Lightning Imaging with LOFAR

Abstract

Abstract. We show that LOFAR can be used as a lightning mapping array with a resolution that is orders of magnitude better than existing arrays. In addition the polarization of the radiation can be used to track the direction of the stepping discharges.

LOFAR Lightning Imaging: Mapping Lightning With Nanosecond Precision

“…The algorithm that groups pulses into plane wave events has a search time that is initially set to the time of the first pulse observed at that station, on any polarization. Then the algorithm counts the number of antennas that have pulses in a bin that starts at the search time and has D∕c duration in time, where D is the diameter of the station and c is the speed of light in air, accounting for the index of refraction of 1.000293 at standard temperature and pressure (Rüeger, 2002). If four or more antennas have pulses in this bin, then we say that we have found a plane wave event and we fit the times of the pulses on the different antennas to a plane wave model.…”

“…Since LOFAR is capable of nanosecond timing precision, in the future we will need to consider the effects of temperature, pressure, and humidity. The most significant of these is pressure, since at 10 km altitude (pressure of 250 hPa) the index of refraction of air can be as low as 1.000064 (Rüeger, 2002).…”

“…We have developed a pipeline that can use data measured by the LOw‐Frequency ARray (LOFAR) radio telescope to map lightning (Scholten et al, ; van Haarlem et al, ). We will show that this system is capable of mapping lightning in all three spatial dimensions and time, with a relative location accuracy on the order of meters, and can potentially locate as many sources as a lightning interferometer.…”