A1 Refereed original research article in a scientific journal
Relationships between energetic storm particle events and interplanetary shocks driven by full and partial halo coronal mass ejections
Authors: Ameri Dheyaa, Valtonen Eino, Al-Sawad Amjad, Vainio Rami
Publisher: ELSEVIER SCI LTD
Publication year: 2023
Journal: Advances in Space Research
Journal name in source: ADVANCES IN SPACE RESEARCH
Journal acronym: ADV SPACE RES
Volume: 71
Issue: 5
First page : 2521
Last page: 2533
Number of pages: 13
ISSN: 0273-1177
DOI: https://doi.org/10.1016/j.asr.2022.12.014
Web address : https://doi.org/10.1016/j.asr.2022.12.014
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/178876422
We have analysed energetic storm particle (ESP) events in 116 interplanetary (IP) shocks driven by front-side full and partial halo coronal mass ejections (CMEs) with speeds >400 kms-1during the years 1996-2015. We investigated the occurrence and relationships of ESP events with several parameters describing the IP shocks, and the associated CMEs, type II radio bursts, and solar energetic par-ticle (SEP) events. Most of the shocks (57%) were associated with an ESP event at proton energies >1 MeV. The shock transit speeds from the Sun to 1 AU of the shocks associated with an ESP event were significantly greater than those of the shocks without an ESP event, and best distinguished these two groups of shocks from each other. The occurrence and maximum intensity of the ESP events also had the strongest dependence on the shock transit speed compared to the other parameters investigated. The cor-relation coefficient between ESP peak intensities and shock transit speeds was highest (0.73 +/- 0.04) at 6.2 MeV. Weaker dependences were found on the shock speed at 1 AU, Alfve acute accent nic and magnetosonic Mach numbers, shock compression ratio, and CME speed. On aver-age all these parameters were significantly different for shocks capable to accelerate ESPs compared to shocks not associated with ESPs, while the differences in the shock normal angle and in the width and longitude of the CMEs were insignificant. The CME-driven shocks producing energetic decametric-hectometric (DH) type II radio bursts and high-intensity SEP events proved to produce also more frequently ESP events with larger particle flux enhancements than other shocks. Together with the shock transit speed, the characteristics of solar DH type II radio bursts and SEP events play an important role in the occurrence and maximum inten-sity of ESP events at 1 AU.(c) 2022 COSPAR. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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