X-ray Observations at Gaisberg Tower

Hettiarachchi, Pasan; Cooray, Vernon; Diendorfer, Gerhard; Pichler, Hannes; Dwyer, J. R.; Rahman, Mahbubur

doi:10.3390/atmos9010020

Cited by 12 publications

(10 citation statements)

References 34 publications

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“…(2012) with emphasis on subsequent strokes, they observed that not all leaders of the same flash produced detectable X‐rays. Due to the lower air density and consequently lower X‐ray absorption, observations of high‐energy radiation from thunderstorms were conduced at high‐altitude towers (e.g., Hettiarachchi et al., 2018; Montanyà et al., 2014) and on aircraft (e.g., Kochkin et al., 2017; Skeie et al., 2020; Smith et al., 2011). Recently, Saba et al.…”

Section: Introductionmentioning

confidence: 99%

“…A statistical study of X-ray emissions was published by Mallick et al (2012) with emphasis on subsequent strokes, they observed that not all leaders of the same flash produced detectable X-rays. Due to the lower air density and consequently lower X-ray absorption, observations of high-energy radiation from thunderstorms were conduced at high-altitude towers (e.g., Hettiarachchi et al, 2018;Montanyà et al, 2014) and on aircraft (e.g., Kochkin et al, 2017;Skeie et al, 2020;Smith et al, 2011). Recently, Saba et al (2019) measured X-ray emissions in coincidence with a dart leader using high-speed video and pointing out the role of the leader orientation in the X-ray detection.…”

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confidence: 99%

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High‐Energy Radiation From Natural Lightning Observed in Coincidence With a VHF Broadband Interferometer

et al. 2021

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This work presents the first simultaneous X‐ray measurements from natural lightning in coincidence with a very high frequency (VHF) broadband interferometer. During an observational campaign in north‐central Colombia, five intense X‐ray bursts were detected from negative stepped leaders and two X‐ray emissions from a dart leader. Thanks to the high angular and time resolution of the interferometer, it was possible to locate the origin of high‐energy radiation during the lightning leader propagation. We study the correlation with VHF pulses and the two‐dimensional speed of the leader channels. A strong temporal correspondence has been observed between the high‐energy emissions and the most intense VHF pulses, which suggests the runaway electrons as a shared mechanism. The observations show that an X‐ray burst can have multiple high‐energy sources belonging to different leader branches, that can be several hundreds of meters apart. Therefore, from a spatial point of view, not a unique origin has to be searched, but an extensive origin of the X‐ray burst should be considered. We hypothesize similar conclusions in particular for downward TGFs and maybe for TGFs in general.

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

High‐Energy Radiation From Natural Lightning Observed in Coincidence With a VHF Broadband Interferometer

et al. 2021

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“…Lightning emits X-rays. Although progress has been achieved in quantifying some properties of the lightning-leader X-ray emission in natural, rocket-triggered, and upward lightning (e.g., Moore et al, 2001, Dwyer et al, 2003, Dwyer et al, 2004, Dwyer et al, 2005, Dwyer et al, 2011Saleh et al, 2009;Yoshida et al, 2008;Howard et al, 2008, Howard et al, 2010Mallick et al, 2012;Hettiarachchi et al, 2018), it is still uncertain why not all strokes in the same flash and not all leader steps in the same stroke produce detectable X-rays. Howard et al (2010) reported observations of leader electric fields and generation of energetic radiation close to triggered lightning.…”

Section: Introductionmentioning

confidence: 99%

High‐Speed Video Observation of a Dart Leader Producing X‐rays

et al. 2019

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This work presents the first simultaneous X-ray measurement and high-speed video observation of the propagation of a lightning leader producing X-rays. As a result, the three-dimensional leader distance from the X-ray measurement and, for the first time, the conditions of the preexisting channel during the leader propagation were observed. Although four leaders in this seven-stroke flash followed the same path to ground, X-rays were only observed during the leader before the return stroke with the highest peak current. The fact that the other three leaders following the same path to ground did not produce detectable X-rays confirms the hypothesis that leader line charge density is an important factor that determines X-ray production. The fact that X-rays was recorded only when the leader tip was at a certain portion of the lightning channel confirms that the orientation of the leader plays an important role in the detection of X-rays. Plain Language SummaryIt was known that lightning can produce X-rays. However, in this study, thanks to the use of a high-speed video camera it was possible to determine when lightning produces X-rays, how far it was, how it was oriented when the detection of X-rays, and what the conditions of the preexisting channel were during the leader propagation. The observations of the present work allow for new insights, confirmation of some hypotheses, and comparison with past studies. The results presented help to understand why X-rays are sometimes detected and sometimes not. It is shown that the amount of charge transferred by the discharge plays a crucial role. This study also confirms that the orientation of the descending leader plays an important role in the detection of X-rays.

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“…Lightning detection technology has always played an important role in lightning research [1][2][3]. With the development of microelectronics and optoelectronic technology, lightning detection methods have been improved significantly since the 1970s [4][5][6][7][8][9][10][11][12][13][14][15]. Therefore, people have made breakthrough progress in understanding the distribution structure of positive and negative charge layers in thunderstorms and the discharge processes of intra-cloud flash (IC) and cloud-to-ground flash (CG) at various stages, making it possible to conduct fine research on the lightning development process [16][17][18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

The Three-Dimensional Locating of VHF Broadband Lightning Interferometers

2018

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VHF (Very High Frequency) lightning interferometers can locate and observe lightning discharges with a high time resolution. Especially the appearance of continuous interferometers makes the 2-D location of interferometers further improve in time resolution and completeness. However, there is uncertainty in the conclusion obtained by simply analyzing the 2-D locating information. Without the support of other 3-D total lightning locating networks, the 2-station interferometer becomes an option to obtain 3-D information. This paper introduces a 3-D lightning location method of a 2-station broadband interferometer, which uses the theodolite wind measurement method for reference, and gives the simulation results of the location accuracy. Finally, using the multi-baseline continuous 2-D locating method and the 3-D locating method, the locating results of one intra-cloud flash and the statistical results of the initiation heights of 61 cloud-to-ground flashes and 80 intra-cloud flashes are given. The results show that the two-station interferometer has high observation accuracy on both sides of the connection between the two sites. The locating accuracy will deteriorate as the distance between the radiation source and the two stations increases or the height decreases. The actual locating results are similar to those of the existing VHF TDOA (Time Difference of Arrival) lightning locating network.which is much higher than that of the existing TDOA locating system [29]. Although these advantages can only be fully demonstrated when the interferometer is used for azimuth-elevation 2-D direction finding, the high time resolution 2-D locating of the interferometer can be used for networking observation or in combination with another set of lightning locating system to give full play to its characteristics and describe the lightning discharge process in detail [23,30,31]. Currently, the existing lightning interferometers can be roughly divided into two types: narrow-band interferometers and wide-band interferometers, depending on the bandwidth of the received signals [6,32]. The observed performance of the two types of equipment is similar, but the broadband interferometer can record the VHF broadband radiation waveform of lightning, and can use various digital signal processing methods to optimize the locating results afterward [29,33]. Especially the continuous interferometer using high-speed Analog to Digital (A/D) data acquisition card at present has a high time resolution, a large dynamic range of signal amplitude resolution and continuous sampling recording ability, making the new interferometer able to describe the lightning discharge processes more completely [29].A single-station broadband interferometer system can only give the locating results of the radiation sources in two dimensions, with which many conclusions can be made based on the estimation. Even if the 3-D information can be estimated by combining the information provided by other synchronous observation systems [22,30,31], there is still an inconvenienc...

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X-ray Observations at Gaisberg Tower

Cited by 12 publications

References 34 publications

High‐Energy Radiation From Natural Lightning Observed in Coincidence With a VHF Broadband Interferometer

High‐Energy Radiation From Natural Lightning Observed in Coincidence With a VHF Broadband Interferometer

High‐Speed Video Observation of a Dart Leader Producing X‐rays

The Three-Dimensional Locating of VHF Broadband Lightning Interferometers

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