The Time Variations of the Cosmic Ray Intensity

Quenby, J. J.

doi:10.1007/978-3-642-46079-1_5

Cited by 17 publications

(9 citation statements)

References 74 publications

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“…A number of expositions of the processes that are involved in the propagation of cosmic rays through the solar-controlled interplanetary medium have appeared in the literature. Reviews of the physics of the solar wind and of its role in cosmic ray modulations and anisotropies contain analyses and references to the many significant advances that have brought the subject to its present state of sophistication [Parker, 1963[Parker, , 1969Jokipii, 1966Jokipii, , 1971Rodof, 1966;Desder, 1967;Quenby, 1967;Axford, 1968;Fisk, 1969;Gleeson, 1972]. To set the stage for the discussion that follows, we will briefly summarize the theoretical framework that incorporates all of the effects whereby the sun governs the motions of galactic and solar cosmic rays.…”

Section: Cosmic Ray Modulations and Anisotropies Theoretical Modelsmentioning

confidence: 99%

The Sun and cosmic rays

Pomerantz¹,

Duggal²

1974

Reviews of Geophysics

102

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Solar phenomena produce cosmic ray intensity variations over a wide range of time scales. The observed flux is modulated and rendered anisotropic as the particles propagate in the solar wind, and it is occasionally enhanced by the sporadic emission of solar cosmic rays. Both quasi‐static phenomena (the long‐term omnidirectional intensity variation and the steady state diurnal anisotropy) and transient fluctuations (disturbed daily variation and Forbush decrease) as well as the spatial distribution of solar flare particles are represented by a theoretical model that prescribes the role of the several solar‐controlled parameters that characterize the electromagnetic properties of the interplanetary medium. Considerable information concerning the ambient conditions has been obtained with spacecraft. However, the in situ measurements are confined to a limited region near the ecliptic plane. Consequently, in some cases, theoretical predictions based upon them are not in accord with observations of cosmic ray intensity variations. Thus the modulations and anisotropies must be treated in a three‐dimensional framework. It is therefore reasonable to attempt to deduce the properties of the relevant inaccessible regions of the heliosphere from observations of the sun itself. These properties can be determined by relating the various cosmic ray phenomena to changes during a solar cycle and from one cycle to another. To this end, data covering at least two solar cycles are studied to determine the solar cycle dependence of the following effects: long‐term variations in the omnidirectional intensity, Forbush decreases, solar diurnal variations, and solar cosmic ray events (ground level enhancement and polar cap absorption).

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Section: Cosmic Ray Modulations and Anisotropies Theoretical Modelsmentioning

confidence: 99%

The Sun and cosmic rays

Pomerantz¹,

Duggal²

1974

Reviews of Geophysics

102

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“…The model assumes that convection is the dominant transport mechanism and is consistent with particles originating at the sun. It has been pointed out by several authors [e.g., Parker, 1965;Quenby, 1966Quenby, , 1967Fisk and Ax•ord, 1968;Forman, 1968Forman, , 1970bForman, , 1971Ax[ord, 1970] that energetic particles released from solar flares are likely to undergo substantial deceleration if the diffusion velocity is comparable to or less than the solar wind speed. Here we consider steady emission and use results that are valid asymptotically in order to make comparisons with observations.…”

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confidence: 99%

Low-energy cosmic rays near Earth

Gleeson¹,

Krimigis²,

Axford³

1971

J. Geophys. Res.

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Observations of protons with kinetic energy >0.31 Mev in interplanetary space during quiet times made from the spacecraft Explorer 33 show that there is an anisotropy of ∼15%, the maximum flux being directed approximately radially outward from the sun. This observation, and the corresponding radial gradient results reported by S. M. Krimigis, are shown to be in very good agreement with those expected from a model in which the observed protons are convected outward at the solar wind speed. It is concluded that these particles have come from an interior region and that the most probable source is the sun, but the possibility that they are of galactic origin, although remote, cannot be positively excluded.

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“…The galactic cosmic radiation is modulated by the sun resulting in three major-classes of 126,127 time variations…”

Section: B Temporal Variationsmentioning

confidence: 99%

Charged Particle Radiation Environment in Synchronous Orbit

Stanley¹,

Ryan²

1968

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The present state of knowledge of the charged particle radiation environment in synchronous orbit is described. The composition, intensity, energy spectrum and temporal variations of the radiation are listed. The data are based on measurements on board satellites in elliptical and in synchronous orbits, including the results from the electron telescope on board LES-4, whose apogee is in synchronous orbit. The radiation consists mainly of trapped electrons and low energy protons, but solar flare protons also make a significant contribution. The time-averaged data are given in a form useful for predicting the long-term radiation environment to which a satellite in synchronous orbit would be exposed.

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The Time Variations of the Cosmic Ray Intensity

Cited by 17 publications

References 74 publications

The Sun and cosmic rays

The Sun and cosmic rays

Low-energy cosmic rays near Earth

Charged Particle Radiation Environment in Synchronous Orbit

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