Energetic Particle Observations during the 2000 July 14 Solar Event

Bieber, J. W.; Dröge, W.; Evenson, P. A.; Pyle, R.; Ruffolo, D.; Pinsook, Udomsilp; Tooprakai, P.; Rujiwarodom, M.; Khumlumlert, T.; Krucker, S.

doi:10.1086/338246

Cited by 159 publications

(182 citation statements)

References 25 publications

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“…As a plausible alternative, we propose that the relatively slow shock of eruption A was SEP-productive only near the Sun, while a temporal trapping of SEPs in a possible solar wind structure with a bottleneck behind the Earth's orbit (e.g., Bieber et al 2002) resulted in extended intensity-time profiles with low values of the SEP flux anisotropy. At distances >0.2 AU from the Sun, as suggested by the vanishing anisotropy, shock A became unable to accelerate high-energy protons, possibly by becoming quasiparallel and surrounded by not very turbulent plasma, or even by decaying completely on the Earth-connected magnetic field lines.…”

Section: Discussionmentioning

confidence: 99%

Observation of a solar energetic particle event behind previous coronal mass ejection

Al-Sawad

Saloniemi

Laitinen

et al. 2009

A&A

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On 2001 October 19-21 the Energetic and Relativistic Nuclei and Electron (ERNE) instrument on the Solar and HeliosphericObservatory (SOHO) observed two gradual solar energetic particle (SEP) events separated by 15 h, in association with two X1.6/2B solar flares and halo coronal mass ejections (CMEs). The observational data suggest that the second acceleration of ∼10−100 MeV protons occurred behind the first CME and the previous CME was not an obstacle for new particles to directly reach 1 AU. The proton flux anisotropy data support the idea that the particle production significantly declined in about 10 h after the shock wave started, while the prolonged temporal profile of the solar energetic particle event was due to a slow transport of previously accelerated particles in the interplanetary space. These observations call into question the view that in all gradual events high-energy particles are continuously produced at a CME bow shock as it travels from near the Sun to beyond 1 AU.

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Section: Discussionmentioning

confidence: 99%

Observation of a solar energetic particle event behind previous coronal mass ejection

Al-Sawad

Saloniemi

Laitinen

et al. 2009

A&A

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“…Previous observational studies (e.g. Anderson et al 1995;Roelof et al 1992;Bieber et al 2002;Tan et al 2009) have provided evidence of the presence of discrete solar windinterplanetary magnetic field structures beyond 1 AU, which are able to reflect SEPs back to the inner heliosphere. The present study provides another example in which the electron propagation is influenced by a similar structure.…”

Section: Discussionmentioning

confidence: 99%

Solar near-relativistic electron observations as a proof of a back-scatter region beyond 1 AU during the 2000 February 18 event

Agueda

Vainio

Lario

2010

A&A

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Aims. We study the near-relativistic (NR; >30 keV) electron event observed on 2000 February 18 by near-Earth spacecraft. Previous works have explained this event by assuming that the propagation of NR electrons is essentially "scatter-free" at heliocentric radial distances r < 1 AU, and that beyond 1 AU particles are "back-scattered" by magnetic field irregularities. Methods. Our aim is to re-visit this interplanetary propagation scenario and infer the injection profile at the Sun by fitting the electron directional intensities observed by the Advanced Composition Explorer. Results. We use a Monte Carlo transport model to explore this approach. We assume that the interplanetary magnetic field is an Archimedean spiral and that the interplanetary transport of NR electrons is characterized by a large radial mean free path (λ r > 0.5 AU) and anisotropic pitch-angle scattering for r < 1 AU, and a small radial mean free path (λ r < 0.5 AU) and isotropic scattering in the back-scatter region. Conclusions. The event cannot be explained without assuming a back-scatter region beyond 1 AU. The best fit is obtained by assuming λ r = 3.2 AU in the inner heliosphere and a back-scatter region characterized by a small mean free path λ r = 0.2 AU located beyond 1.2 AU.

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“…Whether a given SEP event is a GLE depends on the detection of the secondary particles usually by neutron monitors (NMs) at cosmic ray stations. For a given GLE, different NMs show different time profiles (e.g., Bieber et al 2002;McCracken et al 2008;Moraal and McCracken 2011), because of different asymptotic look angles and rigidities of the NMs combined with anisotropy of the particles.…”

Section: Problems In Defining and Characterizing Glesmentioning

confidence: 99%

What Are Special About Ground-Level Events?

et al. 2012

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Ground level events (GLEs) occupy the high-energy end of gradual solar energetic particle (SEP) events. They are associated with coronal mass ejections (CMEs) and solar flares, but we still do not clearly understand the special conditions that produce these rare events. During Solar Cycle 23, a total of 16 GLEs were registered, using ground-based neutron monitor data. We first ask if these GLEs are clearly distinguishable from other SEP events observed from space. Setting aside possible difficulties in identifying all GLEs consistently, we then try to find observables which may unmistakably isolate these GLEs by studying the basic properties of the associated eruptions and the active regions (ARs) that produced them. It is found that neither the magnitudes of the CMEs and flares nor the complexities of the ARs give sufficient conditions for GLEs. It is possible to find CMEs, flares or ARs that are not associated with GLEs but that have more extreme properties than those associated with GLEs. We also try to evaluate the importance of magnetic field connection of the AR with Earth on the detection of GLEs and their onset times. Using the potential field source surface (PFSS) model, a half of the GLEs are found to be well-connected. However, the GLE onset time with respect to the onset of the associated flare and CME does not strongly depend on how well-connected the AR is. The GLE onset behavior may be largely determined by when and where the CME-driven shock develops. We could not relate the shocks responsible for the onsets of past GLEs with features in solar images, but the combined data from the Solar TErrestrial RElations Observatory (STEREO) and the Solar Dynamics Observatory (SDO) have the potential to change this for GLEs that may occur in the rising phase of Solar Cycle 24.

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Energetic Particle Observations during the 2000 July 14 Solar Event

Cited by 159 publications

References 25 publications

Observation of a solar energetic particle event behind previous coronal mass ejection

Observation of a solar energetic particle event behind previous coronal mass ejection

Solar near-relativistic electron observations as a proof of a back-scatter region beyond 1 AU during the 2000 February 18 event

What Are Special About Ground-Level Events?

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