Possible connection of polar cap flows to pre‐ and post‐substorm onset PBIs and streamers

摘要: [1] Recent analysis of a short period observations has led to the hypothesis that enhanced meso-scale flows from well within region open polar cap field lines may cross nightside boundary into closed line and contribute triggering equatorward (earthward) across ionospheric (equatorial) portion plasma sheet fields lead PBIs streamers. This includes streamers have been postulated bring new substorm onset. Meso-scale structure flow cap, often studied near dayside boundary, not previously generally recognized as significant cap. Here we taken advantage capabilities measure convection by Resolute Bay incoherent scatter radar Rankin Inlet PolarDARN radar, coordinated with THEMIS all-sky imager observations, study measurements boundary. We present evidence structures moving toward be important for onset The also given come deep unexpected continuation after in controlling poleward expansion duration post-onset auroral activity.