Convection in the Magnetosphere-Ionosphere System: A Multimission Survey of Its Response to IMF By Reversals

Abstract

Past studies have demonstrated that the interplanetary magnetic field (IMF) By component introduces asymmetries in the magnetosphere-ionosphere (M-I) system, though the exact timings involved are still unclear with two distinct mechanisms proposed. In this study, we statistically analyze convective flows from three regions of the M-I system: the magnetospheric lobes, the plasma sheet, and the ionosphere. We perform superposed epoch analyses on the convective flows in response to reversals in the IMF By orientation, to determine the flow response timescales of these regions. We find that the lobes respond quickly and reconfigure to the new IMF By state within 30–40 min. The plasma sheet flows, however, do not show a clear response to the IMF By reversal, at least within 4 hr postreversal. The ionospheric data, measured by the Super Dual Auroral Radar Network (SuperDARN), match their counterpart magnetospheric flows, with clear and prompt responses at ≥75° magnetic latitude (MLAT) but a less pronounced response at 60–70 MLAT. We discuss the potential implication of these results on the mechanisms for introducing the IMF By component into the M-I system.