Acoustic vs Interferometric Measurements of Lightning

Abstract:

During the summer of 2015 we acquired acoustic and RF data on several
flashes from thunderstorms over Fort Morgan CO. and Langmuir Laboratory
in the Magdalena mountains of central New Mexico. The acoustic arrays
were located at a distance of roughly 150 m from the interferometers.
Lightning mapping array and slow antenna data were also obtained. The
acoustic arrays consist of arrays of five audio-range and six infrasound
microphones operating at 50 KHz and 1 KHz respectively. The lightning
interferometer at Fort Morgan CO. consists of three flat-plate, 13" diameter
antennas at the vertices of an equilateral 50 m per side triangle. The
interferometer at Langmuir Laboratory consists of three 13" dishes separated
by about 15 m. Both interferometers, operating at 180 Megasamples per
second, use the analysis software and digitizer hardware pioneered by
Stanley, Stock et al. The high data rate allows for excellent spatial
resolution of high speed (and typically high current) processes such as
K-changes, return strokes and dart-leaders. In previous studies, we have
shown the usefulness of acoustic recordings to locate thunder sources as
well as infrasound pulses from lightning. This work will present a
comparison of Acoustic and Interferometric measurements from lightning,
using some interesting flashes, including a positive cloud to ground,
that occurred in these campaigns.