Three Types of M-Components and ICC-Pulses and their Characteristics obtained from Negative Upward Lightning Measured at Peissenberg Tower

In 2007 the top structure of the Peissenberg Tower was modernized and since 2008 lightning currents have been measured with this new top structure. This paper deals with a detailed analysis of 45 negative upward flashes, including 60 return strokes and 264 impulsive currents, measured between 11/21/2008 and 08/09/2017. 185 of this impulsive currents occurred during the initial continuous current (ICC), called ICC-pulses, and 79 occurred during the continuing current (CC) following return strokes, called M-components. The goal of the analysis of these impulsive currents was to figure out their characteristics. It was found out, that current pulses during the ICC resemble closely M-component currents. Further the analysis revealed three different types of waveforms for impulsive currents occurring during the ICC as well as during the CC. The first type is characterized by a nearly symmetrical waveform. 130 out of 264 impulsive currents were of this type one. 68 impulsive currents of the second type revealed a bipolar waveform with current reversal. Impulsive currents of the third type show a waveform, characterized by a fast rise to peak and a much longer decay to lower current values. 23 out of 264 impulsive currents were of type three. Furthermore we found four combinations (A-D) of at least two pure impulsive currents of type 1-3. In total 43 out of 264 impulsive currents were combined impulsive currents.