3 years ago

Catalogue of > 55 ${>}\,55$ MeV Wide-longitude Solar Proton Events Observed by SOHO, ACE, and the STEREOs at ≈ 1 ${\approx}\,1$ AU During 2009 – 2016

Rami Vainio, Bernd Heber, Athanasios Papaioannou, Miikka Paassilta, Nina Dresing, Eino Valtonen

Abstract

Based on energetic particle observations made at \({\approx}\,1\)  AU, we present a catalogue of 46 wide-longitude ( \({>}\,45^{\circ}\) ) solar energetic particle (SEP) events detected at multiple locations during 2009 – 2016. The particle kinetic energies of interest were chosen as \({>}\,55\)  MeV for protons and 0.18 – 0.31 MeV for electrons. We make use of proton data from the Solar and Heliospheric Observatory/Energetic and Relativistic Nuclei and Electron Experiment (SOHO/ERNE) and the Solar Terrestrial Relations Observatory/High Energy Telescopes (STEREO/HET), together with electron data from the Advanced Composition Explorer/Electron, Proton, and Alpha Monitor (ACE/EPAM) and the STEREO/Solar Electron and Proton Telescopes (SEPT). We consider soft X-ray data from the Geostationary Operational Environmental Satellites (GOES) and coronal mass ejection (CME) observations made with the SOHO/Large Angle and Spectrometric Coronagraph (LASCO) and STEREO/Coronagraphs 1 and 2 (COR1, COR2) to establish the probable associations between SEP events and the related solar phenomena. Event onset times and peak intensities are determined; velocity dispersion analysis (VDA) and time-shifting analysis (TSA) are performed for protons; TSA is performed for electrons. In our event sample, there is a tendency for the highest peak intensities to occur when the observer is magnetically connected to solar regions west of the flare. Our estimates for the mean event width, derived as the standard deviation of a Gaussian curve modelling the SEP intensities (protons \({\approx}\,44^{\circ}\) , electrons \({\approx}\,50^{\circ}\) ), largely agree with previous results for lower-energy SEPs. SEP release times with respect to event flares, as well as the event rise times, show no simple dependence on the observer’s connection angle, suggesting that the source region extent and dominant particle acceleration and transport mechanisms are important in defining these characteristics of an event. There is no marked difference between the speed distributions of the CMEs related to wide events and the CMEs related to all near-Earth SEP events of similar energy range from the same time period.

Publisher URL: https://link.springer.com/article/10.1007/s11207-018-1284-7

DOI: 10.1007/s11207-018-1284-7

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