Some characteristics of lightning activity and radiation source distribution in a squall line over north China

Using the data from SAFIR3000 lightning detection network and Doppler weather radar, the characteristics of lightning activity in a squall line on July 31, 2007 were analyzed. In this study, the lightning activity and inferred charge structure of squall line were obtained. Our results reveal that: 1) the horizontal projection of the lightning radiation sources mainly corresponded to the high radar reflectivity area of the squall line, and 2) the vertical distribution of the lightning radiation sources developed from two layers into three layers. At the developing stage of squall line, the upper lightning radiation sources were centered at 11 km MSL, while the lower radiation sources were located at 4 km MSL. Assuming that the maximum lightning radiation sources were corresponding to the positive charge region, the squall line showed a dipole charge structure with an upper positive charge region and a lower negative charge region. At its mature stage, the entire squall line was characterized by a multi-layer charge structure with three layers of positive charge at 5 km MSL, 9.5 km MSL, and 13 km MSL, and a two-layer negative charge region at 7 km MSL and 11 km MSL.