Some Parameters of Correlated Current and Radiated Field Pulses from Lightning to the Gaisberg Tower

Simultaneous measurements of lightning current and associated radiated electromagnetic field are of fundamental interest for Various applications in lightning research. These data can be used for the evaluation of return stroke (RS) models or to investigate the so-called tower effect when lightning hits ail elevated object. In this paper, we show the results of simultaneous measurements of current Pulses from lightning strikes on the instrumented Gaisberg tower (Austria) and the correlated vertical E-field components at a distance of 78.8 and 108.7 kill, respectively. We have analyzed some main lightning current parameters (peak current I-p. 30-90% rise time TI_30-90, and full width at half maximum T-I_FWHM) and the time-correlated field waveform parameters (E-p, 30-90% rise time TE-30-90, T-E_FWHM, and the peak-to-zero time T-E_PTZ). With a geometric mean of T-I_FWHM = 19 mu s and I-p = 9.6 kA (N = 73) of the RS current Pulses used in this study, those strokes are very similar to the strokes in triggered lightning in Florida and Alabama [1]. With a T-E_PTZ of about 10 mu s, the zero-crossing time of the radiated E-fields from (he tower strokes are significantly shorter than the typical values of 30 - 40 mu s (e.g. [2]). Correlation between the current and field parameters T-I_FWHM versus T-E_FWHM and T-E_PTZ respectively is low (R-2 = 0.29 and 0.14). We assume that the relatively short lightning channel in the case of the RSs in object-triggered upward flashes is the main reason for the observed short zero-crossing time. (C) 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Soils, Inc.