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Simultaneous measurements of F‐region neutral winds near 250 km and topside field‐aligned interhemispheric plasma flow near 600 km, made by the ionospheric connections satellite, allow the connection between these parameters to be observationally established for the first time. The largest variations in the topside plasma flows are seen as a function of season and are shown to depend on trans‐equatorial neutral winds near the F peak in a manner that is essentially the same during the daytime and the nighttime for the solar minimum conditions that prevail in 2020. This finding is consistent with established principles of a servo model of the ionosphere for which both production and loss rates in the topside are specified by the O/N2ratio at the F‐peak height. The intermediate relationships, describing how the neutral wind influences the F‐peak height and how the O+plasma pressure gradient across the equator influences the interhemispheric plasma flow are also investigated and found to be consistent with expectations. Neutral winds in the upper atmosphere apply collisional forces to the charged particles that produce motions parallel and perpendicular to the magnetic field. Motions parallel to the magnetic field influence the distribution of charged particle pressure and thus change the plasma motion everywhere along the magnetic field. Simultaneous measurements of the neutral winds and the plasma motions at remote locations connected by the magnetic field allow the relationships between these quantities to be observationally established for the first time. These relationships show the direct relationships between the meridional winds near 250 km, the peak height of the ionospheric density and the field‐aligned interhemispheric plasma transport velocity at the apex of the magnetic field near 600 km. Meridional winds near the F‐peak directly drive F‐peak height and topside field‐aligned interhemispheric plasma flowsMeridional wind across the magnetic equator at 250 km is linearly related to field‐aligned plasma flow across the magnetic equator at 600 kmIonospheric Connections satellite provides the first simultaneous observations of F‐region winds and topside field‐aligned interhemispheric plasma flows Meridional winds near the F‐peak directly drive F‐peak height and topside field‐aligned interhemispheric plasma flows Meridional wind across the magnetic equator at 250 km is linearly related to field‐aligned plasma flow across the magnetic equator at 600 km Ionospheric Connections satellite provides the first simultaneous observations of F‐region winds and topside field‐aligned interhemispheric plasma flows

Substorm auroral onset is often preceded by plasma sheet flow bursts, poleward boundary intensifications (PBIs), and subsequent auroral streamers, suggesting that enhanced transient flows in the plasma sheet propagating toward the near‐Earth plasma sheet play an important role in leading to substorm onset. This study aims at determining the magnetotail source region of preonset PBIs and plasma sheet flows by using the ARTEMIS spacecraft coordinated with the THEMIS all‐sky imager array. ARTEMIS has an advantage of measuring flows between the nominal near‐Earth neutral line (NENL) and distant neutral line (DNL) locations, and thus, the flow direction allows identifying which source region is dominant. We found three preonset conjunction events, and all cases show earthward flow bursts ~10–30 min before substorm onset when PBIs and streamers are detected in the conjugate ionosphere. This time lag is sufficiently long to bring plasma from the ARTEMIS location toward the near‐Earth plasma sheet before onset. The earthward flow direction indicates that preonset enhanced flow channels leading to precursor PBIs originate from further downtail of ARTEMIS, possibly from DNL rather than from NENL. The flow direction changes to tailward after the substorm onset, suggesting that NENL is not related to preonset flow and auroral activity but becomes active during the expansion phase. We determined the source region of pre‐onset PBIs using the ARTEMIS‐ASI pair.All cases show earthward flows ~10‐30 min before substorm onset during PBIs.The earthward flow direction indicates pre‐onset flows originating from DNL.