Electric field derivative waveforms from dart‐stepped‐leader steps in triggered lightning. Issue 18 (18th September 2014)

• Record Type: Journal Article
• Authors: Gamerota, W. R.; Uman, M. A.; Hill, J. D.; Ngin, T.; Pilkey, J.; Jordan, D. M.
• Is Part Of: Journal of geophysical research. Volume 119:Issue 18(2014)
• Page Start: 10, 844
• Page End: 10, 858
• Publication Date: 2014-09-18
• Subjects: Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1002/2014JD021919
• Languages: English
• ISSNs: 2169-897X

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>Electric field derivative (d<italic>E</italic>/d<italic>t</italic>) pulse waveforms from dart‐stepped‐leaders in rocket‐and‐wire triggered lightning, recorded a distance of 226 m from the channel base, are characterized. A single d<italic>E</italic>/d<italic>t</italic> pulse associated with a leader step consists of a fast initial rise of the same polarity as the following return stroke followed by an opposite polarity overshoot of smaller amplitude and subsequent decay to background level, without superimposed secondary pulses. A "slow front" often precedes the fast initial rise. For 47 single d<italic>E</italic>/d<italic>t</italic> leader pulses occurring during the final 15 µs of 24 dart‐stepped‐leaders, the pulse mean half‐peak width was 76 ns, mean 10‐to‐90% risetime 73 ns, and mean range‐normalized peak amplitude 2.5 V/m/µs. For integrated d<italic>E</italic>/d<italic>t</italic>, the mean half‐peak width was 214 ns and the mean range‐normalized peak amplitude 0.21 V/m. Most dart‐stepped‐leader d<italic>E</italic>/d<italic>t</italic> pulses are more complex than a single pulse. Interpulse interval and average peak amplitude range normalized to 100 km were measured for both single and complex d<italic>E</italic>/d<italic>t</italic> pulses during the final 15 µs of 10 dart‐stepped‐leaders preceding triggered return strokes with peak currents ranging from 8.1 to 31.4 kA. The average range‐normalized d<italic>E</italic>/d<italic>t</italic> and numerically integrated d<italic>E</italic>/d<italic>t</italic> (electric field) peak amplitude increased from 0.9 to 4.9 V/m/µs and 0.13 to 0.47 V/m, respectively, with increasing return stroke peak current while the interpulse interval remained relatively constant at about 2 µs. Strong positive linear correlations were found between both average range‐normalized peak pulse amplitude and interstroke interval versus the following return stroke peak current.</p> </abstract>