The two IMF orientation factors in solar-wind/magnetosphere coupling functions used in this paper: (blue) sin⁴(θ_GSM/2), where θ_GSM is the IMF clock angle in the GSM frame, and (red) [B_S]_GSM/B_YZ, where is the halfwave-rectified southward field in the GSM frame and is the magnitude of the field in the Y-Z plane (which is the same for the GSE, GSEQ and GSM frames). Both are plotted as a function of .