Observations of the Van Allen radiation regions during August and September 1959

Hoffman, R. A.

doi:10.1029/jz066i012p04003

Cited by 11 publications

(2 citation statements)

References 7 publications

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“…Bifurcation of the outer zone (i.e., two intensity peaks due to energetic electrons) was not observed in the first five months of Explorer 14 data presently under discussion. Bifurcation of the outer zone has been previously observed near the geomagnetic equatorial plane with instruments aboard Explorer 6 [Hoffman, 1961] and on Explorer 12 [Freeman, 1964] Figures 2, 3, and 4). Hence, it appears that such protons are markedly less sensitive to geomagnetic disturbances than are electrons (see Figure 4 in particular).…”

Section: The Above Sequence Of Phenomena Is Consistentmentioning

confidence: 57%

A study of charged particles in the Earth's outer radiation zone with explorer 14

Frank¹,

Allen²,

Hills³

1964

J. Geophys. Res.

100

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A comprehensive study of the intensities of electrons and protons near the equatorial plane in the earth's outer radiation zone is presented. The data were obtained with SUI equipment on Explorer 14 during the five‐month period October 1962 through February 1963. Emphasis is on the radial distribution of absolute intensities of protons and electrons and on the time variations of the energy spectrum and radial distribution of electrons. Typical omnidirectional intensities of electrons in the heart of the outer zone (L ∼ 4.0, on the equator) are: Jo(Ee > 40 kev) = 3 × 107(cm2 sec)−1 Jo(Ee > 230 kev) = 3 × 106(cm2 sec)−1 Jo(Ee > 1.6 Mev) = 3 × 105(cm2 sec)−1 The three‐point integral energy spectrum of electrons over the range 40 kev to 1.6 Mev is represented by E−1.0(±0.5) at L = 4.8 for most of the period of the present investigation except during short periods of low‐energy (Ee > 40 kev) electron enhancement. The gross temporal variation of the intensities of electrons increases markedly as L increases from 3.2 to 4.8 and at 4.8 is by factors of about 100 for Ee > 40 kev, about 10 for Ee > 230 kev, and about 100 for Ee > 1.6 Mev. A positive correlation between Kp daily sums and equatorial intensities of electrons Ee > 40 kev is demonstrated. Detailed time histories are given. Slow, inward radial motion of the distribution of energetic electrons Ee > 1.6 Mev with an apparent velocity of about 0.02Re/day is observed between radial distances of 3 and 4Re after poststorm enhancement of intensity. Typical omnidirectional intensities of protons Jo (Ep > 0.5 Mev) are 7 × 106 (cm2 sec)−1 near the equator for 2.8 < L < 3.6 and do not vary with time by more than a factor of 2 during the period of observation. Artificial radiation belts produced by the Soviet nuclear bursts at high altitudes during late October and early November 1962 are also detected, and their time decays are plotted.

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Section: The Above Sequence Of Phenomena Is Consistentmentioning

confidence: 57%

A study of charged particles in the Earth's outer radiation zone with explorer 14

Frank¹,

Allen²,

Hills³

1964

J. Geophys. Res.

100

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“…On the recovery phase the intensity and average electron energy increase and exceed their prestorm levels due to either injection of energetic electrons from the interplanetary medium into the trapping zone or some acceleration process connected with the geomagnetic disturbance. This phenomenological pattern was confirmed later by numerous observations of relativistic electron fluxes in the heart of the ORB [Arnoldy et al, 1960;Hoffman et al, 1962;Forbush et al, 1962]. Direct comparison of the electron fluxes in the ORB and in the interplanetary medium [Van Allen and Lin, 1960] shown that the ORB was developed over 2-day period after the storm maximum and it contained several thousand times the intensity of electrons that was present in the original solar plasma cloud before its arrival at the Earth.…”

Section: Introductionmentioning

confidence: 71%

Dependence of geosynchronous relativistic electron enhancements on geomagnetic parameters

Дмитриев

Chao

2003

J. Geophys. Res.

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[1] Relativistic electron fluxes observed in geosynchronous orbit by GOES-8 in 1997 to 2000 were considered as a complex function of geomagnetic indices PC, Kp, and Dst, as well as parameters of the magnetosphere size, subsolar Rs, and terminator Rf magnetopause distances. A geosynchronous relativistic electron enhancement (GREE) is determined as daily maximal electron flux exceeding the upper root mean square deviation (RMSD) threshold of about 1500 (cm 2 s sr) À1 . Comparison analysis of the GREE dynamics and geomagnetic conditions on the rising phase of current solar cycle revealed suppression of the relativistic electron enhancements by substantially increased strong geomagnetic activity in the solar maximum. Statistical consideration of a relationship between the GREEs and the geomagnetic parameters showed that the most important parameters controlling the geosynchronous relativistic electron enhancements were 4-day averaged Kp index, PC index, and magnetopause termination distance Rf, delayed on 3 and 14 hours, respectively. Relatively high averaging time for Kp was explained by the cumulative effect of substorm energy release in a gradual mechanism accelerating the relativistic electrons in the magnetosphere. Very short time delay for PC index was interpreted as intensification of a fast acceleration mechanism producing the GREEs during severe geomagnetic storms. Substantial increase of the PC index (PC > 5) was found to be a sufficient condition for GREE occurrence. The fast response of the geosynchronous relativistic electron fluxes on the magnetosphere compression was explained by drift losses of the energetic electrons at the magnetopause, which approaches the Earth during geomagnetic storms.

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Geomagnetism

1970

Annals of the International Geophysical Year

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Observations of the Van Allen radiation regions during August and September 1959

Cited by 11 publications

References 7 publications

A study of charged particles in the Earth's outer radiation zone with explorer 14

A study of charged particles in the Earth's outer radiation zone with explorer 14

Dependence of geosynchronous relativistic electron enhancements on geomagnetic parameters

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