关键词: 飑线, 中尺度, 不稳定层结, 雷达回波特征

Abstract:

Based on conventional observation data，automatic meteorological station data and radar data，the mesoscale analysis of a squall line process influenced on Tangshan area on August 4，2013 was performed．The results showed that the 500 hPa upper trough was the main effect system on the squall line induced by a ground mesoscale convergence line．The invasion of dry and cold air from the middle troposphere and the convergence of warm and moist air from the lowlevel troposphere enhanced the instability of atmosphere．The low‐level convergence and high‐level divergence further strengthened the vertical movement．The vertical wind shear at the middle and low layer was beneficial to the development，enhance and maintain of the squall line．Some mesoscale structure features can be identified on the radar echo map，such as mesoscale convergence line in middle and low level，bow echo，head wind areas，which were all actual indicative to the severe convective weather．

Key words:  squall line, mesoscale, instability stratification, radar echo characteristic