Variations with time of values over half-year intervals (centred on the equinoxes) for the 1996–2018 interval used in Figure A1. (a). The sunspot number, R. (b) The polar field strength from Wilcox Solar Observatory (WSO) magnetograms, B_p, where red/blue is for the north/south solar pole, respectively. (c) The fraction of time f that the IMF has [B_Y]_GSEQ > 0 polarity (mauve line with open circles) and [B_Y]_GSEQ < 0 polarity (green line with solid triangles). (d) The number of 1-minute samples of [B_Y]_GSEQ in bins 1 nT wide and 6-month intervals centred on the equinoxes, N to as a function of date and [B_Y]_GSEQ (plotted on a logarithmic colour scale to reveal the tails of the distributions as well as the peaks). The vertical grey lines mark the polarity reversals of the solar polar fields