Solar Physics

, Volume 238, Issue 2, pp 391–404

Global Heliospheric Parameters and Cosmic-Ray Modulation: An Empirical Relation for the Last Decades


    • Department of Physical SciencesUniversity of Oulu
  • K. Mursula
    • Department of Physical SciencesUniversity of Oulu
  • I. G. Usoskin
    • Sodankylä Geophysical Observatory (Oulu Unit)University of Oulu
  • G. A. Kovaltsov
    • Ioffe Physical-Technical Institute

DOI: 10.1007/s11207-006-0233-z

Cite this article as:
Alanko-Huotari, K., Mursula, K., Usoskin, I.G. et al. Sol Phys (2006) 238: 391. doi:10.1007/s11207-006-0233-z


We study empirical relations between the modulation of galactic cosmic rays quantified in terms of the modulation potential and the following global heliospheric parameters: the open solar magnetic flux, the tilt angle of the heliospheric current sheet, and the polarity of the heliospheric magnetic field. We show that a combination of these parameters explains the majority of the modulation potential variations during the neutron monitor era 1951 – 2005. Two empirical models are discussed: a quasi-linear model and a model assuming a power-law relation between the modulation potential and the magnetic flux. Both models describe the data fairly well. These empirical models provide a simple tool for evaluating various cosmic-ray related effects on different time scales. The models can be extended backwards in time or used for predictions, if the corresponding global heliospheric variables can be independently estimated.

Copyright information

© Springer Science + Business Media, Inc. 2006