Relationship between Lightning Activities and Radar Echoes of Squall Line Convective Systems

The relationships between the lightning activities and the radar reflectivity intensities of seven severe squall lines, which occurred in Beijing from 2015 to 2017, were analyzed. The analysis was done based on three-dimensional lightning location data from Beijing Broadband Lightning Network (BLNet) and the S-band Doppler radar. The results show that lightning flashes are mainly located in the convective leading line and centered in the strong echo region, with reflectivity greater than 30 dBZ, and a small part of lightning flashes distributed in the trailing stratiform region. Based on the three-dimensional lightning structure, the lightning flashes are mostly concentrated in the range of 6–11 km height layer. Using the radar echo volume with reflectivity >30 dBZ (V_30dBZ) between the 0 and −30°C level, as a strong convection index to reflect both the depth and area of strong convection, we found that of all seven squall lines, the trend of the lightning frequency and V_30dBZ evolution showed some relationship. For five squall lines, the lightning frequency peak is the same or earlier than that of V_30dBZ, the lagged correlation coefficient is higher than 0.61, and the lightning frequency is earlier than V_30dBZ, with a leading time from 0 to 96 min. For the other two cases, the lightning frequency peak lags V_30dBZ at 30 and 60 min, respectively. The results are significant for understanding lightning activity and convection intensification and provide a scientific basis for lightning data assimilation in numerical weather prediction.