The global context of the 14 November 2012 storm event

Abstract

AbstractFrom 2 to 5 UT on 14 November 2012, the Van Allen Probes observed repeated particle flux dropouts during the main phase of a geomagnetic storm as the satellites traversed the post‐midnight to dawnside inner magnetosphere. Each flux dropout corresponded to an abrupt change in the magnetic topology, i.e., from a more dipolar configuration to a configuration with magnetic field lines stretched in the dawn‐dusk direction. Geosynchronous GOES spacecraft located in the dusk and near‐midnight sectors and the LANL constellation with wide local time coverage also observed repeated flux dropouts and stretched field lines with similar occurrence patterns to those of the Van Allen Probe events. THEMIS recorded multiple transient abrupt expansions of the evening‐side magnetopause ∼20–30 min prior to the sequential Van Allen Probes observations. Ground‐based magnetograms and all sky images demonstrate repeatable features in conjunction with the dropouts. We combine the various in situ and ground‐based measurements to define and understand the global spatiotemporal features associated with the dropouts observed by the Van Allen Probes. We discuss various proposed hypotheses for the mechanism that plausibly caused this storm‐time dropout event as well as formulate a new hypothesis that explains the combined in situ and ground‐based observations: the earthward motion of magnetic flux ropes containing lobe plasmas that form along an extended magnetotail reconnection line in the near‐Earth plasma sheet.