Time Structure of Solar Flare Proton Events

1968 ◽  
Vol 1 (4) ◽  
pp. 148-149
Author(s):  
B. J. Stone
Keyword(s):  
Solar Flare ◽  
Interplanetary Space ◽  
Cosmic Ray ◽  
Solar Proton ◽  
Progress Report ◽  
Flare Activity ◽  
Space Probe ◽  
Short Term ◽  
The Earth ◽  
The Times

This paper is a progress report on an examination of the short-term variability of solar proton flux in interplanetary space at times of solar flare activity. The data are from the GRCSW cosmic-ray detector on board the Pioneer 7 space probe, which, at the times to be discussed, was more than a million miles from the Earth.

Time variations of directional cosmic ray intensity at low latitudes - III. Interpretation of solar daily variation and changes of east-west asymmetry

1961 ◽  
Vol 263 (1312) ◽  
pp. 127-135 ◽  
Keyword(s):  
Energy Spectrum ◽  
Interplanetary Space ◽  
Daily Variation ◽  
Cosmic Ray ◽  
Local Source ◽  
Cosmic Ray Intensity ◽  
The Earth ◽  
Low Latitudes ◽  
Time Variations ◽  
East West

The daily variation of cosmic ray intensity at low latitudes can under certain conditions be associated with an anisotropy of primary radiation. During 1957-8, this anisotropy had an energy spectrum of variation of the form aϵ -0.8±0.3 and corresponded to a source situated at an angle of 112 ± 10° to the left of the earth-sun line. The daily variation which can be associated with a local source situated along the earth-sun line has an energy spectrum of variation of the form aϵ 0 . Increases in east-west asymmetry and the associated daily variation for east and west directions can be explained by the acceleration of cosmic ray particles crossing beams of solar plasma in the neighbourhood of the earth. For beams of width 5 x 10 12 cm with a frozen magnetic field of the order of 10 -4 G, a radial velocity of about 1.5 x 108 cm/s is required. The process is possible only if the ejection of beams takes place in rarefied regions of inter­ planetary space which extend radially over active solar regions. An explanation of Forbush, type decreases observed at great distances from the earth requires similar limitation on the plasma density and conductivity of regions of interplanetary space. The decrease of east-west asymmetry associated with world-wide decreases of intensity and with SC magnetic storms is consistent with a screening of the low-energy cosmic ray particles due to magnetic fields in plasma clouds.

TRANSIENT DECREASES IN COSMIC RAY INTENSITY DURING THE PERIOD OCTOBER 1956 TO JANUARY 1958

1959 ◽  
Vol 37 (5) ◽  
pp. 569-578 ◽  
Author(s):  
A. G. Fenton ◽  
D. C. Rose ◽  
K. G. McCracken ◽  
B. G. Wilson
Keyword(s):  
Forbush Decrease ◽  
Cosmic Ray ◽  
Statistical Accuracy ◽  
Short Term ◽  
Cosmic Ray Intensity ◽  
The Earth ◽  
Controlling Mechanism ◽  
Intensity Changes ◽  
Recurrence Tendency ◽  
Cosmic Ray Flux

Recent nucleon intensity data obtained from high counting rate recorders at Ottawa and Hobart, and subsidiary stations, have been examined for evidence for the superposition of transient decreases. It is concluded that, with the statistical accuracy now available due to the high counting rates, it is possible to distinguish two types of transient decreases in the observed variations, superimposed upon the slower 11-year intensity changes. One of these is an almost symmetrical event lasting up to 2 weeks and exhibiting a recurrence tendency of about 27 days, while the other is the more abrupt Forbush decrease which recovers over a period of several days. The evidence indicates that the intensity-controlling mechanism responsible for these short-term transient changes is able to influence the cosmic ray flux at the earth independently of other events that may be in progress at the time. There is also evidence that the physical process controlling the Forbush type of decrease operates over a volume large compared with the earth because the intensity changes at places as far apart as Ottawa, Canada, and Hobart, Tasmania, show changes that are the same within the accuracy of the measurements.

Energetic solar particle propagation and the structure of interplanetary space

1968 ◽  
Vol 46 (10) ◽  
pp. S812-S818 ◽  
Author(s):  
S. N. Vernov ◽  
E. V. Gortchakov ◽  
Yu. I. Logatchov ◽  
G. P. Lyubimov ◽  
N. V. Pereslegina ◽  
...  
Keyword(s):  
Solar Activity ◽  
Interplanetary Space ◽  
Cosmic Ray ◽  
Solar Proton ◽  
The Sun ◽  
Energetic Solar Particle ◽  
Radial Gradient ◽  
Solar Particle ◽  
Proton Fluxes ◽  
Particle Propagation

This work studies the structure of interplanetary space between the orbits of Venus and Mars on the basis of solar proton streaming and cosmic-ray variations measured from Soviet and U.S. spacecraft. Solar proton fluxes measured from spacecraft at various distances from the sun and in various solar activity phases are intercompared. The problem of the large radial gradient of protons with energies of 1–5 MeV is discussed.

Semidiurnal Anisotropy of Galactic Cosmic Ray Intensity

1971 ◽  
Vol 49 (1) ◽  
pp. 34-48 ◽  
Author(s):  
G. Subramanian
Keyword(s):  
Energy Spectrum ◽  
Counting Rate ◽  
Interplanetary Space ◽  
Cosmic Ray ◽  
Cosmic Ray Intensity ◽  
The Earth ◽  
Positive Exponent ◽  
Semidiurnal Variation ◽  
Using Data ◽  
Galactic Cosmic Ray

The semidiurnal variation of galactic cosmic ray intensity is investigated using data from mainly high counting rate neutron and meson monitors during 1964–1968. It is shown that in order to explain the observed semidiurnal variation it is necessary that an anisotropy of cosmic ray intensity be present in interplanetary space. The energy spectrum and the asymptotic latitude dependence of the anisotropy are then determined. The energy spectrum has a positive exponent close to + 1 for the power law in energy. The strength of the anisotropy decreases more rapidly than cosλ with increasing asymptotic latitude λ, both cos2λ and cos3λ being acceptable. The distribution of cosmic ray intensity in the range of heliolatitudes ± 7.25° at the orbit of the earth, obtained using data from the Ottawa neutron monitor, does not support the explanation of the semidiurnal variation based on the models of Subramanian and Sarabhai or Lietti and Quenby.

Long Duration Solar Flare Events and Cosmic Ray Modulation (1969-1992)

1994 ◽  
Vol 144 ◽  
pp. 499-502
Author(s):  
A. Antalová ◽  
K. Kudela ◽  
D. Venkatesan ◽  
J. Rybák
Keyword(s):  
Solar Cycle ◽  
Solar Flare ◽  
Solar Flares ◽  
Cosmic Ray ◽  
Flare Activity ◽  
Cosmic Ray Intensity ◽  
Cosmic Ray Modulation ◽  
Long Duration ◽  
Flare Index ◽  
Galactic Cosmic Ray

AbstractWe present here the results of the correlation analysis between the galactic cosmic ray intensity decrease p (as observed on Calgary neutron monitor station) and the occurence of SXR long-lasting (LDE-type) solar flares, represented by the LDE-type flare index FI. It is shown, that for the solar cycle with the lower monthly values of FI (the 21-st solar cycle) the correlation coefficient is slighter (about 0.4) comparing to the cycles with the higher LDE-type flare activity (about 0.6, in the 20-th and the 22-nd cycles).

Study on Solar Proton Events in the Sun - Induced Earth’s Magnetic Field Atmospheric Variations

2017 ◽  
Vol 3 (06) ◽  
Author(s):  
M. V. Subramanian ◽  
S. Jagadesan ◽  
K. Aruna ◽  
S. Pari ◽  
S. Deivamalar
Keyword(s):  
Magnetic Field ◽  
Solar Flare ◽  
Solar Proton ◽  
Proton Event ◽  
Dst Index ◽  
Data Centre ◽  
Sunspot Numbers ◽  
The Earth ◽  
Solar Proton Events ◽  
Ap Index

Estimation has been made for the most powerful solar proton events recorded in the Earth environment during 1976 - 2015. This study has been done in association with other related activities such as Sunspot numbers and Solar flare index, the Earth’s magnetic field variation H constant, Dst index, Ap index and Kp index data from Kyoto data centre and OMNI data centre. We found that proton flux occurred after two days indicate the Dst index, Ap index and Kp index and Earth’s magnetic field H constant variations. This study has been done in association with other related activities such as sunspot numbers, solar flare activities. We found that the proton event occurred within 25 to 29 days after the cyclone was formed in the earth atmosphere. Earth atmospheric climate also changed.

Diffusion of high-energy solar particles through interplanetary space

1968 ◽  
Vol 46 (10) ◽  
pp. S772-S775 ◽  
Author(s):  
I. Kondo ◽  
K. Fujimoto ◽  
K. Nagashima ◽  
H. Oda
Keyword(s):  
Magnetic Field ◽  
Lower Energy ◽  
Interplanetary Space ◽  
Cosmic Ray ◽  
High Energy ◽  
Maximum Density ◽  
Satellite Observations ◽  
Number Density ◽  
The Earth ◽  
Relativistic Particles

The effects of the interplanetary magnetic field on the propagation of solar cosmic-ray particles are studied. The presence of the quasi-stable magnetic field of garden-hose type found by satellite observations suggests that the movement of the particles along these lines of force is much easier than that perpendicular to them. The diffusion equation of the particles through such a medium is solved, and the number density of particles at the earth is computed for several values of parameters. The results of the computation concerning the dependence of the time of maximum density on the position of the source relative to the sun–earth line are compared with those obtained from observations. It is found that the diffusion coefficient perpendicular to the line of force is 1/10 to 1/20 of that parallel to the line for relativistic particles, while the ratio is 1/50 to 1/100 for lower-energy particles.

The Cosmic Ray Solar Flare Increase of 16 February 1984

1984 ◽  
Vol 5 (4) ◽  
pp. 593-594
Author(s):  
A. G. Fenton ◽  
K. B. Fenton ◽  
J. E. Humble
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Solar Flare ◽  
Cosmic Ray ◽  
Ground Level ◽  
Solar Proton ◽  
Solar Proton Events

Six solar proton events have been observed by ground level cosmic ray detectors so far during solar cycle 21, a little less than one per year. All of these have been much smaller than the giant events observed in solar cycle 19. As with many other aspects of solar activity, the reason for the differences from cycle to cycle remain unknown.

Determination of the solar-flare cosmic-ray rigidity spectrum using the worldwide neutron monitor network

1970 ◽  
Vol 48 (4) ◽  
pp. 419-431 ◽  
Author(s):  
R. A. R. Palmeira ◽  
R. P. Bukata ◽  
P. T. Gronstal
Keyword(s):  
Cosmic Rays ◽  
Solar Flare ◽  
Neutron Monitor ◽  
Cosmic Ray ◽  
Spectral Exponent ◽  
The Earth ◽  
Rigidity Spectrum

The determination of the rigidity spectrum of solar-flare-produced cosmic rays is examined. A method based on the ratio of relative enhancements observed at two stations sufficiently separated in latitude is discussed, and graphs are presented showing the expected ratio of enhancements as a function of the spectral exponent of the flare-produced cosmic rays for 6 pairs of stations. This method, which assumes that the cosmic-ray particles arrive at the earth isotropically, is then applied to the 28 January 1967 event during which this condition of isotropy is shown to exist. An extension of this method to the case of anisotropic arrival of solar cosmic-ray particles using the concept of variational coefficient is outlined.

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