Minimum Value of the Heliospheric Magnetic Field in 2008–2010, According to WIND and ACE Data

Abstract

Estimates are presented for the contribution from the magnetic fields of corotating regions of the interaction between fluxes of fast and slow wind to the measured heliospheric magnetic field (HMF) at 1 AU in the solar activity minimum of 2008–2010. A technique allowing such estimates to be made is considered, and the results from estimates made using data from the WIND and ACE spacecraft are presented. The contribution from the magnetic fields of corotating regions of interaction to the total field in the minimum of the 24th solar activity cycle is around 10%, and the minimum HMF intensity near the Earth in 2009 is 3.54 ± 0.11 nT. The magnetic fields of corotating regions of interaction play an important part in the modulation of galactic cosmic rays (GCRs). These fields affect HMF fluctuation spectra in the sector zone, altering the rigidity dependence of the GCR diffusion tensor and ultimately the GCR spectra in the heliosphere at particle energies of E < 10 GeV.