dissipation modes were mostly BL type and RBL type. Most of the squall lines occurred in the formation and strengthening stage of the cold vortex,located in the southeast direction of the cold vortex,500-2 000 km away from the center of the cold vortex. The squall lines were affected by the cold vortex indirectly more than the cold vortex directly.

Key words: cold vortex, squall lines, Beijing-Tianjin-Hebei region, statistical analysis