Fluxes and fluences of SEP events derived from SOLPENCO

Abstract. We have developed aran04 a tool for rapid predictions of proton flux and fluence profiles observed during gradual solar energetic particle (SEP) events and upstream of the associated traveling interplanetary shocks. This code, named SOLPENCO (for SOLar Particle ENgineering COde), contains a data base with a large set of interplanetary scenarios under which SEP events develop. These scenarios are basically defined by the solar longitude of the parent solar activity, ranging from E75 to W90, and by the position of the observer, located at 0.4 AU or at 1.0 AU, from the Sun. We are now analyzing the performance and reliability of SOLPENCO. We address here two features of SEP events especially relevant to space weather purposes: the peak flux and the fluence. We analyze how the peak flux and the fluence of the synthetic profiles generated by SOLPENCO vary as a function of the strength of the CME-driven shock, the heliolongitude of the solar parent activity and the particle energy considered. In particular, we comment on the dependence of the fluence on the radial distance of the observer (which does not follow an inverse square law), and we draw conclusions about the influence of the shock as a particle accelerator in terms of its evolving strength and the heliolongitude of the solar site where the SEP event originated.

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Variable Ion Compositions of Solar Energetic Particle Events in the Inner Heliosphere: A Field Line Braiding Model with Compound Injections

The Astrophysical Journal ◽

10.3847/1538-4357/ac3233 ◽

2022 ◽

Vol 924 (1) ◽

pp. 22

Author(s):

Fan Guo ◽

Lulu Zhao ◽

Christina M. S. Cohen ◽

Joe Giacalone ◽

R. A. Leske ◽

...

Keyword(s):

Magnetic Field ◽

Energetic Particle ◽

Radial Distance ◽

Solar Energetic Particle ◽

The Sun ◽

Ion Composition ◽

Source Regions ◽

Solar Energetic Particle Events ◽

Composition Ratios ◽

Inner Heliosphere

Abstract We propose a model for interpreting highly variable ion composition ratios in solar energetic particle (SEP) events recently observed by the Parker Solar Probe (PSP) at 0.3–0.45 au. We use numerical simulations to calculate SEP propagation in a turbulent interplanetary magnetic field with a Kolmogorov power spectrum from large scales down to the gyration scale of energetic particles. We show that when the source regions of different species are offset by a distance comparable to the size of the source regions, the observed energetic particle composition He/H can be strongly variable over more than two orders of magnitude, even if the source ratio is at the nominal value. Assuming a 3He/4He source ratio of 10% in impulsive 3He-rich events and the same spatial offset of the source regions, the 3He/4He ratio at observation sites also vary considerably. The variability of the ion composition ratios depends on the radial distance, which can be tested by observations made at different radial locations. We discuss the implications of these results on the variability of ion composition of impulsive events and on further PSP and Solar Orbiter observations close to the Sun.

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Looking for the FIP Effect in EUV Spectra: Examining the Solar Case

International Astronomical Union Colloquium ◽

10.1017/s0252921100036472 ◽

1996 ◽

Vol 152 ◽

pp. 511-518

Author(s):

Bernhard Haisch ◽

Julia L. R. Saba ◽

Jean-Paul Meyer

Keyword(s):

Solar Wind ◽

Energetic Particle ◽

Solar Energetic Particle ◽

The Sun ◽

X Ray ◽

Elemental Abundances ◽

Different Types ◽

Abundance Anomalies ◽

Over Time ◽

Coronal Structures

Systematic differences between elemental abundances in the corona and in the photosphere have been found in the Sun. The abundance anomalies are correlated with the first ionization potentials (FIP) of the elements. The overall pattern is that low-FIP elements are preferentially enhanced relative to high-FIP elements by about a factor of four; the transition occurs at about 10 eV. This phenomenon has been measured in the solar wind and solar energetic particle composition, and in EUV and X-ray spectra of the corona and flares. The FIP effect should eventually offer valuable clues into the process of heating, ionization and injection of material into coronal and flaring loops for the Sun and other stars. The situation for the Sun is remarkably complex: substantial abundance differences occur between different types of coronal structures, and variations occur over time in the same region and from flare to flare. Anomalies such as enhanced Ne/O ratios, distinctly at odds with the basic FIP pattern, have been reported for some flares. Are the high-FIP elements underabundant or the low-FIP elements overabundant with respect to hydrogen? This issue, which has a significant impact in physical interpretation of coronal spectra, is still a subject of controversy and an area of vigorous research.

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INTERPRETING THE PROPERTIES OF SOLAR ENERGETIC PARTICLE EVENTS BY USING COMBINED IMAGING AND MODELING OF INTERPLANETARY SHOCKS

The Astrophysical Journal ◽

10.1088/0004-637x/735/1/7 ◽

2011 ◽

Vol 735 (1) ◽

pp. 7 ◽

Cited By ~ 76

Author(s):

A. P. Rouillard ◽

D. Odstrc˘il ◽

N. R. Sheeley ◽

A. Tylka ◽

A. Vourlidas ◽

...

Keyword(s):

Energetic Particle ◽

Solar Energetic Particle ◽

Interplanetary Shocks ◽

Solar Energetic Particle Events ◽

Combined Imaging

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A Turbulent History

Solar Energetic Particles - Lecture Notes in Physics ◽

10.1007/978-3-030-66402-2_2 ◽

2021 ◽

pp. 19-48

Author(s):

Donald V. Reames

Keyword(s):

Shock Waves ◽

Coronal Mass Ejections ◽

Energetic Particle ◽

Electron Beams ◽

Diffusion Theory ◽

Plasma Temperature ◽

Solar Energetic Particle ◽

The Sun ◽

Suprathermal Ions ◽

And Diffusion

AbstractLarge solar energetic-particle (SEP) events are clearly associated in time with eruptive phenomena on the Sun, but how? When large SEP events were first observed, flares were the only visible candidate, and diffusion theory was stretched to explain how the particles could spread through space, as widely as observed. The observation of coronal mass ejections (CMEs), and the wide, fast shock waves they can drive, provided better candidates later. Then small events were found with 1000-fold enhancements in 3He/4He that required a different kind of source—should we reconsider flares, or their open-field cousins, solar jets? The 3He-rich events were soon associated with the electron beams that produce type III radio bursts. It seems the radio astronomers knew of both SEP sources all along. Sometimes the distinction between the sources is blurred when shocks reaccelerate residual 3He-rich impulsive suprathermal ions. Eventually, however, we would even begin to measure the source-plasma temperature that helps to better distinguish the SEP sources.

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Determination of Solar Energetic Particle anisotropies based on four-sector measurements - Study based on STEREO/SEPT in preperation of SolO/EPT

10.5194/egusphere-egu2020-17554 ◽

2020 ◽

Author(s):

Maximilian Bruedern ◽

Nina Dresing ◽

Bernd Heber ◽

Lars Berger ◽

Alexander Kollhoff ◽

...

Keyword(s):

Magnetic Field ◽

Pitch Angle ◽

Radial Distance ◽

Solar Energetic Particle ◽

The Sun ◽

Angle Scattering ◽

Bootstrap Approach ◽

The Magnetic Field ◽

The Imf

With the launch of Solar Orbiter (SolO) Solar Energetic Particles (SEPs) can be observed at a radial distance of 0.284 to 0.9 AU and an inclination out of the ecliptic up to 34 degree. The properties of SEP observations carry information about their source at the Sun as well as their transport through the interplanetary medium. Their energy is mostly determined close to the Sun. As SEPs propagate outward along the Interplanetary Magnetic Field (IMF) the pitch-angle with respect to the local field is systematically focused due to the radially decreasing IMF. However, stochastic changes are induced by scattering at fluctuations of the IMF. Often the first order anisotropy of SEPs is calculated to disentangle imprints of source and transport. Strong anisotropies indicate periods of weak pitch-angle scattering. Although many modeling and observational studies are based on the anisotropy, its uncertainty is often neglected which could result in inaccurate conclusions. Therefore, we propose a new method based on a bootstrap approach where we consider (1) directional instrument responses, (2) the variation of the magnetic field, and (3) the stochastic nature of detection. Here, we present our procedure and final results for different SEP events using measured data of the IMF and particle fluxes by the Solar Electron and Proton Telescope (SEPT) on board of each STEREO spacecraft. The SEPT provides four viewing directions with a view cone of 0.66 sr each on a three axis stabilized spacecraft. In contrast the Electron and Proton Telescope (EPT) on board SolO also consists of four viewing directions but each telescope has a much smaller view cone of 0.21 sr. Due to the very similar instrument setup we can apply our method both to the SEPT and EPT.

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Interplanetary shocks as a source of sustained gamma-ray emission from the Sun

10.5194/egusphere-egu2020-21334 ◽

2020 ◽

Author(s):

Nat Gopalswamy ◽

Pertti Mäkelä

Keyword(s):

Gamma Rays ◽

Gamma Ray ◽

Solar Energetic Particle ◽

Impulsive Phase ◽

High Energy ◽

The Sun ◽

Interplanetary Shocks ◽

Neutral Pions ◽

Flare Loops ◽

Gamma Ray Emission

It has recently been shown that the sustained gamma-ray emission (SGRE) from the Sun that lasts for hours beyond the impulsive phase of the associated flare is closely related to radio emission from interplanetary shocks (Gopalswamy et al. 2019, JPhCS, 1332, 012004, 2019). This relationship supports the idea that >300 MeV protons accelerated by CME-driven shocks propagate toward the Sun, collide with chromospheric protons and produce neutral pions that promptly decay into >80 MeV gamma-rays. There have been two challenges to this idea. (i) Since the location of the shock can be halfway between the Sun and Earth at the SGRE end time, it has been suggested that magnetic mirroring will not allow the high energy protons to precipitate. (ii) Lack of correlation between the number protons involved in the production of >100 MeV gamma-rays (Ng) and the number of protons (Nsep) in the associated solar energetic particle (SEP) event has been reported. In this paper, we show that the mirror ratio problem is no different from that in flare loops where electrons and protons precipitate to produce impulsive phase emissions. We also suggest that the lack of Ng &#8211; Nsep correlation is due to two reasons: (1) Nsep is underestimated in the case of eruptions happening at large ecliptic latitudes because the high-energy protons accelerated near the nose do not reach the observer. (2) In the case of limb events, the Ng is underestimated because gamma-rays from some part of the extended gamma-ray source do not reach the observer.

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Strength of Coronal Mass Ejection‐driven Shocks near the Sun and Their Importance in Predicting Solar Energetic Particle Events

The Astrophysical Journal ◽

10.1086/521716 ◽

2007 ◽

Vol 670 (1) ◽

pp. 849-856 ◽

Cited By ~ 23

Author(s):

Chenglong Shen ◽

Yuming Wang ◽

Pinzhong Ye ◽

X. P. Zhao ◽

Bin Gui ◽

...

Keyword(s):

Coronal Mass Ejection ◽

Energetic Particle ◽

Solar Energetic Particle ◽

The Sun ◽

Solar Energetic Particle Events ◽

Mass Ejection

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Characterizing the Dynamics of CME-Driven Coronal Bright Fronts Using The SPREAdFAST Framework

10.5194/egusphere-egu21-9809 ◽

2021 ◽

Author(s):

Mohamed Nedal ◽

Kamen Kozarev ◽

Rositsa Miteva

Keyword(s):

Energetic Particle ◽

Large Scale ◽

Numerical Models ◽

Solar Energetic Particle ◽

Time Dependent ◽

Radiation Environment ◽

Source Surface ◽

The Sun ◽

Particle Radiation ◽

Field Source

In this work, we present a full characterization of over 50 historical Coronal Mass Ejection (CME)-driven compressive waves in the low solar corona, related to solar energetic particle events near Earth, using the Solar Particle Radiation Environment Analysis and Forecasting - Acceleration and Scattering Transport (SPREAdFAST) framework. SPREAdFAST is a physics-based, operational heliospheric solar energetic particle (SEP) forecasting system, which incorporates a chain of data-driven analytic and numerical models for estimating: a) coronal magnetic field from Potential Field Source Surface (PFSS) and Magnetohydrodynamics (MHD); b) dynamics of large-scale coronal (CME-driven) shock waves; c) energetic particle acceleration; d) scatter-based, time-dependent SEP propagation in the heliosphere to specific time-dependent positions. SPREAdFAST allows for producing predictions of SEP fluxes at multiple locations in the inner heliosphere, by modeling their acceleration at CMEs near the Sun, and their subsequent interplanetary transport. We used sequences of base-difference images obtained from the AIA instrument on board the SDO satellite, with 24-second cadence. We calculated time-dependent speeds in both the radial and lateral (parallel to the solar limb) directions, mean intensities and thicknesses of the fronts, and major and minor axes. This is essential for characterizing the SEP spectra near the Sun. The kinematics measurements were used to generate time-dependent 3D geometric models of the wave fronts and time-dependent plasma diagnostics using MHD and DEM model results.&#160;&#160;

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