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14 results on '"Koronczay, Dávid"'

1. Relation Between Sprites and Whistlers Based on AWDANET and WWLLN Data

Author

Malkin, Evgeniy, Kazakov, Evgeniy, Cherneva, Nina, Lichtenberger, Janos, Sannikov, Dmitriy, Koronczay, David, Bezaeva, Natalia S., Series Editor, Gomes Coe, Heloisa Helena, Series Editor, Nawaz, Muhammad Farrakh, Series Editor, Dmitriev, Alexei, editor, Lichtenberger, Janos, editor, Mandrikova, Oksana, editor, and Nahayo, Emmanuel, editor

Published
2023
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2. The Source Regions of Whistlers

Author

Koronczay, Dávid, Lichtenberger, János, Clilverd, Mark A., Rodger, Craig J., Lotz, Stefan I., Sannikov, Dmitry V., Cherneva, Nina V., Raita, Tero, Darrouzet, Fabien, and Moore, Robert C.

Subjects
Physics - Space Physics
Abstract

We present a new method for identifying the source regions of lightning generated whistlers observed at a fixed location. In addition to the spatial distribution of causative lightning discharges, we calculate the transmission ratio of lightning discharges into ground detectable whistlers as a function of location. Our method relies on the time of the whistlers and the time and source location of spherics from a global lightning database. We apply this method to whistlers recorded at fifteen ground based stations in the AWDANet (Automatic Whistler Detector and Analyzer Network) operating between 2007-2018 and to located lightning strokes from the WWLLN (World Wide Lightning Location Network) database. We present the obtained maps of causative lightning and transmission ratios. Our results show that the source region of whistlers corresponding to each ground station is around the magnetic conjugate point of the respective station. The size of the source region is typically less than 2000 km in radius with a small fraction of sources extending to up to 3500 km. The transmission ratio is maximal at the conjugate point and decreases with increasing distance from it. This conforms to the theory that whistlers detected on the ground propagated in a ducted mode through the plasmasphere and thus the lightning strokes of their causative spherics must cluster around the footprint of the ducts in the other hemisphere. Our method applied resolves the whistler excitation region mystery that resulted from correlation-based analysis methods, concerning the source region of whistlers detected in Dunedin, New Zealand., Comment: 22 pages, 10 figures, submitted to Journal of Geophysical Research, Space Physics

Published
2019
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3. VLF transmitters as tools for monitoring the plasmasphere

Author

Koronczay, David, Lichtenberger, Janos, Juhasz, Lilla, Steinbach, Peter, and Hospodarsky, George

Subjects
Physics - Space Physics, Astrophysics - Earth and Planetary Astrophysics
Abstract

Continuous burst mode VLF measurements were recorded on the RBSP/Van Allen Probes satellites and are analyzed to detect pulses from the Russian Alpha (RSDN-20) ground-based navigational system. Based on the wave characteristics of these pulses and on the position of the spacecraft, the signals propagated mostly in ducted mode in the plasmasphere. Knowledge of the propagation path allowed us to carry out a monochromatic wave propagation inversion to obtain plasmaspheric electron densities. We compared the obtained densities with independent in-situ measurements on the spacecraft. The results show good agreement, validating our inversion process. This contributes to validating the field-aligned density profile model routinely used in the inversion of whistlers detected on the ground. Furthermore, our method can provide electron densities at regimes where no alternative measurements are available on the spacecraft. This raises the possibility of using this method as an additional tool to measure and monitor plasmaspheric electron densities., Comment: 21 pages, 5 figures, accepted by Journal of Geophysical Research

Published
2018
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4. Monitoring space weather: using automated, accurate neural network based whistler segmentation for whistler inversion

Author

Pataki, Bálint Ármin, Lichtenberger, János, Clilverd, Mark, Máthé, Gergely, Steinbach, Péter, Pásztor, Szilárd, Murár‐Juhász, Lilla, Koronczay, Dávid, Ferencz, Orsolya, Csabai, István, Pataki, Bálint Ármin, Lichtenberger, János, Clilverd, Mark, Máthé, Gergely, Steinbach, Péter, Pásztor, Szilárd, Murár‐Juhász, Lilla, Koronczay, Dávid, Ferencz, Orsolya, and Csabai, István

Abstract

It is challenging, yet important, to measure the - ever-changing - cold electron density in the plasmasphere. The cold electron density inside and outside of the plasmapause is a key parameter for radiation belt dynamics. One indirect measurement is through finding the velocity dispersion relation exhibited by lightning induced whistlers. The main difficulty of the method comes from low signal-to-noise ratios for most of the ground-based whistler components. To provide accurate electron density and L-shell measurements, whistler components need to be detectable in the noisy background, and their characteristics need to be reliably determined. For this reason precise segmentation is needed on a spectrogram image. Here we present a fully automated way to perform such an image segmentation by leveraging the power of convolutional neural networks, a state-of-the-art method for computer vision tasks. Testing the proposed method against a manually, and semi-manually segmented whistler dataset achieved <10% relative electron density prediction error for 80% of the segmented whistler traces, while for the L-shell, the relative error is <5% for 90% of the cases. By segmenting more than 1 million additional real whistler traces from Rothera station Antarctica, logged over 9 years, seasonal changes in the average electron density were found. The variations match previously published findings, and confirm the capabilities of the image segmentation technique.

Published
2022

6. Measurements of atmospheric electricity in the Széchenyi István Geophysical Observatory, Hungary

Author

Bór, József, Sátori, Gabriella, Barta, Veronika, Szabóné-André, Karolina, Szendrői, Judit, Wesztergom, Viktor, Bozóki, Tamás, Buzás, Attila, and Koronczay, Dávid

Abstract

The Széchenyi István Geophysical Observatory, also known as the Nagycenk Geophysical Observatory (NCK), was established in 1957. It has been the only measurement site in Hungary where observations of various parameters of the atmospheric global electric circuit are made in the framework of organized research under the umbrella of the Hungarian Academy of Sciences (MTA). Measurements of the atmospheric electrical potential gradient (PG) and Schumann resonances (SRs) running quasi-continuously in the observatory for decades provide an invaluable source of information for geophysical research. This paper gives an overview on the history of the observatory and particularly on various atmospheric electricity (AE) measurements on-site to commemorate the efforts and excellence of the people who served atmospheric sciences by dedicating their lives to obtaining high-quality, reliable data and scientific achievements at the highest possible level.

Published
2020

10. The Source Regions of Whistlers

Author

Koronczay, Dávid, primary, Lichtenberger, János, additional, Clilverd, Mark A., additional, Rodger, Craig J., additional, Lotz, Stefan I., additional, Sannikov, Dmitry V., additional, Cherneva, Nina V., additional, Raita, Tero, additional, Darrouzet, Fabien, additional, Ranvier, Sylvain, additional, and Moore, Robert C., additional

Published
2019
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13. Investigation of the Ionospheric Absorption Response to Flare Events during Solar Cycle 23 using Ionosonde and DEMETER VLF Observations.

Author

Barta, Veronika, Koronczay, Dávid, Berényi, Kitti, Kis, Árpád, Sátori, Gabriella, and Williams, Earle

Subjects
*SOLAR flares, *SOLAR cycle, *RADIO waves, *ZENITH distance, *ABSORPTION, *ARTIFICIAL satellites, *TIME series analysis
Abstract

Systematic analysis of ionosopheric parameters measured at mid and low latitudes was performed to understand the ionospheric response to solar flares. The lowest recorded ionosonde echo, the minimum frequency (fmin, a qualitative proxy for the "nondeviative" radio wave absorption occurring in the D-layer), furthermore the dfmin parameter (difference between the value of fmin and the mean fmin for reference days) have been investigated. The time series of the fmin and dfmin parameters recorded at meridionally-distributed ionosonde stations in Europe and South Africa were analyzed during 8 X and M class solar flares during solar cycle 23. The solar zenith angle of the observation sites at the time of the selected flares have been also taken into account. Total and partial radio fade-out was experienced at every ionospheric stations during intense solar flares (> M6). The duration of the total radio fade-out varied between 15 and 150 min and was highly dependent on the solar zenith angle of the ionospheric stations. Furthermore, a solar zenith angle-dependent enhancement of the fmin (2-9 MHz) and dfmin (1-8 MHz) parameters was observed at almost every stations at the time of the flare events. The observed values of the fmin and dfmin parameters show an increasing trend with the enhancement of the X-ray flux. In addition, we observed attenuation/fade out of VLF signals onboard the DEMETER low Earth satellite, co-temporal with two of the solar flares, occurring on 5th and 6th December, 2006, respectively. This demonstrates a quantifiable change in transionospheric VLF absorption associated with flare events. [ABSTRACT FROM AUTHOR]

Published
2019

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