Recent observations from the flash-continuous broadband VHF lightning interferometer at Langmuir Laboratory

Since 2011 we have been developing a broadband VHF lightning interferometer (INTF) that records multiple entire flashes and utilizes modern cross-correlation and analysis techniques for post-processing the observations. The current generation INTF locates VHF radiation sources with microsecond or sub-microsecond time resolution over 70 dB dynamic range, with up to 0.10 degree angular uncertainty. The INTF has been operated at Langmuir Laboratory for three summer field programs and produces spectacular 2-dimensional observations of flashes that rival and complement those of high speed optical video. Animations of complete flashes show their development in great detail. Coupled with high speed measurements of fast electric changes and LMA observations of the 3-D flash structure and development, the observations are providing a quantum advance in our ability to understand different types of lightning discharges and discharge processes, such as narrow bipolar events, negative leader stepping, positive leader activity and development, precursor events, and lightning initiation.