Relation of the Cosmic Radiation to Geomagnetic and Heliophysical Activities

Abstract

Relations between 28-day fluctuations of intensity of the cosmic radiation and both terrestrial magnetic activity and sunspot areas were investigated. Definite pulses, both in the magnetic character and in sunspot areas, were found to be associated with the primary pulses in the cosmic radiation at Boulder, obtained by Chree's "superposedepoch" method. They were in general phase opposition to the cosmic-ray pulses, but the tip of the magnetic-character pulse preceded the tip of the opposite cosmic-ray pulse by one day; the lead was three or four days in the case of the opposed sunspot pulses. Similar relations were not found among secondary pulses, although a 34-day periodicity in sunspot-area pulses referred to days selected on the basis of cosmic-ray intensity was displayed. Direct application of Chree's method to the magnetic character and sunspot areas, individually, indicated a 27-day periodicity in the former and a 34-day periodicity in the latter. A second method of investigation, used by Graziadei, Kolhörster, and others, was also employed. This yielded results in some respects contradictory to the first. In particular, it indicated 27-day fluctuations in sunspot areas in phase with the cosmic-ray fluctuations and out of phase with changes in magnetic character. However, it also indicated the 34-day periodicity in sunspot areas for the period of the investigation was more pronounced than the 27-day periodicity. Among other possibilities, the possible effects of sunspots through the agency of their magnetic fields were considered.