Electric Field Characteristics of Subsequent Return Strokes, M-Components, and ICC-Pulses From Negative Upward Lightning Measured at the Peissenberg Tower.

In this paper, we present the currents, which have been measured since 2008 at the new top structure of the Peissenberg Tower, Germany, and the associated electric fields in a distance of about 180 m from the tower. The study comprises 17 negative lightning, which contained 44 subsequent return strokes, 108 initial continuous current (ICC)-pulses, and 26 M-components. The analysis, based on the current waveform, revealed three different types for both the M-component current and the ICC-pulse. The impulsive current of type 1 has a more or less symmetrical wave shape. For this type, the electric field occurred on average 15.7 μs prior to the current pulse. The impulsive current of type 2 has a bipolar wave shape with current reversal. The impulsive current of type 3 has a wave shape, which exhibits a fast rise to peak and a much longer decay to low current values. For all types of impulsive currents (return strokes, ICC-pulses, and M-components), the electric field exhibits a first field change (ΔE1) followed by a second field change (ΔE2) of opposite polarity. For the ICC-pulses and M-component currents of types 1 and 3, the first field change (ΔE1) has typically an initial slow-rising section, which is followed by a fast-rising section. The transition point was time-correlated with the onset of the current. The transition point was at about ΔE1/3 for type 1 and at about ΔE1/2 for type 3. For type 2, the onset of the current pulse occurred during the second field change (ΔE2) of opposite polarity. Similar to type 1 and 3 pulses, the slow-rising electric field changed into a fast-rising electric field. The transition point for type 2 pulse was at about ΔE2/3. From the 44 subsequent return strokes, 8 of them contained one negative M-component of type 1. In that case, the M-component current was extremely strong. The arithmetic mean (AM) was 8.5 kA (GM: 5.4 kA) for the peak current and 747.8 mC (GM: 614.0 mC) for the transferred charge. The return stroke was also very strong, with an AM of 16.7 kA for the peak current (GM: 15.0 kA). In comparison, the AM was 10.4 kA (GM: 8.3 kA) considering all subsequent return strokes. [ABSTRACT FROM AUTHOR]