| The Multiple Station Experiment/Thunderstorm Energetic Radiation Array (MSE/TERA) network operating at the International Center for Lightning Research and Testing in Camp Blanding, FL has been used to examine the close RF electric and magnetic field and X-ray environment of cloud-to-ground lightning over a period from 2005 to 2007. Data were obtained for 18 natural and 9 rocket-triggered flashes that are thought to have terminated within or very near the network. The experimental system consisted of electric field sensors (bandwidth of 0.2 Hz to 3 MHz), magnetic field sensors (10 Hz to 3 MHz), dE/dt sensors (DC to 25 MHz), and X-ray sensors (primary type had rise and fall times of 0.17 micros and 0.9 micros, respectively) spread around an area of about 0.5 km2, with the exact number of sensors varying from year to year. For rocket-triggered flashes, the channel-base-current was also measured (DC to 8 MHz). A subset of these measurements, consisting of eight dE/dt sensors and eight X-ray sensors, provided the network with time-of-arrival (TOA) location capabilities. This TOA network, which is the focal point of the present analyses, was used to investigate the spatial and temporal relationship between leader X-ray sources and electric-field-change sources as well as the role of post-leader processes in the production of X rays. The dE/dt portion of the TOA system was also used to track and identify low-altitude processes occurring during the leader phase, attachment process, and return stroke with a higher degree of accuracy than previously possible with similar systems. A comparison of the collected waveforms, combined with these source locations, is used to obtain new insights into some of the more perplexing aspects of lightning, such as the step-formation process, leader propagation near ground, and the attachment process. |
