Broadband RF Interferometric Mapping and Polarization (BIMAP) Observations of Lightning Discharges: Revealing New Physics Insights Into Breakdown Processes

Journal Article · 06 September 2018 · Journal of Geophysical Research: Atmospheres

DOI: https://doi.org/10.1029/2018JD029096 · OSTI ID:1477665

Shao, Xuan-Min  ^[1]; Ho, Cheng ^[1]; Caffrey, Michael Paul  ^[1]; Graham, Paul Stanley ^[1]; Haynes, Brian  ^[1]; Bowers, Gregory S.  ^[1]; Blaine, William G.  ^[1]; Dingus, Brenda L.  ^[1]; Smith, David  ^[2]; Rasoul, Hamid  ^[3]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. Univ. of California, Santa Cruz, CA (United States)
3. Florida Institute of Technology, Melbourne, FL (United States)

We report broadband radio frequency (RF) interferometry was first introduced in 1996 for lightning studies. The technique has since been improved significantly and has been increasingly widely used in the lightning community. In addition to the interferometry, we now introduce a broadband polarization capability that simultaneously measures the full polarization state of the corresponding RF sources. Polarization observation provides another level of understanding of the discharge processes. In this paper, we describe the new system and present example observations with such a system. Initial observations of impulsive lightning RF pulses, a K-event leader, and the initiating process for an intracloud flash are presented. The impulsive pulses were often linearly polarized and are consistent with conventional breakdown processes, whereas some occasional pulses were elliptically polarized and are likely related to relativistic breakdown processes. The K-event was detected polarized along a section of its channel, and the orientation of the polarization was mostly orthogonal to the channel, apparently due to the preceding charge deposition along the channel. The intracloud flash in this paper was initiated with downward fast positive streamers, and the corresponding signals were linearly polarized, consistent with conventional breakdown processes. The orientations of the polarization were nearly uniformly aligned with the propagation direction of the streamers, indicating a near uniform electric field in the region of the initiating streamers. Lastly, an observation of a cosmic-ray shower is presented.

• Research Organization: Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE; Laboratory Directed Research and Development (LDRD)
• Grant/Contract Number: AC52-06NA25396
• OSTI ID: 1477665
• Report Number(s): LA-UR--18-24675
• Journal Information: Journal of Geophysical Research: Atmospheres, Journal Name: Journal of Geophysical Research: Atmospheres Journal Issue: 18 Vol. 123; ISSN 2169-897X
• Publisher: American Geophysical UnionCopyright Statement
• Country of Publication: United States
• Language: English