Observations of Rocket Triggered Lightning Discharge in Winter Thunderstorms in Japan Using a Broadband VHF Interferometer

Winter lightning in Japan presents unique scientific challenges and opportunities, particularly with advanced mapping technologies. This study investigates rockettriggered lightning (RTL) using a broadband VHF interferometer system to analyze upward positive leader. The system, operating at a high sampling rate with continuous recording, enabled locating of lightning discharge dynamics in winter thunderstorms. The results suggest that flashes without a return stroke occur when the upward positive leader does not reach the main negative charge region. Furthermore, the initial stage of this case was a unidirectional leader rather than a bidirectional leader, and the positive breakdown detected by the VHF interferometer indicated a wider discharge path. This case involves a flash without a return stroke but with continuous current. In other words, although it involves continuous current that is likely to cause damage to industrial equipment and power distribution facilities, it does not involve a return stroke, so it is highly likely that it cannot be detected by lightning location systems such as Lightning location system. These findings contribute to a deeper understanding of lightning discharge in winter thunderstorm behavior and its impact on infrastructure.