Solar Cosmic Rays of February, 1956 and Their Propagation through Interplanetary Space

Meyer, P.; Parker, E. N.; Simpson, J. A.

doi:10.1103/physrev.104.768

Cited by 364 publications

(141 citation statements)

References 20 publications

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“…We interpret these results as evidence that (a) equilibrium has been reached, with the steady-state anisotropy of < 10% which i s probably due to co-rotation effects, and (b) that the characteristic time constant, decrease of observed flux is determined mainly by the interplanetary magnetic field irregularities beyond the orbit of the spacecraft. Since the decrease of intensity i s exponential, the depth of the diffusion region must be finite (Meyer, Parker and Simpson, 1956) for protons in the 0.6-70 MeV energy range, i.e. the number nf protons escaping i s proportional to the number present i n the region of space accessible to observation.…”

Section: Propagation Of Protons From Identified Solar Flaresmentioning

confidence: 99%

Protons associated with centers of solar activity and their propagation in interplanetary magnetic field regions corotating with the Sun

Fan¹,

Pick²,

Pyle³

et al. 1968

J. Geophys. Res.

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134

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The Pioneer-6 and Pioneer-7 space probes carried charged-particle telescopes which measure, for the first time, both the direction of arrival and differential energy spectra of protons and alpha particles. The intensity changes, directional distributions and energy spectra of proton fluxes associated with solar activity are investigated. The ' NASA predoctoral trainee. intensity increases extending i n energy to more than 50 MeV are observed, superposed on the enhanced flux. These increases displayed short transit times and short rise times. Both the enhanced and flare-produced fluxes propagate along the spiral interplanetary magnetic field from the western hemisphere of the Sun. From these observations we are led to a model i n which the magnetic fields from the active center are spread out over a longitude range of 100-180 degrees i n the solar corona. The existence of strong unidirectional anisotropies i n the initial phases of flare proton events implies that l i t t l e scattering occurs between the Sun and spacecraft. However, the gradual approach to an isotropic flux a t late times indicates that the decay phase i s controlled by the interplanetary magnetic field.

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Section: Propagation Of Protons From Identified Solar Flaresmentioning

confidence: 99%

Protons associated with centers of solar activity and their propagation in interplanetary magnetic field regions corotating with the Sun

Fan¹,

Pick²,

Pyle³

et al. 1968

J. Geophys. Res.

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134

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“…Early observations suggested that the resulting particle transport is diffusive (Meyer et al 1956;Roelof 1969). Hence a simple description of the SEP transport can be provided by time-dependent solutions of a spatial diffusion equation with a diffusion coefficient determined by the spectrum of the turbulence (e.g., Kóta et al 1982;Artmann et al 2011, and references therein).…”

Section: An Application To the Transport Of Solar Energetic Particlesmentioning

confidence: 99%

The telegraph equation for cosmic-ray transport with weak adiabatic focusing

Litvinenko

Schlickeiser

2013

A&A

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Time-dependent solutions of a spatial diffusion equation are often used to describe the transport of solar energetic particles, accelerated in large solar flares. Approximate analytical solutions of the diffusion approximation can complement and guide detailed numerical solutions of the Fokker-Planck equation for the particle distribution function. The accuracy of the diffusion approximation is limited, however, because the signal propagation speed is infinite in the diffusion limit. An improved description of cosmic-ray transport is provided by the telegraph equation, characterised by a finite signal propagation speed. We derive the telegraph equation for the particle density, taking into account adiabatic focusing in a large-scale interplanetary magnetic field in a weak focusing limit. As an illustration, we calculate a propagating pulse solution of the telegraph equation, determine the rise time when the maximum particle intensity is reached at a given distance from the Sun, and compare the results with those obtained in the diffusion approximation. In comparison with the diffusion equation, the telegraph equation predicts an asymmetrical shape of the pulse and a shorter rise time. These potentially significant differences suggest that the more accurate telegraph equation should be used in analysis of the solar energetic particle data, at least to quantify the accuracy of the focused diffusion model.

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“…In the present study we consider the outstanding ground level enhancement GLE05 on 23 February 1956, the largest one in the entire history of observations of solar cosmic rays. This maximal GLE has been extensively studied for a period more than 60 years ( [3,4] and reference therein). The GLE05 was caused by a large solar flare with importance of 3+ (or 3B) that occurred at 03:31 UT in the active region with heliographic coordinates 25°N, 85°W.…”

Section: Introductionmentioning

confidence: 99%

Cosmic ray ionization effect in the atmosphere during the maximal GLE05 − on 23.02.1956

Velinov¹,

Balabin²,

Маурчев³

2017

Proceedings of 35th International Cosmic Ray Conference — PoS(ICRC2017)

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The ground level enhancements (GLEs) due to solar cosmic rays (SCRs) are of significant astrophysical, cosmophysical and geophysical interest for a number of planetary processes on the Earth. In the present work the ionization rate profiles in the Earth's atmosphere during the outstanding ground level enhancement GLE05 on 23 February 1956, the largest one in the entire history of observations of SCRs, are obtained. The contribution of the galactic cosmic rays (GCRs) is also taken into account. The ionization in the atmosphere is calculated using the energetic spectra of solar protons, GCRs and the corresponding atmospheric cascade simulation. The spectra of solar cosmic rays are derived on the basis of ground-based measurements with neutron monitors. This method is based on solving the inverse problem -reconstruction of SCR spectrum on the boundary of the magnetosphere. The contemporary magnetosphere model "Tsyganenko 01 and 03" is used in this method. The calculation of asymptotic cones (AK) held with increments of 0.001 GV in the range of 1-20 GV. The aforementioned method is developed in the Polar Geophysical Institute (in Apatity) of the Russian Academy of Sciences. Recent simulations with RUSCOSMICS software package (based on GEANT4 program of CERN) are carried out. The energy deposit of solar protons and GCRs in the atmosphere is received. The ion production rate profiles in the stratosphere and troposphere (the region 0-40 km) are calculated for geomagnetic cut-off rigidities 1, 2, 3 and 5 GV (i.e. polar, subpolar, higher and middle latitudes, respectively). The so obtained ionization profiles are compared and thoroughly discussed. Implementations of these results are also debated. The obtained results are important for the improvement of the recent models of cosmic ray induced ionization in the whole atmosphere, for the determination of electron and ion density in the middle and lower atmosphere (troposphere), for the various atmospheric processes (as for instance in atmospheric chemistry and physicsozone production, global electric circuit between the ground and ionosphere), for the studies of solar-terrestrial influences on space weather and space climate) and for many other applications.

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Solar Cosmic Rays of February, 1956 and Their Propagation through Interplanetary Space

Cited by 364 publications

References 20 publications

Protons associated with centers of solar activity and their propagation in interplanetary magnetic field regions corotating with the Sun

Protons associated with centers of solar activity and their propagation in interplanetary magnetic field regions corotating with the Sun

The telegraph equation for cosmic-ray transport with weak adiabatic focusing

Cosmic ray ionization effect in the atmosphere during the maximal GLE05 − on 23.02.1956

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