Evolution of charge structure in a thunderstorm over South China

South China is one of the most active regions for thunderstorms in China, yet, research on the charge structure of thunderstorms in this area remains limited. This study utilized lightning data from the Guangdong Lightning Mapping Array and radar observations to examine the charge structure of a thunderstorm that occurred in South China on June 16, 2021. The thunderstorm's charge structure underwent transitions from a dipole in the early stage, a tripole during its mature stage, and back to a dipole in the dissipation period. The heights of the two charge regions in the initial dipolar charge structure increased rapidly. Throughout the storm, the lower positive charge region in the tripolar charge structure was involved in 11.8% of the total 1075 recorded flashes. The average distances between the high-density charge cores of the three charge regions were 2.8 km and 2.6 km from top to bottom. As the storm entered its dissipation stage, the upper positive charge region descended significantly more slowly than the larger particles, as indicated by the continuous decrease in radar reflectivity in this region. The dominant hydrometeors in the upper positive, middle negative, and lower positive charge regions were dry aggregated snow, graupel, and larger-size graupel, respectively, occupying approximately 81%, 67%, and 70% of the total volume in each region. Over the course of the three stages—when the lower positive charge region was initially uninvolved in discharges, became involved, and then ceased participation—the primary microphysical processes in the precipitation beneath the convective core were collisional breakup, size sorting, and collision-coalescence, respectively.