Broadband and narrowband RF interferometers for lightning observations

Kawasaki, Zen; Mardiana, Redy; Ushio, Tomoo

doi:10.1029/1999gl011058

Cited by 48 publications

(26 citation statements)

References 9 publications

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“…The standard deviation of the best fit Gaussian distribution for elevation is 3.64°, and that of the azimuth difference is 1.98°. These values are substantially less than the previously reported standard deviations between VHF DITF and a narrow‐band interferometer [ Kawasaki et al ., ].…”

Section: Resultsmentioning

confidence: 99%

“…The distribution is clearly fitted to the theoretical Gaussian distribution in Figure 6, implying that the major error sources of BOLT and VHF DITF were statistical errors. Comparing VHF DITF observation data with narrow band interferometer images, Kawasaki et al [2000] reported that the location difference between these two sensors was less than 2°with a standard deviation of 5°for elevation and less than 1°with a standard deviation of 4.5°for azimuth. Therefore, the standard deviation discussed here is apparently less than the standard deviations between VHF DITF and narrow-band interferometery source locations.…”

Section: Comparison Of Source Locations Estimated By Bolt and Vhf Ditfmentioning

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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Section: Resultsmentioning

confidence: 99%

Section: Comparison Of Source Locations Estimated By Bolt and Vhf Ditfmentioning

confidence: 99%

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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“…The location of lightning radiation sources in two dimensions (elevation and azimuth) can be determined by using independent non-collinear baselines in an orthogonal antenna array, as shown in Figure 1. The technique here is fundamentally the same with the interferometer developed by other research groups [Ushio et al, 1997;Kawasaki et al, 2000;Stock et al, 2014].…”

Section: Short-baseline Vhf Radiation Location Systemmentioning

confidence: 99%

Characteristics of a rocket‐triggered lightning flash with large stroke number and the associated leader propagation

et al. 2014

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A negative lightning flash with 16 leader-return stroke sequences, triggered in the summer of 2013 using the classical rocket-and-wire triggering technique, was examined with simultaneous two-dimensional (2D) imaging of very high-frequency (VHF) radiation sources, channel-base current measurement, broadband electric field waveforms and high-speed video images. A total of 28.0 C negative charge was transferred to ground during the whole flash, and the charge transferred during the initial stage was 4.9 C, which is the weakest among the triggered lightning flashes at the SHandong Artificially Triggering Lightning Experiment (SHATLE). The peak current of 16 return strokes ranged from 5.8 to 32.5 kA with a geometric mean of 14.1 kA. The progression of upward positive leader and downward negative (dart or dart-stepped) leaders was reproduced visually by using an improved short-baseline VHF lightning location system with continuous data recording capability. The upward positive leader was mapped immediately from the tip of the metal wire during the initial stage, developing at a speed of about 10 4 m/s without branches. The upward positive leader and all the 14 negative leaders captured by the 2D imaging system propagated along the same channel with few branches inside the cloud, which might be the reason for the relatively small charge transfer. The 2D imaging results also show that dart leaders may transform into dart-stepped leaders after a long time interval between successive strokes.

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“…In the past several decades, the main features of intracloud (IC) flashes and the incloud processes during cloud-to-ground (CG) flashes were resolved by the development of radio-based lightning mapping arrays operating at either high frequency/very high frequency (HF/VHF) [e.g., Proctor, 1981;Proctor et al, 1988;Mazur, 1989;Rhodes et al, 1994;Shao and Krehbiel, 1996;Rison et al, 1999;Kawasaki et al, 2000;Dong et al, 2002;Qiu et al, 2009;Zhang et al, 2010;Liu et al, 2012;Stock et al, 2014;Sun et al, 2014] or low frequency (LF) [e.g., Betz et al, 2004;Marshall et al, 2013;Bitzer et al, 2013;Karunarathne et al, 2013;Lyu et al, 2014;Yoshida et al, 2014;Wu et al, 2015;Wang et al, 2016]. A normal positive IC flash often starts with an initial negative leader that creates an upward channel bridging the negative and positive charge layers then horizontally extends into the two layers.…”

Section: Introductionmentioning

confidence: 99%

Imaging lightning intracloud initial stepped leaders by low‐frequency interferometric lightning mapping array

Lyu

Cummer

et al. 2016

Geophysical Research Letters

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By comparing the source position of pulses during initial leaders and the paths of subsequent dart leaders from typical bilevel intracloud (IC) flashes, we demonstrate a new method to image the detailed three‐dimensional (3‐D) structure and stepping dynamics of IC initial leaders. Using this approach, we show that nearly half of the initial breakdown pulses are not involved in the main channel extension but instead originate in nonpropagating branches. The primary upward but significantly tilted initial leader channels propagated with measured mean/median 3‐D step length of 295/265 m and mean/median step interval of 1.05/0.6 ms. The structure and dynamics of IC initial upward negative leaders are distinct from those of highly branched cloud‐to‐ground downward negative leaders. We suggest that the tilted initial leader channel and electric field could affect the observation on leader‐associated high‐energy radiation phenomena, such as the position‐dependent observation of terrestrial gamma ray flashes from space‐based detectors.

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Broadband and narrowband RF interferometers for lightning observations

Cited by 48 publications

References 9 publications

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

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

Characteristics of a rocket‐triggered lightning flash with large stroke number and the associated leader propagation

Imaging lightning intracloud initial stepped leaders by low‐frequency interferometric lightning mapping array

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