Cosmic-ray anisotropy in the north–south direction

• Published in: Canadian Journal of Physics
• Main Authors: Murakami, K., Kudo, S.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1968
• Subjects: General Physics and Astronomy; Arctic; Antarctic; The Antarctic; Wilcox; Antarc*
• Online Access: http://dx.doi.org/10.1139/p68-363; http://www.nrcresearchpress.com/doi/pdf/10.1139/p68-363

For the study of a cosmic-ray anisotropy in the north–south direction, the day-to-day variation of the difference (N–S) of cosmic-ray neutron intensities between the arctic and the antarctic was examined with respect to solar rotations. Harmonic analysis on the variation of the intensity difference shows the existence of a recurrent variation with half the period of a solar rotation. Such a recurrent variation is closely connected with the rapid phase changes of the cosmic-ray diurnal variation during a solar rotation. Regarding the sectored structure of solar wind reported by Wilcox and Ness, the intensity difference (N–S) increases when the earth is passing near a boundary from the (+) sector into the (−) sector, while it decreases near the other boundary. This N–S anisotropy of cosmic rays seems to be caused by the transitional change of cosmic-ray trajectories near the sector boundary and by the spatial distribution of cosmic-ray flux.