Solar energetic particle (SEP) events are related to flares and coronal mass ejections (CMEs). This work is a new investigation of statistical relationships between SEP peak intensities -deka-MeV protons and near-relativistic electrons -and characteristic quantities of the associated solar activity. We consider the speed of the CME and quantities describing the flare-related energy release: peak flux and fluence of soft X-ray (SXR) emission, fluence of microwave emission. The sample comprises 38 SEP events associated with strong SXR bursts (classes M and X) in the western solar hemisphere between 1997 and 2006, and where the flare-related particle acceleration is accompanied by radio bursts indicating electron escape to the interplanetary space. The main distinction of the present statistical analysis from earlier work is that besides the classical Pearson correlation coefficient the partial correlation coefficients are calculated in order to disentangle the effects of correlations between the solar parameters themselves. The classical correlation analysis shows the usual picture of correlations with broad scatter between SEP peak intensities and the different parameters of solar activity, and strong correlations between the solar activity parameters themselves. The partial correlation analysis shows that the only parameters that affect significantly the SEP intensity are the CME speed and the SXR fluence. The SXR peak flux and the microwave fluence have no additional contribution. We conclude that these findings bring statistical evidence that both flare acceleration and CME shock acceleration contribute

SEPServer is a three-year collaborative project funded by the seventh framework programme (FP7-SPACE) of the European Union. The objective of the project is to provide access to state-of-the-art observations and analysis tools for the scientific community on solar energetic particle (SEP) events and related electromagnetic (EM) emissions. The project will eventually lead to better understanding of the particle acceleration and transport processes at the Sun and in the inner heliosphere. These processes lead to SEP events that form one of the key elements of space weather. In this paper we present the first results from the systematic analysis work performed on the following datasets: SOHO/ERNE, SOHO/EPHIN, ACE/EPAM, Wind/WAVES and GOES X-rays. A catalogue of SEP events at 1 AU, with complete coverage over solar cycle 23, based on high-energy (~68-MeV) protons from SOHO/ERNE and electron recordings of the events by SOHO/EPHIN and ACE/EPAM are presented. A total of 115 energetic particle events have been identified and analysed using velocity dispersion analysis (VDA) for protons and time-shifting analysis (TSA) for electrons and protons in order to infer the SEP release times at the Sun. EM observations during the times of the SEP event onset have been gathered and compared to the release time estimates of particles. Data from those events that occurred during the European day-time, i.e., those that also have observations from ground-based observatories included in SEPServer, are listed and a preliminary analysis of their associations is presented. We find that VDA results for protons can be a useful tool for the analysis of proton release times, but if the derived proton path length is out of a range of 1 AU < s [ 3 AU, the result of the analysis may be compromised, as indicated by the anti-correlation of the derived path length and release time delay from the associated X-ray flare. The average path length derived from VDA is about 1.9 times the nominal length of the spiral magnetic field line. This implies that the path length of first-arriving MeV to deka-MeV protons is affected by interplanetary scattering. TSA of near-relativistic electrons results in a release time that shows significant scatter with respect to the EM emissions but with a trend of being delayed more with increasing distance between the flare and the nominal footpoint of the Earth-connected field line.

We explore the link between solar energetic particles (SEPs) observed at 1 AU and large-scale disturbances propagating in the solar corona, named after the Extreme ultraviolet Imaging Telescope (EIT) as EIT waves, which trace the lateral expansion of a coronal mass ejection (CME). A comprehensive search for SOHO/EIT waves was carried out for 179 SEP events during Solar Cycle 23 (1997 -2006). 87 % of the SEP events were found to be accompanied by EIT waves. In order to test if the EIT waves play a role in the SEP acceleration, we compared their extrapolated arrival time at the footpoint of the Parker spiral with the particle onset in the 26 eastern SEP events that had no direct magnetic connection to the Earth. We find that the onset of proton events was generally consistent with this scenario. However, in a number of cases the first near-relativistic electrons were detected too early. Furthermore, the electrons had in general only weakly anisotropic pitch-angle distributions. This poses a problem for the idea that the SEPs were accelerated by the EIT wave or in any other spatially confined region in the low corona. The presence of weak electron anisotropies in SEP events from the eastern hemisphere suggests that transport processes in interplanetary space, including cross-field diffusion, play a role in giving the SEPs access to a broad range of helio-longitudes.

We study the influence of the large-scale interplanetary magnetic field configuration on the solar energetic particles (SEPs) as detected at different satellites near Earth and on the correlation of their peak intensities with the parent solar activity. We selected SEP events associated with X and M-class flares at western longitudes, in order to ensure good magnetic connection to Earth. These events were classified into two categories according to the global interplanetary magnetic field (IMF) configuration present during the SEP propagation to 1 AU: standard solar wind or interplanetary coronal mass ejections (ICMEs). Our analysis shows that around 20% of all particle events are detected when the spacecraft is immersed in an ICME. The correlation of the peak particle intensity with the projected speed of the SEP-associated coronal mass ejection is similar in the two IMF categories of proton and electron events, ≈ 0.6. The SEP events within ICMEs show stronger correlation between the peak proton intensity and the soft X-ray flux of the associated solar flare, with correlation coefficient r = 0.67±0.13, compared to the SEP events propagating in the standard solar wind, r = 0.36±0.13. The difference is more pronounced for near-relativistic electrons. The main reason for the different correlation behavior seems to be the larger spread of the flare longitude in the SEP sample detected in the solar wind as compared to SEP events within ICMEs. We discuss to which extent observational bias, different physical processes (particle injection, transport, etc.), and the IMF configuration can influence the relationship between SEPs and coronal activity.The main and inevitable limitation of such statistical studies is that SEP intensities are generally measured at only one point. Its magnetic connection to the accelerator in the corona is not well known. It is often approximated by a Parker spiral. But this may not be true, as has been shown by event studies where SEPs reach the detector in transient interplanetary magnetic field (IMF) structures, i.e. interplanetary coronal mass ejections or ICMEs (Tranquille et al., 1987; Torsti, Riihonen, and Kocharov, 2 Malandraki et al., 2005;Kahler, Krucker, and Szabo, 2011). Masson et al. (2012b) showed recently that the majority of relativistic SEP events of solar cycle 23 were detected within or in the vicinity of ICMEs. These ICMEs stem from solar activity that occurred one or several days before the SEP event, so that the magnetic configuration had the time to expand and reach the Earth.This paper presents a re-assessment of statistical relationships between the peak intensities (and fluences) of particle events (i.e., near-relativistic electrons of tens to hundreds of keV and deka-MeV protons), and the parameters of the associated coronal activity (i.e., the peak SXR flux of the flare and the speed and width of the CME). Two categories of IMF configuration guiding the particles through the IP space are distinguished: standard solar wind and ICMEs. All SEP events of solar cycle 23...

-We present a statistical study on the observed solar radio burst emission associated with the origin of in situ detected solar energetic particles. Several proton event catalogs in the period 1996-2016 are used. At the time of appearance of the particle origin (flare and coronal mass ejection) we identified radio burst signatures of types II, III and IV by inspecting dynamic radio spectral plots. The information from observatory reports is also accounted for during the analysis. The occurrence of solar radio burst signatures is evaluated within selected wavelength ranges during the solar cycle 23 and the ongoing 24. Finally, we present the burst occurrence trends with respect to the intensity of the proton events and the location of their solar origin.

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Context. In the solar corona, shock waves are generated by flares and/or coronal mass ejections. They are able to accelerate electrons up to high energies and can thus be observed as type II bursts in the nonthermal solar radio radiation. In-situ measurements of shock waves in interplanetary space have shown that shock waves attached by whistler waves are preferably accompanied by the production of energetic electrons. Aims. Motivated by these observations, we study the interaction of electrons with such whistlers, which are excited by the protons accelerated by the shock. Methods. We start with a resonant whistler wave-proton interaction that accounts for the initial whistler wave generation. Then, we consider resonant whistler wave-electron interaction, treated with a relativistic approach that is responsible for the electron energization in the whistler wave field. Results. As a result, we show that electrons can be accelerated by a resonant wave particle (i.e., whistler-electron) interaction. This mechanism acts in the case of quasi-perpendicular shock waves. After acceleration, the energetic electrons are reflected by the associated shock wave back into the upstream region. The theoretical results are compared with observations, e.g., solar type II radio bursts.

We present the finalized catalog of solar energetic proton events detected by Wind/EPACT instrument over the period 1996−2016. Onset times, peak times, peak proton intensity and onset-to-peak proton fluence are evaluated for the two available energy channels, at about 25 and 50 MeV. We describe the procedure utilized to identify the proton events and to relate them to their solar origin (in terms of flares and coronal mass ejections). The statistical relationships between the energetic protons and their origin (linear and partial correlation analysis) are reported and discussed in view of earlier findings. Finally, the different trends found in the first eight years of solar cycles 23 and 24 are discussed. Miteva et al. 1 https://ngdc.noaa.gov/stp/satellite/goes/datanotes.html 2 http://umbra.nascom.nasa.gov/SEP/ 3 1 pfu = 1 proton/(cm 2 s sr) 4 http://server.sepserver.eu/, status: July 2017 5 The SEPEM 7.23−10.45 reference proton event list: http://dev.sepem.oma.be/help/event ref. html SOLA: Mitevaetal.tex; 3 January 2018; 1:39; p. 2 Wind/EPACT proton catalog the database with a focus on either energy-dependent statistics (Dierckxsens et al., 2015), or, among others, the distribution with respect to NOAA Solar Radiation Storm scale (Papaioannou et al., 2016). Recently, a new list of high energy protons (1995−2015), >500 MeV from the Electron Proton Helium Instrument [EPHIN] instrument aboard SOHO (Müller-Mellin et al., 1995) was presented by Kühl et al. (2017).Among the proton catalogs covering only SC23 is the 25 MeV proton database from the IMP-8 instrument (Cane, Richardson, and von Rosenvinge, 2010), as well as other listings 6 as noted by Papaioannou et al. (2016). Other particle lists using GOES and SOHO/COSTEP (Müller-Mellin et al., 1995) data were created for the purpose of testing forecasting procedures (Laurenza et al., 2009;Posner, 2007).Numerous statistical studies between SEP events and their solar origin (flares and CMEs) are known. Different works use differential or integral proton fluxes, flare class or/and fluence, CME projected speed or/and angular width, investigate the longitudinal effects, probability of occurrence or propose new statistical methods. The strength of the correlation between the protons and their solar origin is used to argue in favor of or against the particle driver. Below we outline studies covering at least one solar cycle. Presenting a complete account on all previous works is not the objective of this study.A comprehensive study is the energy dependent statistics provided by Dierckxsens et al. (2015) based on re-calibrated data from GOES and IMP-8 instruments over 10 energy channels (from 5 to 200 MeV) and in the entire SC23 (using SEPEM data 7 , Crosby et al., 2015). The work provides results based on differential and integral proton intensities. The main result is the larger correlation between flares and high energy protons, whereas the low energy protons correlate better with CME speed. Among the other works over SC23 that provide also new particle lists are: Cane, R...