Space Sciences

Heliospheric modulation of galactic cosmic rays during grand solar minima: Past and future variations

  1. M. J. Owens1,*,
  2. I. Usoskin2,3,
  3. M. Lockwood1

Article first published online: 5 OCT 2012

DOI: 10.1029/2012GL053151

Issue

Geophysical Research Letters

Geophysical Research Letters

Volume 39, Issue 19, 16 October 2012

Additional Information

How to Cite

Owens, M. J., I. Usoskin, and M. Lockwood (2012), Heliospheric modulation of galactic cosmic rays during grand solar minima: Past and future variations, Geophys. Res. Lett., 39, L19102, doi:10.1029/2012GL053151.

Author Information

  1. 1

    Space Environment Physics Group, Department of Meteorology, University of Reading, Reading, UK

  2. 2

    Oulu Unit, Sodankylä Geophysical Observatory, University of Oulu, Oulu, Finland

  3. 3

    Department of Physics, University of Oulu, Oulu, Finland

*Corresponding author: M. J. Owens, Space Environment Physics Group, Department of Meteorology, University of Reading, Earley Gate, PO Box 243, Reading RG6 6BB, UK. (m.j.owens@reading.ac.uk)

Publication History

  1. Issue published online: 5 OCT 2012
  2. Article first published online: 5 OCT 2012
  3. Manuscript Revised: 4 SEP 2012
  4. Manuscript Accepted: 4 SEP 2012
  5. Manuscript Received: 16 JUL 2012

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Keywords:

  • Maunder Minimum;
  • heliospheric magnetic field;
  • solar variability;
  • sunspot number

[1] Galactic cosmic ray flux at Earth is modulated by the heliospheric magnetic field. Heliospheric modulation potential, Φ, during grand solar minima is investigated using an open solar flux (OSF) model with OSF source based on sunspot number, R, and OSF loss on heliospheric current sheet inclination. Changing dominance between source and loss means Φ varies in- (anti-) phase with R during strong (weak) cycles, in agreement with Φ estimates from ice core records of10Be concentration, which are in-phase during most of the last 300 years, but anti-phase during the Maunder Minimum. Model results suggest “flat” OSF cycles, such as solar cycle 20 result from OSF source and loss terms temporarily balancing throughout the cycle. Thus even if solar activity continues to decline steadily, the long-term drop in OSF through SC21 to SC23 may plateau during SC24, though reemerge in SC25 with the inverted phase relation.

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