Spaceship Earth Observations of the Easter 2001 Solar Particle Event

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

doi:10.1086/381801

Cited by 119 publications

(108 citation statements)

References 14 publications

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“…Bieber et al (2004) conclude that the onset of particle injection onto the Sun-Earth field line was at 13:42 UT ± 1 min, and Agueda et al (2009) conclude that the electron injection started at 13:48 UT at 80 keV. These two previous results are in accordance with our injection time at 13:45 UT.…”

Section: Comparison With Measured Datasupporting

confidence: 89%

A diffusive description of the focused transport of solar energetic particles

Artmann

Schlickeiser

Agueda

et al. 2011

A&A

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The transport of solar energetic charged particles along the interplanetary magnetic field in the ecliptic plane of the sun can be described roughly by a one-dimensional diffusion equation. Large-scale spatial variations of the guide magnetic field can be taken into account by adding an additional term to the diffusion equation that includes the effect of adiabatic focusing. We solve this equation analytically by assuming a point-like particle injection in time and space and a spatial power-law dependence for the focusing length and the spatial diffusion coefficient. We infer the intensity-and anisotropy-time profiles of solar energetic particles from this solution. Through these the influence of different assumptions for the diffusion parameters can be seen in a mathematically closed form. The comparison of calculated and measured intensity-and anisotropy-time profiles, which are a powerful diagnostic tool for interplanetary particle transport, gives information about the large-scale spatial dependence of the focusing length and the diffusion coefficient. For an exceptionally large solar energetic particle event, which did occur on 2001 April 15, we fit the 27−512 keV electron intensities and anisotropies observed by the Wind spacecraft using the theoretically derived profiles. We find a linear spatial dependence of the mean free path along the guiding magnetic field. We also find the mean free path to be energy independent, which supports the theory of "velocity-dependent diffusion". This means that the intensity profiles for the discussed energies exhibit the same shape if they are plotted against the traveled distance and not against the time. In this case the profiles differ only in their maximum values and we can determine the energy spectra of the solar flare electrons out of the scaling factor we need to fit the data. The derived spectra exhibits a power-law dependence ∝E −3 kin in an energy range from ∼50 keV to ∼500 keV.

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Section: Comparison With Measured Datasupporting

confidence: 89%

A diffusive description of the focused transport of solar energetic particles

Artmann

Schlickeiser

Agueda

et al. 2011

A&A

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“…They are known to accelerate solar energetic particles (SEPs) to high energies (e.g., Reames 1999;Kahler 2001), even GeV energies (Bieber et al 2004) during the so-called gradual SEP events. Fermi acceleration is the likely acceleration mechanism for quasi-parallel shocks while gradient-drift acceleration operates at quasi-perpendicular shocks (e.g., Lee 2000).…”

Section: Science Question 6: 'What Are the Roles Of Shocks Reconnectmentioning

confidence: 99%

The Wide-Field Imager for Solar Probe Plus (WISPR)

et al. 2015

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mission designed to orbit as close as 7 million km (9.86 solar radii) from Sun center. WISPR employs a 95 • radial by 58 • transverse field of view to image the fine-scale structure of the solar corona, derive the 3D structure of the large-scale corona, and determine whether a dust-free zone exists near the Sun. WISPR is the smallest heliospheric imager to date yet it comprises two nested wide-field telescopes with large-format (2 K × 2 K) APS CMOS detectors to optimize the performance for their respective fields of view and to minimize the risk of dust damage, which may be considerable close to the Sun. The WISPR electronics are very flexible allowing the collection of individual images at cadences up to 1 second at perihelion or the summing of multiple images to increase the signal-to-noise when the spacecraft is further from the Sun. The dependency of the Thomson scattering emission of the corona on the imaging geometry dictates that WISPR will be very sensitive to the emission from plasma close to the spacecraft in contrast to the situation for imaging from Earth orbit. WISPR will be the first 'local' imager providing a crucial link between the large-scale corona and the in-situ measurements.

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“…A sample SEP event is shown in Figure 1 [Bieber et al, 2004]. The start time of the intensity increase in neutron monitors (bottom plot) is earlier than that of the low-energy proton flux (top plot).…”

Section: Introductionmentioning

confidence: 99%

Development of a ground level enhancement alarm system based upon neutron monitors

et al. 2006

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[1] We have developed a system that watches for count rate increases recorded in real time by eight neutron monitors, which triggers an alarm if a ground level enhancement (GLE) is detected. In this work, we determine optimal strategies for detecting the GLE event at a very early stage, while still keeping the false alarm rate at a very low level. We study past events to optimize appropriate intensity threshold values and a baseline to determine the intensity increase. The highest-level alarm, which we term an ''alert,'' is generated when a 4% increase is recorded at three stations in 3 min averaged data. At this level, the false alarm rate obtained by backtesting over the past 4.4 years is zero. Ten GLEs occurred in this period, and our system produced GLE alarms for nine events. Alarm times for these nine events are compared with satellite proton data.

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Spaceship Earth Observations of the Easter 2001 Solar Particle Event

Cited by 119 publications

References 14 publications

A diffusive description of the focused transport of solar energetic particles

A diffusive description of the focused transport of solar energetic particles

The Wide-Field Imager for Solar Probe Plus (WISPR)

Development of a ground level enhancement alarm system based upon neutron monitors

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