Abstract
The cosmic-ray intensity during the 18th and 19th solar cycles is examined in the light of Gnevyshev's suggestion of the presence of two maxima in each solar cycle. The 18th solar cycle (1944–54) has two prominent and widely separated cosmic-ray minima corresponding in phase with the two maxima in Bartel's Ap index. For the 19th solar cycle the existence of two minima is less prominent than for the 18th solar cycle. The maximum at higher solar latitudes is more effective in reducing cosmic-ray intensity than the maximum at the lower latitudes. Ap, however, has a larger maximum during the lower latitude solar maximum. A relation between Ap and cosmic-ray intensity is obtained. This relationship is shown to be consistent with Parker's solar-wind theory of the modulation of cosmic rays.
Similar content being viewed by others
References
Antalova, H. and Gnevyshev, M. M.: 1965, Astron. Zh. 42, N2, 253.
Balasubrahmanyan, V. K., Boldt, E., and Palmeira, R. A. R.: 1967, J. Geophys. Res. 72, 27.
Balasubrahmanyan, V. K., Hagge, D. E., and McDonald, F. B.: 1968, Canadian J. Phys. 46, S887.
Dorman, I. V. and Dorman, L. I.: 1967, J. Geophys. Res. 67, 1513.
Durgaprasad, N., Fichtel, C. E., and Guss, D. E.: 1967, J. Geophys. Res. 72, 2765.
Fan, C. Y., Gloeckler, G., and Simpson, J. A.: 1965, in Proc. Intern. Conf. Cosmic Rays, London, vol. I, p. 380.
Forbush, S. E.: 1958, J. Geophys. Res. 63, 651.
Gloeckler, G. and Jokipii, J. R.: 1967, Astrophys. J. Letters 148, L41.
Gnevyshev, M. N.: 1967, Solar Phys. 1, 107.
Hatton, C. J., Marsden, P. L., and Willetts, A.: 1967, in: Proc. Intern. Conf. Cosmic Rays, Calgary.
Lockwood, J. A. and Webber, W. R.: 1967, J. Geophys. Res. 72, 5977.
McCRacken, K. G. and Rao, U. R.: 1966, Planetary Space Sci. 14, 649.
Neher, N. V.: 1962, J. Phys. Soc. Japan 17, Suppl. A2, 492.
Ormes, J. F. and Webber, W. R.: 1968, J. Geophys. Res. 732, 422.
Parker, E. N.: 1963, Interplanetary Dynamical Process, (Interscience), John Wiley, New York.
Roelof, E. C.: 1966, Ph.D. Thesis, University of California.
Simpson, J. A.: 1963, in Proc. Intern. Conf. Cosmic Rays, Jaipur, vol. II, p. 155.
Simpson, J. A. and Wang, J. R.: 1967, Astrophys. J. 149, L73.
Snyder, C. S., Neugebauer, M., and Rao, U. R.: 1963, J. Geophys. Res. 68, 6361.
Webber, W. R.: 1967, in Proc. Intern. Conf. Cosmic Rays, Calgary, Part A, p. 146.
Wilcox, J. M., Schatten, K., and Ness, N. F.: 1967, J. Geophys. Res. 72, 19.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Balasubrahmanyan, V.K. Solar activity and the 11-year modulation of cosmic rays. Sol Phys 7, 39–45 (1969). https://doi.org/10.1007/BF00148403
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00148403