Study of tri-diurnal variation of galactic cosmic radiation
Journal Article
·
· J. Geophys. Res.; (United States)
Using the experimental data of the high counting rate neutron and meson monitors, the solar tri-dirunal anisotropy of galactic cosmic radiation has been investigated for the period 1962-79. The enhancement of the average tri-diurnal amplitude observed by all the detectors during 1973-75 provides sufficient signal to noise ratio to obtain a power law rigidity spectrum exponent roughly-equal1. The tri-diurnal amplitude varies as cos/sup 3/ lambda, where lambda is the effective asymptotic latitude of the detector. The annual average tridiurnal amplitude shows a significant positive correlation with the semi-diurnal amplitude for the period 1968-79. The correlation, however, is poor for the earlier period 1962--67, which may be due to the presence of significant modulation of semi-diurnal anisotropy with periods of 22-year sunspot magnetic cycle. An analysis using groups of days with high and low solar wind speed shows greater amplitude of both the tri-diurnal and semi-diurnal waves for the group of days with high wind speed. This result coupled with the observation of a factor of 2 increase in both amplitudes during 1973--75, a period when high speed solar wind streams were prevalent, suggests that solar polar coronal holes may influence both the solar tri-diurnal and semi-dirunal variation of galactic cosmic ray intensity.
- Research Organization:
- Herzberg Institute of Astrophysics, National Research Council of Canada, Ottawa, Canada K1A OR6
- OSTI ID:
- 5885450
- Journal Information:
- J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 86:A12; ISSN JGREA
- Country of Publication:
- United States
- Language:
- English
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