Evolutionary Characteristics of Charge Structure in an Atypical Bottom‐Heavy Thunderstorm Over the Central Tibetan Plateau

To get more insights into the charge structure inside thunderstorms over high plateau regions, this poses significant challenges. Based on the data from the high‐precision lightning VHF interferometer, C‐band Doppler radar and multi‐band electromagnetic field observation, this study presented the complete evolutionary characteristics of charge structure in an atypical bottom‐heavy thunderstorm producing solely intra‐cloud (IC) lightning over the Tibetan Plateau (TP). A persistent inverted dipole and a tripolar charge structure with a larger‐than‐usual lower positive charge center (LPCC) coexisted within this thunderstorm. At the initial and the sustained weak convection stages, the thunderstorm demonstrated a negative dipolar charge structure. As the convection further developed into a mature stage, an additional positive charge region appeared in the upper level, forming a tripolar charge structure with a larger LPCC at the bottom of an intense convective region. In contrast, a neighboring convective region preferentially developed the upper‐level dipole charge structure rather than forming an LPCC. The IC flashes, with a maximum of 4 fl/min, predominantly occurred as negative IC flashes originating from the lower negative dipole, while few positive IC flashes occurred between the upper dipole charge structure. The LPCC was primarily associated with positive charged graupel particles. The middle negative charge region involved substantial negative charge carried by ice crystals and snow aggregates with graupel particles acting as the charge carrier in its upper part. The upper positive charge region was mainly contributed by ice crystals and snow aggregates.