Quantifying the Effects of Solar Wind Fluctuations on the Solar Wind‐Magnetosphere Interaction

Abstract Ala‐Lahti et al. (2024, https://doi.org/10.1029/2024GL112922 ) present results from a global magnetohydrodynamic simulation of a single geomagnetic substorm for four scenarios: the original solar wind conditions, smoothed low‐frequency solar wind conditions, constant solar wind conditions with a boxcar averaged north/south component of the interplanetary magnetic field (IMF), and the boxcar‐averaged scenario with ultra‐low‐frequency (ULF) fluctuations. Smoothed (<1 mHz) solar wind parameters capture the bulk of the interaction, boxcar averaging reduces the energy flow through the system by 15%–40%, and ULF fluctuations (2–8 mHz) only enhance interactions by 5%–15%. From this, we conclude that low‐frequency plasma and magnetic field variations dominate the interaction. Further global simulations and observational studies of different events will be needed to determine the significance of intrinsic magnetopause and magnetotail instabilities (rather than directly driven interplanetary magnetic field fluctuations). They will also be needed to generalize these results for the full range of solar wind and geomagnetic conditions.