New method of assessment of the integral fluence of solar energetic (> 1 GV rigidity) particles from neutron monitor data
|Author:||Koldobskiy, Sergey A.1,2; Kovaltsov, Gennady A.3; Mishev, Alexander L.1,4;|
1Space Climate Research Unit, University of Oulu, Finland
2National Research Nuclear University MEPhI, Moscow, Russia
3Ioffe Physical-Technical Institute, St. Petersburg, Russia
4Sodankylä Geophysical Observatory, University of Oulu, Finland
|Online Access:||PDF Full Text (PDF, 0.9 MB)|
|Persistent link:|| http://urn.fi/urn:nbn:fi-fe2019080723675
|Publish Date:|| 2019-08-07
A new method to reconstruct the high-rigidity part (≥ 1 GV) of the spectral fluence of solar energetic particles (SEP) for GLE events, based on the world-wide neutron monitor (NM) network data, is presented. The method is based on the effective rigidity Reff and scaling factor Keff. In contrast to many other methods based on derivation of the best-fit parameters of a prescribed spectral shape, it provides a true non-parametric (viz. free of a priori assumptions on the exact spectrum) estimate of fluence. We reconstructed the SEP fluences for two recent GLE events, #69 (20 Jan. 2005) and #71 (17 May 2012), using four NM yield functions: (CD00 — Clem and Dorman in Space Sci. Rev.93, 335, 2000), (CM12 — Caballero-Lopez and Moraal in J. Geophys. Res.117, A12103, 2012), (Mi13 — Mishev, Usoskin, and Kovaltsov in J. Geophys. Res.118, 2783, 2013), and (Ma16 — Mangeard et al. in J. Geophys. Res.121, 7435, 2016b). The results were compared with full reconstructions and direct measurements by the PAMELA instrument. While reconstructions based on Mi13 and CM12 yield functions are consistent with the measurements, those based on CD00 and Ma16 ones underestimate the fluence by a factor of 2 – 3. It is also shown that the often used power-law approximation of the high-energy tail of SEP spectrum does not properly describe the GLE spectrum in the NM-energy range. Therefore, the earlier estimates of GLE integral fluences need to be revised.
|Type of Publication:||
A1 Journal article – refereed
|Field of Science:||
115 Astronomy and space science
Open access funding provided by University of Oulu including Oulu University Hospital. Data of GLE recorded by NMs were obtained from the International GLE database http://gle.oulu.fi and NMDB database ( www.nmdb.eu , founded under the European Union’s FP7 programme, contract no. 213007). PIs and teams of all the ground-based neutron monitors whose data were used here, are gratefully acknowledged. This work was partially supported by the ReSoLVE Centre of Excellence (project no. 307411) and HEAIM Project (no. 314982 and no. 316223) of Academy of Finland, by the grant no. MK-6160.2018.2 of the President of the Russian Federation and MEPhI Academic Excellence Project (contract 02.a03.21.0005).
|EU Grant Number:||
(213007) NMDB - Real-Time database for high resolution Neutron Monitor measurements
|Academy of Finland Grant Number:||
307411 (Academy of Finland Funding decision)
314982 (Academy of Finland Funding decision)
316223 (Academy of Finland Funding decision)
© The Author(s) 2019. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.