Interactions and Multifrequency Radiation Characteristics of Bidirectional Leaders in Altitude‐Triggered Lightning

Abstract

Abstract Altitude‐triggered lightning provides favorable conditions for the research of bidirectional leader system. In the summer of 2023, altitude‐triggered lightning experiment was conducted on the Field Experiment Base on Lightning Sciences, China Meteorological Administration. The multifrequency radiation characteristics of bidirectional leaders and the interactions of both ends during the propagation are analyzed. Specifically, the discharge processes that produce LF‐MF magnetic radiations from bidirectional leaders are revealed by high‐speed images, and these LF‐MF radiations correspond to the VHF radiations generated by bidirectional leaders well. Unlike the strong correlation between LF‐MF radiation strengths and discharge intensities, the VHF radiation strengths exhibit significant variation even among similar‐intensity discharge events, as VHF radiations correspond to the random and microscopic discharge processes associated with streamers. Furthermore, the changes in leader speed and channel brightness before and after the initiation of bidirectional leaders indicate that the development of the two ends of bidirectional leaders is mutually reinforcing.

Keywords

• altitude‐triggered lightning
• upward positive leader
• downward negative leader
• bidirectional leader propagation
• low‐medium frequency magnetic field