title: Polar coronal holes and cosmic-ray modulation.
abstract: A comparison of the size of polar coronal holes with the cosmic-ray intensity observed during the most recent sunspot cycle shows close correspondence. This lends support to recent suggestions that the well-known sunspot-cycle modulation of cosmic rays is a three-dimensional effect, probably related to the global character of the interplanetary magnetic field.
authors.forename: A J
authors.initials: AJ
authors.lastname: Hundhausen
authors.forename: D G
authors.initials: DG
authors.lastname: Sime
authors.forename: R T
authors.initials: RT
authors.lastname: Hansen
authors.forename: S F
authors.initials: SF
authors.lastname: Hansen