The 27 day average solar wind/interplanetary parameters from 1968 January 1 to 2020 October 31. (a) Sunspot number. (b) Mean solar polar field strength. (c) HCS Tilt angle. (d) IMF magnitude B and its root mean square δB. (e) Solar wind speed V_sw. (f) Solar wind dynamic pressure P_d. (g) Pressure-corrected NM count rates (normalized to the solar minimum P_23/24 and multiplied by arbitrary factors to distinguish different stations). The shown magnetic field polarity in panel (b) corresponds to that at the northern pole. The vertical dashed line denotes the epoch of solar minimum.