University of Oulu

Mishev, A., Usoskin, I., & Kocharov, L. (2021, June 24). Halloween GLEs on October-November 2003, spectra and angular distribution: Revised results. Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021). 37th International Cosmic Ray Conference.

Halloween GLEs on October–November 2003, spectra and angular distribution : revised results

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Author: Mishev, Alexander1,2; Usoskin, Ilya1,2; Kocharov, Leon1
Organizations: 1Sodankylä Geophysical Observatory,University of Oulu, Finland
2Space Physics and Astronomy Research Unit,University of Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.7 MB)
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Language: English
Published: Sissa, 2021
Publish Date: 2021-08-17


A precise study of solar energetic particles provides an important basis to understand their acceleration and propagation in the interplanetary space. A specific interest is paid to solar protons possessing energy high enough, so that they can induce an atmospheric cascade in the Earth’s atmosphere, whose secondary particles reach the ground, eventually being registered by ground-based detectors e.g. neutron monitors. This particular class of events is called ground-level enhancements (GLEs). The solar cycle 23 provided several strong GLEs. The first strong GLE event of the cycle was observed on 14 July 2000 (the Bastille day event), while the last was observed on 13 December 2006. In addition, the period of late October — early November 2003 was characterized by strong cosmic ray variability and a sequence of three GLEs (the so-called Halloween GLEs) was registered, which is the focus of this study. Here, we performed a precise analysis of neutron monitor records and derived the spectral and angular characteristics of the solar energetic particles during the Halloween GLEs. We modeled the particle propagation in the Earth’s magnetosphere and atmosphere using a verified NM yield function computed at several altitudes above the sea level. The solar protons spectra and pitch angle distributions were obtained in their dynamical development throughout the events. We briefly discuss the revealed features of the Halloween events.

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Series: POS. Proceedings of science
ISSN: 1824-8039
ISSN-E: 1824-8039
ISSN-L: 1824-8039
Volume: 395
Article number: 1261
DOI: 10.22323/1.395.1261
Host publication: Proceedings of 37th International Cosmic Ray Conference (ICRC2021)
Conference: International Cosmic Ray Conference
Type of Publication: B3 Article in conference proceedings
Field of Science: 115 Astronomy and space science
Funding: We acknowledge the Academy of Finland (project 330064 QUASARE and 321882 ESPERA).
Academy of Finland Grant Number: 330064
Detailed Information: 330064 (Academy of Finland Funding decision)
321882 (Academy of Finland Funding decision)
Copyright information: © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).