Coronal imprints in the heliospheric plasma and magnetic fields at the Earth's orbit during the last three solar minima

Abstract

The periods 1975–1977, 1985–1987 and 1995–1997 were selected between pivot points of the solar cycles to analyze available spacecraft data for three successive solar minima. The mean values of the solar wind velocity, dynamic pressure, and temperature are decreasing during each indicated time interval. All variations are of several 0.1. The interplanetary magnetic field is minimal at solar minima. There is no strong difference between solar wind and interplanetary magnetic field parameters as well as solar activity indices for these solar cycles. Nevertheless, the proton cosmic ray intensities and spectra during these especially quiet periods possibly show the remarkable 22-year variation with the minimal proton fluxes in 1985–1987.