Reversal of the cosmic ray density gradient perpendicular to the ecliptic plane

Abstract

Annual averages of the diurnal variation in cosmic ray intensity for neutron monitors in Deep River and Oulu and underground muon telescopes in Bolivia and at Embudo and Socorro, New Mexico, have been determined as a function of the sense of the interplanetary magnetic field for the years 1965–1975. These data point to a cosmic ray density gradient, perpendicular to the ecliptic plane, pointing southward prior to 1969 and changing to a northward pointing gradient after the reversal of the sun's polar magnetic field in 1969–1971. This result supports numerical calculations for the prereversal and postreversal field configurations at intermediate and high cosmic ray rigidities.