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Abstract
We document the activation of transient polar arcs emanating from the cusp within a 15 min long intermediate phase during the transition from a standard two-cell convection pattern, representative of a strongly southward interplanetary magnetic field (IMF), to a "reverse" two-cell pattern, representative of strongly northward IMF conditions. During the 2–3 min lifetime of the arc, its base in the cusp, appearing as a bright spot, moved eastward toward noon by ~ 300 km. As the arc moved, it left in its "wake" enhanced cusp precipitation. The polar arc is a tracer of the activation of a lobe convection cell with clockwise vorticity, intruding into the previously established large-scale distorted two-cell pattern, due to an episode of localized lobe reconnection. The lobe cell gives rise to strong flow shear (converging electric field) and an associated sheet of outflowing field-aligned current, which is manifested by the polar arc. The enhanced cusp precipitation represents, in our view, the ionospheric footprint of the lobe reconnection process.
Publication Date
5-31-2001
Journal Title
Annales Geophysicae
Publisher
EGU
Digital Object Identifier (DOI)
Document Type
Article
Recommended Citation
Sandholt, PE; Farrugia, CJ; Cowley, SWH; Lester, M; Cerisier, JC (2001). Excitation of transient lobe cell convection and auroral arc at the cusp poleward boundary during a transition of the interplanetary magnetic field from south to north, ANNALES GEOPHYSICAE. Vol. 19, No. 5, 487-493. DOI: 10.5194/angeo-19-487-2001
Comments
This is an article published by EGU in Annales Geophysicae in 2001, available online: https://dx.doi.org/10.5194/angeo-19-487-2001