Leader/return-stroke-like processes in the initial stage of rocket-triggered lightning

Abstract

Linear streak film, video, current, and electric field records from nine triggered-lightning flashes are analyzed to examine the process of cutoff and reestablishment of current during the initial stage of rocket-triggered lightning. All of the data were acquired at the International Center for Lightning Research and Testing at Camp Blanding, Florida, in 2002 and 2003. It is shown that in some rocket-triggered lightning events, the process of current cutoff and reestablishment during the initial stage is similar to a leader/return-stroke sequence, although the currents in this process are typically an order of magnitude smaller (1 kA or so) than those in a triggered or natural lightning subsequent stroke (10-15 kA). The events were separated into two groups based on observed characteristics, with the duration of the current cutoff interval being the primary differentiating characteristic. In some cases, two or three failed attempts at current reestablishment prior to the successful resumption of current flow in the channel were observed. Currents associated with the unsuccessful attempts were typically an order of magnitude smaller (100 A or so) than in the process which finally reestablished the current. Copyright 2006 by the American Geophysical Union.