Abstract:Using radar and intensive AWS (automatic meteorological station) data as well as VDRAS data whose temporal resolution is 12 min, horizontal and vertical resolutions are respectively 3 km and 1 km or so, the dynamical and thermodynamic processes of thunderstorm systems that are impacted by sea breeze convergence lines are investigated by analyzing the two cases triggered by pure sea breeze convergence line and by the merged sea breeze convergence and existing thunderstorm system. The results showed that: (1) When the environmental wind system is very weak, the moving sea breeze speed of Tianjin coastal sea breeze into the inland is about 15-18 km·h-1, and, after the leaving of sea breeze, temperature there decreases and humidity increases. (2) The sea breeze convergence line cooperates with the surface highly unstable region, triggering and strengthening the thunderstorm system, so that the thunderstorm warning can be 2 h in advance. (3) Thunderstorm cell forms near the sea breeze convergence line, which corresponds to the mesoscale vertical circulation in the frontal surface (to the sea side) of the tilting sea breeze front. (4) After sea breeze convergence line merges with the thunderstorm, the severely development of the thunderstorm is attributed to the accumulated water vapor near the sea breeze and the large zone of convergent updraft.