The thunderstorm characteristics at Beijing capital international airport under different types of large scale environment

Based on thunderstorm observation data at the capital international airport from 2001 to 2014, and conventional observation data, different thunderstorm types were classified.The results show as follows:(1) The thunderstorms happen at the capital airport are dominated by the weaker precipitation, next to the dry-convective thunderstorms.Moreover, the weaker precipitation and dry thunderstorms occur mostly in June.The heavy rainfall and wet convective thunderstorms occur mostly in July.The weak-hail appears in late spring, early summer and autumn.and The hail-with-gale thunderstorms appear in June and July, and the mixed convective thunderstorms appear only in July.(2) Thunderstorms occur the most frequently when there are westerly troughs at 500 hPa, followed by northwest-flow type.When there are westerly troughs, vortexes and northwest-flow at 500 hPa, the thunderstorms are the most frequently caused by convergence line, next to the cold front.When the transversal trough is at 500 hPa, the proportion of thunderstorms triggered by the cold front increased, but no thunderstorms triggered by the topographic convergence existed.When 500 hPa is at the edge of subtropical high and depression trough, the main trigger system on the ground is convergence line.(3) The thunderstorms caused by vortex and northwest-flow are mostly observed in June, but those caused by transversal trough and westerly trough mostly happen in July and August.Westerly trough, vortex and northwest-flow type mostly cause weaker thunderstorms, next to the dry-convective thunderstorms.The most frequent ground system that triggers thunderstorms is convergence line, which mainly concentrates in June, and followed by the cold front which concentrates in May and June, but topographic convergence lines only trigger thunderstorms in July and August.(4) The thunderstorm forming time for transversal trough is (05UTC-12UTC)2-3 h earlier than that of northwest airflow type (08-14UTC), and thunderstorms of vortex have a obvious peak at 12-13UTC, but the thunderstorms of westerly trough mainly concentrate at 8-17UTC.