Access of solar protons into the polar cap: A persistent north-south asymmetry

Before the magnetic storm sudden commencement during the November 2, 1967, solar particle event, the access of 1.2- to 40-Mev protons into the high-latitude portion of the northern polar region was delayed by ∼20 hours. At the same time the access delay for 10- to 40-Mev protons was ≲1 hour in the southern polar region and at middle northern latitudes. The implications of the north-south asymmetry are discussed.