Coronal holes in the long-term modulation of cosmic rays

Abstract

Long term cosmic ray variations in the heliosphere in cycles 21–24 are described using the multiparametric model, including characteristics of solar activity. Long-term observations of the cosmic ray intensity, global solar magnetic field characteristics, and characteristics taking into account sporadic solar activity are the initial data for modeling cosmic ray variations. Data on intensity have been obtained from observations at the global ground network of neutron monitors and stratospheric sounding. The characteristics of the regions with an open magnetic field (coronal holes) have been introduced into the model in order to improve the description of long-term variations. The location (latitude), area, and magnetic flux of coronal holes have been used as parameters of this solar activity type manifestation. The modulation has been modeled for the entire studied period (1976–2012) and independently for periods with identical global solar magnetic field directions with regard to the cosmic ray variation delay relative to variations in the solar activity characteristics. It has been shown that the accuracy of long-term variation description improves when coronal hole characteristics are taken into account.