Data processing procedure using distribution of slopes of phase differences for broadband VHF interferometer

Akita, Manabu; Stock, Michael; Kawasaki, Zen; Krehbiel, P. R.; Rison, W.; Stanley, M. A.

doi:10.1002/2013jd020378

Cited by 32 publications

(34 citation statements)

References 30 publications

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“…Detailed and thorough interferometric investigation of spatial and temporal development of lightning discharges have been reported previously in a number of studies (e.g., Akita et al, ; Rhodes et al, ; Rison et al, ; Shao & Krehbiel, ; Shao et al, ; Stock et al, ). In this paper, we present example observations with the Los Alamos BIMAP system to demonstrate the new capability of the system and to report some new physics insights for some of the discharge processes in the 6 June 2017 IC flash (Figure ).…”

Section: Observation Resultsmentioning

confidence: 91%

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

Shao

Caffrey

et al. 2018

JGR Atmospheres

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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. Finally, an observation of a cosmic‐ray shower is presented.

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Section: Observation Resultsmentioning

confidence: 91%

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

Shao

Caffrey

et al. 2018

JGR Atmospheres

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“…Comparing positive and negative breakdown in lightning discharges, Williams [] indicated that positive breakdown involves much weaker radiation than negative breakdown. We presume that positive breakdown also involves remarkably weaker radiation in LF band than negative breakdown from VHF and UHF lightning observation results [ Shao et al ., ; Kawasaki et al ., ; Akita et al ., ; Stock et al ., ]. Therefore, we speculate that most of sporadic BOLT sources located in the NCR are not source locations associated with positive breakdown; instead, each source location is one part of recoil negative leaders that propagated along the same channel where previous positive leaders propagated, although no clear channel of the recoil leader is imaged in this event.…”

Section: Flashes Mapped By Boltmentioning

confidence: 99%

“…BOLT sources associated with recoil negative leaders moved away from the initiation source location of the IC with time at an almost constant altitude of 6 km. Taking into account that lightning discharges propagate as a bidirectional tree [ Mazur and Ruhnke , ; Kawasaki et al ., ; Akita et al ., ; Stock et al ., ], it is likely that undetectable positive leader developed horizontally at about 6 km altitude from the initiation point of this flash. It appears that the positive leader at least had two branches.…”

Section: Flashes Mapped By Boltmentioning

confidence: 99%

“…BOLT sources associated with recoil negative leaders moved away from the initiation source location of the IC with time at an almost constant altitude of 6 km. Taking into account that lightning discharges propagate as a bidirectional tree [Mazur and Ruhnke, 1998;Kawasaki et al, 2002;Akita et al, 2014;Stock et al, 2014], it is likely that undetectable positive leader developed horizontally at about 6 km altitude from the initiation point Figure 8a, a circle, plus signs, and squares, respectively, correspond to the first BOLT source location for this event, sporadic BOLT sources in the NCR, and the other BOLT source locations. In Figure 8b, all squares correspond to the VHF source locations.…”

Section: 042mentioning

confidence: 99%

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Initial results of LF sensor network for lightning observation and characteristics of lightning emission in LF band

Yoshida

Ushio

et al. 2014

JGR Atmospheres

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We have been developing an LF sensor network called Broadband Observation network forLightning and Thunderstorm (BOLT), to image the structure of lightning discharges in 3D using time of arrival (TOA) technique. This paper documents initial results and characteristics of BOLT source locations for further understanding of LF radiation associated with lightning. Theoretical reduced Chi-square distribution fitted to BOLT observation data indicates a root mean square (rms) timing error of about 200 ns for each sensor. Monte Carlo simulations of BOLT indicate that at an altitude of 5000 m the standard deviations for horizontal differences between a known source and a location that the BOLT algorithm produces are less than 200 m, and vertical differences are less than 400 m in most of the network. Furthermore, comparison of BOLT and VHF source locations arriving at the same site within 5 μs indicates that the average difference for elevation direction is 0.73°with a standard deviation of 3.64°, and that for the azimuth direction is 0.58°with a standard deviation of 1.98°. Lightning flash processes of intracloud (IC) and cloud-to-ground (CG) flashes, including preliminary breakdown pulses, negative leaders, breakdown in the negative charge region (NCR), and an attempted leader, are well imaged by BOLT. Normalized amplitudes in E-field change waveform of BOLT sources associated with negative leaders and breakdown occurred in the NCR do not have significant difference, implying that most BOLT sources in the NCR might be associated with negative recoil leaders.

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“…2). Because a lightning leader develops bidirectionally [25,26], positive leaders might have developed in the opposite direction of the negative leader. In this event, a positive leader might have developed below the initiation point.…”

Section: An Ic Dischargementioning

confidence: 99%

Three‐dimensional radio images of winter lightning in japan and characteristics of associated charge structure

Yoshida

Yoshikawa

Adachi

et al. 2018

IEEJ Transactions Elec Engng

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We conducted lightning observational campaigns using a three‐dimensional (3D) lightning mapper called the Broadband Observation network for Lightning and Thunderstorms (BOLT) and C‐band radar to further understand the distinct characteristics of winter lightning in the coastal area of the Sea of Japan. We succeeded in locating 3D intracloud (IC) flashes, cloud‐to‐ground (CG) flashes, and upward lightning during winter. The basic characteristics of winter lightning, such as leader speeds and charge structure associated with an IC discharge, are similar to summer lightning. A noticeable difference between the winter lightning and the summer lightning is that the altitudes of the source locations associated with winter lightning are substantially lower than those associated with summer lightning. We performed a statistical comparison of winter and summer lightning. This comparison shows that the BOLT source altitude distributions during winter and summer peak at 2.1 and 7.5 km, respectively. Conversely, the distributions of the BOLT temperatures, which are the temperatures corresponding to the BOLT source altitudes, during both winter and summer show similar trends and have large values near −10 °C. These results indicate that a similar charge separation process, likely a noninductive charging mechanism, primarily contributes to thunderstorm electrification during both winter and summer. We show that the horizontal extent of the winter flashes is substantially larger than that of the summer flashes. This result implies that the charge regions in winter thunderstorms cover a wide area and, therefore, produce CG flashes with large charge transfers. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

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Data processing procedure using distribution of slopes of phase differences for broadband VHF interferometer

Cited by 32 publications

References 30 publications

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

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

Initial results of LF sensor network for lightning observation and characteristics of lightning emission in LF band

Three‐dimensional radio images of winter lightning in japan and characteristics of associated charge structure

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