On Diurnal Variation in Cosmic-Ray Intensity

  1. James A. Van Allen
  1. S. E. Forbush

Published Online: 20 MAR 2013

DOI: 10.1029/SP037p0119

Cosmic Rays, the Sun and Geomagnetism: The Works of Scott E. Forbush

Cosmic Rays, the Sun and Geomagnetism: The Works of Scott E. Forbush

How to Cite

Forbush, S. E. (1993) On Diurnal Variation in Cosmic-Ray Intensity, in Cosmic Rays, the Sun and Geomagnetism: The Works of Scott E. Forbush (ed J. A. Van Allen), American Geophysical Union, Washington, D. C.. doi: 10.1029/SP037p0119

Publication History

  1. Published Online: 20 MAR 2013
  2. Published Print: 1 JAN 1993

ISBN Information

Print ISBN: 9780875908335

Online ISBN: 9781118667996

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Keywords:

  • Cosmis ray variations;
  • Solar activity;
  • Geomagnetism

Summary

Cosmic-ray data from precision cosmic-ray meter records obtained at Cheltenham, Maryland, for 273 complete days during April 1935 to October 1936 are subjected to rigorous statistical analysis. The results indicate that the real barometric coefficient does not change from hour to hour or from month to month. It is shown that the barometric coefficient obtained at this station is in good agreement with certain results obtained from altitude-intensity curves. It is furthermore shown, in two independent ways, that there is no indication of any external air-temperature effect upon the recorded intensity. Finally, the data have been subjected to modern statistical methods which provide an objective measure for the probability that the observed diurnal-variation is real. The results indicate, for the period covered by this analysis, a physically significant 24-hour wave in apparent cosmic-ray intensity, with an amplitude of 0.17 per. cent of the total intensity having its maximum at about 11h, 75° west meridian mean time.