University of Oulu

Usoskin, I., Koldobskiy, S., Kovaltsov, G. A., Gil, A., Usoskina, I., Willamo, T., & Ibragimov, A. (2020). Revised GLE database: Fluences of solar energetic particles as measured by the neutron-monitor network since 1956. Astronomy & Astrophysics, 640, A17.

Revised GLE database : fluences of solar energetic particles as measured by the neutron-monitor network since 1956⋆

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Author: Usoskin, I.1,2; Koldobskiy, S.3; Kovaltsov, G. A.4;
Organizations: 1Space Physics and Astronomy Research Unit, University of Oulu, Oulu, Finland
2Sodankylä Geophysical Observatory, University of Oulu, Oulu, Finland
3National Research Nuclear University MEPhI, Moscow, Russia
4A.F. Ioffe Physical-Technical Institute of Russian Academy of Sciences, St. Petersburg, Russia
5Siedlce University, Faculty of Exact and Natural Sciences, Institute of Mathematics, Siedlce, Poland
6Space Research Centre of Polish Academy of Sciences, Warsaw, Poland
7Department of Physics, University of Helsinki, Helsinki, Finland
8Independent Researcher, Helsinki, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 4.7 MB)
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Language: English
Published: EDP Sciences, 2020
Publish Date: 2020-08-14


Aims: Continuous measurements of ground-based neutron monitors (NMs) form the main data source for studying high-energy high-intensity solar energetic particle (SEP) events that are called ground-level enhancements (GLEs). All available data are collected in the International GLE Database (IGLED), which provides formal NM count-rate increases above the constant pre-increase level which is due to galactic cosmic rays (GCR). This data set is used to reconstruct the energy spectra of GLE events. However, the assumption of a constant GCR background level throughout GLE events is often invalid. Here we thoroughly revise the IGLED and provide a data set of detrended NM count-rate increases that accounts for the variable GCR background.

Methods: The formal GLE count-rate increases were corrected for the variable GCR background, which may vary significantly during GLE events. The corresponding integral omnidirectional fluences of SEPs were reconstructed for all GLEs with sufficient strength from the detrended data using the effective rigidity method.

Results: The database of the detrended NM count rate is revised for GLE events since 1956. Integral omnidirectional fluences were estimated for 58 GLE events and parametrised for 52 sufficiently strong events using the modified Ellison-Ramaty spectral shape.

Conclusions: The IGLED was revised to account for the variable GCR background. Integral omnidirectional fluences reconstructed for most of GLE events were added to IGLED. This forms the basis for more precise studies of parameters of SEP events and thus for solar and space physics.

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Series: Astronomy and astrophysics
ISSN: 0004-6361
ISSN-E: 1432-0746
ISSN-L: 0004-6361
Volume: 640
Article number: A17
DOI: 10.1051/0004-6361/202038272
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: DOMC/DOMB experiment is supported by IPEV and PNRA (LTCPAA project PNRA 2015/AC3). This work was partially supported by the Academy of Finland (projects No. 321882 ESPERA and No. 304435 CRIPA-X), MEPhI Academic Excellence Project (contract 02.a03.21.0005) and the Polish National Science Centre (project no. 2016/22/E/HS5/00406. A part of this work (analysis of GLE spectra) was partly supported by the RSF grant No 20-67-46016.
Academy of Finland Grant Number: 321882
Detailed Information: 321882 (Academy of Finland Funding decision)
304435 (Academy of Finland Funding decision)
Copyright information: © ESO 2020. Published in this repository with the kind permission of the publisher.