University of Oulu

Mishev, A.L., Kocharov, L.G., Koldobskiy, S.A. et al. High-Resolution Spectral and Anisotropy Characteristics of Solar Protons During the GLE N∘73 on 28 October 2021 Derived with Neutron-Monitor Data Analysis. Sol Phys 297, 88 (2022).

High-resolution spectral and anisotropy characteristics of solar protons during the GLE N°73 on 28 October 2021 derived with neutron-monitor data analysis

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Author: Mishev, Alexander L.1,2; Kocharov, Leon G.2; Koldobskiy, Sergey A.1,2;
Organizations: 1Space Physics and Astronomy Research Unit, University of Oulu, Oulu, Finland
2Sodankylä Geophysical Observatory, University of Oulu, Oulu, Finland
3Department of Physics and Astronomy, University of Turku, Turku, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.5 MB)
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Language: English
Published: Springer Nature, 2022
Publish Date: 2022-10-05


The first ground-level enhancement of the current Solar Cycle 25 occurred on 28 October 2021. It was observed by several space-borne and ground-based instruments, specifically neutron monitors. A moderate count-rate increase over the background was observed by high-altitude polar stations on the South Pole and Dome C stations at the Antarctic plateau. Most of the neutron monitors registered only marginal count-rate increases. Using detrended records and employing a method verified by direct space-borne measurements, we derive the rigidity spectra and angular distributions of the incoming solar protons in the vicinity of Earth. For the analysis, we employed a newly computed and parameterized neutron-monitor yield function. The rigidity spectra and anisotropy of solar protons were obtained in their time evolution throughout the event. A comparison with the Solar and Heliospheric Observatory/Energetic and Relativistic Nuclei and Electron (SOHO/ENRE) experiment data is also performed. We briefly discuss the results derived from our analysis.

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Series: Solar physics
ISSN: 0038-0938
ISSN-E: 1573-093X
ISSN-L: 0038-0938
Volume: 297
Issue: 7
Article number: 88
DOI: 10.1007/s11207-022-02026-0
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: This work was supported by the Academy of Finland (projects ESPERA No. 321882, QUASARE No. 330064, and FORESAIL No. 336809), University of Oulu (Project SARPEDON). Operation of the DOMC/DOMB NM was possible due to support of the French–Italian Concordia Station (IPEV program n903 and PNRA Project LTCPAA PNRA14 00091), and the Finnish Antarctic Research Program (FINNARP). The work benefited from discussions in the framework of the International Space Science Institute International Team 441: High Energy Solar Particle Events Analysis (HEROIC). We acknowledge NMDB and all of the colleagues and PIs from the neutron-monitor stations who kindly provided the data used in this analysis, namely: Alma Ata, Apatity, Athens, Baksan, Calgary, Dome C, Dourbes, Forth Smith, Inuvik, Jang Bogo, Jungfraujoch, Kerguelen, Lomnicky Štit, Mexico City, Nain, Norilsk, Oulu, Peawanuck, Rome, Sanae, South Pole, Terre Adelie, Thule, Tixie, and Yakutsk. We thank the ACE/MAG and ACE/SWEPAM instrument teams and the ACE Science Center for providing the ACE data. SOHO is a project of international cooperation between ESA and NASA.
Academy of Finland Grant Number: 321882
Detailed Information: 321882 (Academy of Finland Funding decision)
330064 (Academy of Finland Funding decision)
Dataset Reference: The datasets generated during and/or analyzed during the current study are available on the corresponding web-pages of the space-borne instruments, while the NM records are available in the International GLE Database
Copyright information: © The Author(s) 2022. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit