Abstract

A new reconstruction of the heliospheric modulation potential for galactic cosmic rays is presented for the neutron monitor era, since 1951. The new reconstruction is based on an updated methodology in comparison to previous reconstructions: (1) the use of the new-generation neutron monitor yield function; (2) the use of the new model of the local interstellar spectrum, employing in particular direct data from the distant missions; and (3) the calibration of the neutron monitor responses to direct measurements of the cosmic ray spectrum performed by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) spaceborne spectrometer over 47 time intervals during 2006–2010. The reconstruction is based on data from six standard NM64-type neutron monitors (Apatity, Inuvik, Kergulen, Moscow, Newark, and Oulu) since 1965 and two International Geophysical Year-type ground-based detectors (Climax and Mount Washington) for 1951–1964. The new reconstruction, along with the estimated uncertainties is tabulated in the paper. The presented series forms a benchmark record of the cosmic ray variability (in the energy range between 1 and 30 GeV) for the last 60 years and can be used in long-term studies in the fields of solar, heliospheric, and solar-terrestrial physics.

Plain Language Summary

Solar magnetic activity modulates the flux of energetic galactic cosmic rays bombarding Earth. A newly revised method for a quantitative assessment of the cosmic ray modulation parameter using data from the ground-based network of neutron monitors is presented. The new reconstruction employs a calibration of the ground-based data to the spaceborne direct measurements during a period of 2006–2010. The presented reconstructions form a benchmark record of the cosmic ray variability (in the energy range between 1 and 30 GeV) for the last 60 years and can be used in long-term studies in the field of solar, heliospheric, and solar-terrestrial physics.