Time resolved 3Dinterferometric imaging of a section of a negative leader with LOFAR

Abstract

We have developed a three dimensional (3D) interferometric beamforming technique for imaging lightning flashes using Very-High Frequency (VHF) radio data recorded from several hundreds antennas with baselines up to 100~km as offered by the Low Frequency Array (LOFAR). The long baselines allow us to distinguish fine structures on the scale of meters while the large number of antennas allow us to observe processes that radiate at the same intensity as the background when using a time resolution that is close to the impulse-response time of the system, 100~ns. The new beamforming imaging technique is complementary to our existing impulsive imaging technique. We apply this new tool to the imaging of a four stepped negative leaders in two flashes. For one flash, we observe the dynamics of coronal flashes that are emitted in the stepping process. Additionally, we show that the intensity emitted in VHF during the stepping process follows a power-law over 4 orders of magnitude in intensity for four leaders in two different lightning storms.

8 pages, 5 figures

References in corpus (4)

• Experimental study on hard X-rays emitted from metre-scale negative discharges in air
• Radio emission from negative lightning leader steps reveals inner meter-scale structure
• Calibration of the LOFAR low-band antennas using the Galaxy and a model of the signal chain
• Adaptive Weighting in Radio Interferometric Imaging

Cited by in corpus (3)

• Interferometric imaging of Intensely Radiating Negative Leaders
• Aperture correction for Beamforming in radiometric detection of ultra-high energy cosmic rays
• Measuring the locations and properties of VHF sources emitted from an aircraft flying through high clouds