University of Oulu

Poluianov, Stepan; Usoskin, Ilya; Mishev, Alexander; Smart, Don; Shea, Margaret 2017 Revisited definition of GLE. 35th international cosmic ray conference, ICRC2017, The astroparticle physics conference. 12-20 July 2017, Bexco, Busan, Korea, PoS(ICRC2017)125,

Revisited definition of GLE

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Author: Poluianov, Stepan1,2; Usoskin, Ilya1,2; Mishev, Alexander1;
Organizations: 1Space Climate Research Unit, University of Oulu, Finland
2Sodankylä Geophysical Observatory, University of Oulu, Finland
3SSSRC, Nashua, NH, USA
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.3 MB)
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Language: English
Published: Sissa, 2017
Publish Date: 2017-11-01


The worldwide network of neutron monitors (NMs) includes two stations, South Pole (SOPO/B) and Dome C (DOMC/B), which are exceptionally sensitive to solar energetic particles. Their locations on the high Antarctic plateau make them favorable for detection of low-energy particles because of the low geomagnetic rigidity cutoff and the thin atmosphere above. This pair of cosmic ray stations is able to register relatively weak solar energetic particle events, which would not have been detected by the NM network otherwise. Since DOMC/B station is in operation only since 2015, now the NM network is more sensitive to a SEP event than ever before. Considering such weak events as the "official" ground-level enhancements (GLEs) may break the homogeneity of the GLE definition and cause an observational bias in studies based on the GLE occurrence rate over decades.

In order to keep the "official" GLE list homogeneous, we propose to slightly modify the conventional definition of a GLE, which refers to a statistically significant enhancement of the count rate of at least two differently located neutron monitors over the background. The proposed change is as follows: "... at least two neutron monitors, one of which is located near the sea level". We also propose an introduction of a new class of SEP events called sub-GLE to identify the events registered by high-elevation polar NMs but not satisfying the revised definition of a GLE.

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Series: POS. Proceedings of science
ISSN: 1824-8039
ISSN-E: 1824-8039
ISSN-L: 1824-8039
Article number: 125
Host publication: 35th international cosmic ray conference, ICRC2017, The astroparticle physics conference. 12-20 July 2017, Bexco, Busan, Korea
Conference: International Cosmic Ray Conference
Type of Publication: B3 Article in conference proceedings
Field of Science: 115 Astronomy and space science
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).