Particle Dynamics at the Synchronous Orbit

  • J. W. FreemanJr.
  • J. J. Maguire
Conference paper
Part of the Astrophysics and Space Science Library book series (ASSL, volume 10)


A low-energy charged particle detector has been flown aboard the geostationary ATS-1 satellite. A preliminary study of the data has revealed large local time variations in the particle fluxes observed during geomagnetically disturbed times. The salient features of the observed variations are: (1) During periods of moderate magnetic activity a high particle flux is seen near local midnight. This flux shows a strong pre/post-midnight asymmetry with the particle intensities being higher in the midnight to dawn quadrant. (2) During periods of high magnetic activity the enhanced particle flux distribution broadens out in local time to cover a large fraction of the night-side portion of the synchronous orbit. The pre/post-midnight asymmetry is generally still present but less striking. (3) During periods of enhanced magnetic activity the local time distribution of the particle fluxes shows a remarkable similarity to the local time distribution of high-latitude magnetic substorm activity.

We suggest that the observed particle distribution is indicative of an influx of energetic plasma from the magnetospheric tail. Implications relating to magnetic storm models are discussed.

In the final section of this paper the world-wide magnetic storm of January 13–14, 1967 is analyzed. Data are presented which indicates a magnetospheric boundary crossing and the anisotropic injection of a cloud of monoenergetic protons. It is suggested that this localized plasma cloud maintains its identity through at least three longitudinal drift periods.


Magnetic Storm Particle Flux Particle Dynamic Synchronous Orbit Sudden Impulse 
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  1. Axford,W. I. and Hines, C. O.: 1961, ‘A Unifying Theory of High-Latitude Geophysical Phenomena and Geomagnetic Storms’, Can. J. of Phys. 39, 1433–1464.MathSciNetADSCrossRefGoogle Scholar
  2. Axford, W. I., Petschek, H. E., and Siscoe, G. L.: 1965, ‘The Tail of the Magnetosphere’, J. Geophys. Res. 70, 1231–1236.ADSzbMATHCrossRefGoogle Scholar
  3. Cummings, W. D. and Coleman, Jr., P. J.: 1967, ‘Simultaneous Magnetic Field Variations at the Earth’s Surface and at the Synchronous, Equatorial Distance’, Conjugate Point Symposium, June.Google Scholar

Copyright information

© D. Reidel Publishing Company, Dordrecht, Holland 1968

Authors and Affiliations

  • J. W. FreemanJr.
    • 1
  • J. J. Maguire
    • 1
  1. 1.Dept. of Space ScienceRice UniversityHoustonUSA

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