Characteristics of Magnetic Field Pulses in Lightning Measured by the GALILEO Instrument.

A compact lightning measuring instrument designed for the Galileo Jupiter Probe Mission has been operated intermittently for several years to monitor the magnetic field signals of Earth lightning. The instrument performs spectral measurements in three narrowband channels at 3, 15 and 90 kHz (frequency domain) and waveform measurements (time domain) in the band 0.01-100 kHz. In the time domain, the instrument outputs the statistical distributions of pulse amplitude, pulse duration and inter- pulse gaptime accumulated during a variable but preset measuring period along with a picture of the 1 ms window containing the largest amplitude waveform observed during the measured period.