Halloween GLEs on October–November 2003, spectra and angular distribution : revised results
Mishev, Alexander; Usoskin, Ilya; Kocharov, Leon (2021-06-24)
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. https://doi.org/10.22323/1.395.1261
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https://creativecommons.org/licenses/by-nc-nd/4.0/
https://urn.fi/URN:NBN:fi-fe2021081743449
Tiivistelmä
Abstract
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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