SEPServer catalogues of solar energetic particle events at 1 AU based on STEREO recordings: 2007–2012

Abstract

The Solar Terrestrial Relations Observatory (STEREO) recordings provide an unprecedented opportunity to study the evolution of solar energetic particle (SEP) events from different observation points in the heliosphere, allowing one to identify the effects of the properties of the interplanetary magnetic field (IMF) and solar wind structures on the interplanetary transport and acceleration of SEPs. Two catalogues based on STEREO recordings, have been compiled as a part of the SEPServer project, a three-year collaborative effort of eleven European partners funded under the Seventh Framework Programme of the European Union (FP7/SPACE). In particular, two instruments on board STEREO have been used to identify all SEP events observed within the descending phase of solar cycle 23 and the rising phase of solar cycle 24 from 2007 to 2012, namely: the Low Energy Telescope (LET) and the Solar Electron Proton Telescope (SEPT). A scan of STEREO/LET protons within the energy range 6-10 MeV has been performed for each of the two STEREO spacecraft. We have tracked all enhancements that have been observed above the background level of this particular channel and cross-checked with available lists of interplanetary coronal mass ejections (ICMEs), stream interaction regions (SIRs), and shocks, as well as with the reported events in literature. Furthermore, parallel scanning of the STEREO near relativistic electrons has been performed in order to pinpoint the presence (or absence) of an electron event in the energy range of 55-85 keV, for all of the aforementioned proton events included in our lists. We provide the onset and peak time as well as the peak value of all events for both protons and electrons, the relevant solar associations in terms of electromagnetic emissions, soft and hard X-rays (SXRs and HXRs). Finally, a subset of events with clear recordings at both STEREO spacecraft is presented together with the parent solar events of these multispacecraft SEP events.

North/South Hemispheric Periodicities in the ${>}\,25\mbox{ MeV}$ Solar Proton Event Rate During the Rising and Peak Phases of Solar Cycle 24

“…In particular, Rieger et al (1984) recognized a ≈154 day periodicity in X-ray flares during Cycle 21. Such "near-Rieger" periodicities have also been reported by, for example: Lean (1990) (who identified periods of ≈ 130-185 days in a survey of multiple sunspot cycles); Bai and Cliver (1990) (in proton-producing flares); Gonzalez et al (1993) (geomagnetic activity); Cane, Richardson, and von Rosenvinge (1998) (IMF and 25 MeV proton intensity in Cycle 21, including event clustering similar to that reported here); Dalla et al (2001) (SEP events in Cycle 23); Hill, Hamilton, and Krimigis (2001) (anomalous cosmic ray intensity in the outer heliosphere); Ballester, Oliver, and Carbonell (2004) (photospheric magnetic field); Richardson and Cane (2005) (SEP intensity, ICME and geomagnetic storm sudden commencement rate, hemispheric sunspot numbers, IMF); Lou et al (2003) and Lara et al (2008) (coronal mass ejections); and Lobzin, Cairns, and Robinson (2012) (solar type III radio bursts in Cycle 23). As discussed by several of these papers, in particular Lean (1990), these periodicities vary in strength and period both from cycle to cycle and within a given cycle.…”

“…Richardson et al (2014) noted that, during the rise phase of Solar Cycle 24 (which commenced in December 2008 based on the smoothed sunspot number), clusters of SEP events occurred at intervals of ≈ 6-7 months, separated by periods with few SEPs. They suggested that this phenomenon might be related to the periodicities in SEP occurrence and other solar parameters reported in previous solar cycles (e.g., Rieger et al, 1984;Cane, Richardson, and von Rosenvinge, 1998;Dalla et al, 2001;Richardson and Cane, 2005;and references therein). Figure 1 is an updated version of Figure 1 of Richardson et al (2014) which illustrates this point.…”

“…It is also apparent in Figure 1 that the vast majority of the SEP events occurred in and after 2011, when the STEREO spacecraft were located above the far side of the Sun as viewed from Earth. Hence, the STEREOs and spacecraft at Earth together provided an extended view in longitude at ≈ 1 AU of these SEP events (e.g., Rouillard et al, 2011;Dresing et al, 2012;Lario et al, 2013;Wiedenbeck et al, 2013;Cohen et al, 2014;Richardson et al, 2014, Papaioannou et al, 2014Lario et al, 2014;Gómez-Herrero et al, 2015;von Rosenvinge et al, 2015;Lario et al, 2016).…”

The Solar Energetic Particle Event of 2010 August 14: Connectivity with the Solar Source Inferred from Multiple Spacecraft Observations and Modeling

“…One is to define the onset as the time when the particle intensity rises above the pre-event average background by a certain factor expressed in units of the statistical error of the pre-event counting rate (e.g., Papaioannou et al 2014) or more qualitatively, by visual inspection of suitably scaled intensity-time plots. Another procedure is to use the cumulative sum (CUSUM) method to calculate the normalized time-integrated excess of the counting rate above the background or pre-event intensity level (Torsti et al 1998).…”

Longitudinal Properties of a Widespread Solar Energetic Particle Event on 2014 February 25: Evolution of the Associated Cme Shock

“…The combination of observations performed simultaneously by a number of spacecraft located at distant heliospheric locations is the primary tool to investigate the spatial distribution of solar energetic particle (SEP) events (e.g., McKibben 1972;McGuire et al 1983;Kallenrode et al 1992;Reames et al 1996;Lario et al 2000Lario et al , 2003Lario et al , 2006Lario et al , 2013McKibben et al 2003;Wibberenz & Cane 2006;Dresing et al 2012Dresing et al , 2014Rouillard et al 2012;Park et al 2013;Wiedenbeck et al 2013;Papaioannou et al 2014;Richardson et al 2014;Gómez-Herrero et al 2015). The most intense SEP events, originally associated with gradual solar flares (i.e., flares with time durations of the 1-8 Å soft X-ray (SXR) emission at 0.1 of the peak intensity longer than 1 hr; cf.…”