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Variation with a period of two solar cycles in the cosmic-ray diurnal anisotropy and the superposed variations correlated with magnetic activity

1969; American Geophysical Union; Volume: 74; Issue: 14 Linguagem: Inglês

10.1029/ja074i014p03451

2156-2202

Scott E. Forbush,

Geophysics and Gravity Measurements

Journal of Geophysical Research (1896-1977)Volume 74, Issue 14 p. 3451-3468 Variation with a period of two solar cycles in the cosmic-ray diurnal anisotropy and the superposed variations correlated with magnetic activity Scott E. Forbush, Scott E. ForbushSearch for more papers by this author Scott E. Forbush, Scott E. ForbushSearch for more papers by this author First published: 1 July 1969 https://doi.org/10.1029/JA074i014p03451Citations: 47AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Abstract Annual means of the diurnal anisotropy from 1937 to 1967 are shown to result from the addition of two distinct diurnal components. One component, with maximum in the asymptotic direction 128° east of the sun, contains a well-determined wave, W, with a period of two solar cycles. W passes through zero in 1958 when the sun's poloidal field reversed. The remaining component with W eliminated, has its maximum in the asymptotic direction 90° east of the sun. Annual means of this component, with maximum at 18.0 hours local asymptotic time, are well correlated (r = +0.75) with magnetic activity and determine a solar cycle variation with minimum near sunspot minimum and amplitude about two-thirds that of W. These results derive from a statistical investigation of the variability of annual means of the diurnal variation from ion-chamber data at Cheltenham-Fredericksburg, Huancayo, and Christchurch. The absolute, or total, diurnal anisotropy and the atmospheric diurnal temperature effect are in reasonable agreement with those derived independently through a comparison between the diurnal anisotropy from ion-chamber data and from Simpson's 1953–1966, IGY neutron monitor data at Huancayo. References Abels, J. G., K. G. McCracken, U. R. Rao, The semidiurnal anisotropy of the cosmic radiation, Proc. Intern. Conf. Cosmic Rays, London, 1, 208, 1965. Axford, W. I., The modulation of galactic cosmic rays in the interplanetary medium, Planetary Space Sci., 13, 115, 1965. Babcock, HaroldD., The sun's polar magnetic field, Astrophys. J., 130, 364, 1959. Bartels, J., Random fluctuations, persistence, and quasi-persistence in geophysical and cosmical periodicities, Terrest. Magnetism Atomospheric Elec., 40, 1, 1935. Duggal, S. P., M. A. Pomerantz, ScottE. Forbush, Long-term variation in the magnitude of the diurnal anisotropy of cosmic rays, Nature, 214, 154, 1967. Forbush, S. E., On diurnal variation in cosmic-ray intensity, Terrest. Magnetism Atmospheric Elec., 42, 1, 1937. Forbush, S. E., Barometric pressure corrections to the cosmic-ray ionization at Huancayo and the change in apparent ion-chamber sensitivity after about 1955,to be included in Cosmic-Ray Results,Carnegie Inst. Wash.Publ. 175, vol. 22(in publication), 1968. Forbush, ScottE., Liselotte Beach, The absolute geomagnetic field of the equatorial ring current, Carnegie Inst. Wash. Yr. Book, 65, 28–36, 1967. Forbush, ScottE., S. P. Duggal, MartinA. Pomerantz, Monte Carlo experiment to determine the statistical uncertainty for the average 24-hour wave derived from filtered and unfiltered data, Can. J. Phys., 46, S985, 1968. Forbush, ScottE., D. Vénkatesan, Diurnal variation in cosmic-ray intensity, 1937-1959, at Cheltenham (Fredericksburg), Huancayo, and Christchurch, J. Geophys. Res., 65, 2213, 1960. McCracken, K. G., andU. R. Rao, A survey of the diurnal anisotropy,Proc. Intern. Conf. Cosmic Rays,London, 1, 213,1965. Parker, E. N., Dynamics of the interplanetary gas and magnetic fields, Astrophys. J., 128, 664, 1958. Parker, E. N., Theory of streaming of cosmic rays and the diurnal variations, Planetary Space Sci., 12, 735, 1964. Thambyahpillai, T., H. Elliot, World wide changes in the phase of the cosmic-ray solar daily variation, Nature, 171, 918, 1953. Uhler, H. S., Method of least squares and curve fitting, J. Opt. Soc. Am., 7, 1043, 1923. Wilcox, J. M., N. F. Ness, Quasi-stationary corotating structure in the interplanetary medium, J. Geophys. Res., 70, 5793, 1965. Citing Literature Volume74, Issue14Space Physics1 July 1969Pages 3451-3468 ReferencesRelatedInformation