Implications of Multiple Corona Bursts in Lightning Processes for Radio Frequency Interferometer Observations

Liu, Ningyu; Scholten, Olaf; Dwyer, J. R.; Hare, B. M.; Sterpka, C.; Tilles, J.; Lind, Frank D.

doi:10.1029/2021gl097367

Cited by 6 publications

(7 citation statements)

References 32 publications

(71 reference statements)

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“…In closing, we comment on the recent study by N. Liu, Scholten, Dwyer, et al. (2022), who showed that short‐baseline, centroid‐detecting INTFs would produce artificially fast propagation speeds between successive pairs of localized sources that are separated both spatially and temporally. This would be due to the sources being spatially unresolved by the short‐baselines of the INTF, and by the centroid of the sources rapidly switching from source A to source B partway between their locations and times of occurrence.…”

Section: Summary and Discussionmentioning

confidence: 82%

“…This is due to the VHF radiation during the NBEs being produced by a single localized source that propagates continuously with time, as seen in Figure 1, rather than a pair of discrete sources with intervening lulls in the VHF radiation, as assumed in Figure 2 of N. Liu, Scholten, Dwyer, et al. (2022). More importantly, while the sferics of IBPs are more complex than for NBEs, and exhibit several pairs of impulsive sub‐pulses associated with corona bursts, the received VHF radiation signals have excellent temporal resolution and, like NBEs, show that the VHF radiation is continuously strong and fast during the entirety of the IBPs.…”

Section: Summary and Discussionmentioning

confidence: 99%

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Analysis of Narrow Bipolar Events Using Mode Decomposition Methods

Senay,

Krehbiel,

da Silva

et al. 2023

JGR Atmospheres

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Multi‐resolution analysis methods can reveal the underlying physical dynamics of nonstationary signals, such as those from lightning. In this paper we demonstrate the application of two multi‐resolution analysis methods: Ensemble Empirical Mode Decomposition (EEMD) and Variational Mode Decomposition (VMD) in a comparative way in the analysis of electric field change waveforms from lightning. EEMD and VMD decompose signals into a set of Intrinsic Mode Functions (IMFs). The IMFs can be combined using distance and divergence metrics to obtain noise reduction or to obtain new waveforms that isolate the physical processes of interest while removing irrelevant components of the original signal. We apply the EEMD and VMD methods to the observations of three close Narrow Bipolar Events (NBEs) that were reported by Rison et al. (2016, https://doi.org/10.1038/ncomms10721). The ΔE observations reveal the occurrence of complex oscillatory processes after the main NBE sferic. We show that both EEMD and VMD are able to isolate the oscillations from the main NBE, with VMD being more effective of the two methods since it requires the least user supervision. The oscillations are found to begin at the end of the NBEs' downward fast positive breakdown, and appear to be produced by a half‐wavelength standing wave within a weakly‐conducting resonant ionization cavity left behind in the wake of the streamer‐based NBE event. Additional analysis shows that one of the NBEs was likely initiated by an energetic cosmic ray shower, and also corrects a misinterpretation in the literature that fast breakdown is an artifact of NBE‐like events in interferometer observations.

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Section: Summary and Discussionmentioning

confidence: 82%

Section: Summary and Discussionmentioning

confidence: 99%

Analysis of Narrow Bipolar Events Using Mode Decomposition Methods

Senay,

Krehbiel,

da Silva

et al. 2023

JGR Atmospheres

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“…Recent studies indicate that the fast breakdowns of NBEs sometimes contain secondary fast breakdowns along the previous path (Attanasio et al, 2021;Rison et al, 2016;Tilles et al, 2019;. Most recent observations from the LOw Frequency ARray (LOFAR) also indicate that multiple, spatially distributed corona bursts can occur in lightning processes with a timescale of 10 µs (N. Liu et al, 2022). The feature of secondary peaks and oscillations might be a fundamental property in NBE radio waveforms (Leal et al, 2019).…”

Section: Resultsmentioning

confidence: 99%

Different types of corona discharges associated with high-altitude positive Narrow Bipolar Events nearby cloud top

Luque

Gordillo‐Vázquez

et al. 2022

Preprint

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Single-and multi-pulse blue corona discharges are frequently observed in thunderstorm clouds. Although we know they often correlate with Narrow Bipolar Events (NBEs) in Very Low Frequency/Low Frequency (VLF/LF) radio signals, their physics is not well understood. Here, we report a detailed analysis of different types of blue corona discharges observed by the Atmosphere-Space Interactions Monitor (ASIM) during an overpass of a thundercloud cell nearby Malaysia. Both single-and multi-pulse blue corona discharges were associated with positive NBEs at the top of the cloud, reaching about 18 km altitude. We find that the primary pulses of multi-pulse discharges have weaker current moments than the single-pulse discharges, suggesting that the multi-pulse discharges either have shorter vertical channels or have weaker currents than the single-pulse discharges. The subsequent pulse trains of the multi-pulse discharges delayed some milliseconds are likely from horizontally oriented electrical discharges, but some NBEs, correlated with both single-and multi-pulse discharges, include small-amplitude oscillations within a few microseconds inside their waveforms, which are unresolved in the optical observation and yet to be understood. Furthermore, by jointly analyzing the optical and radio observations, we estimate the photon free mean path at the cloud top to be ˜6 m.

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“…Recent studies indicate that the fast breakdowns of NBEs sometimes contain secondary fast breakdowns along the previous path (Attanasio et al., 2021; Li, Luque, Gordillo‐Vázquez et al., 2022; Rison et al., 2016; Tilles et al., 2019). Most recent observations from the LOw Frequency ARray (LOFAR) also indicate that multiple, spatially distributed corona bursts can occur in lightning processes with a timescale of 10 µs (N. Liu et al., 2022). The feature of secondary peaks and the microsecond‐scale oscillations might be a fundamental property in NBE radio waveforms (Hamlin et al., 2007; Karunarathne et al., 2015; Leal & Rakov, 2019; Nag & Rakov, 2009).…”

Section: Discussion and Summarymentioning

confidence: 99%