Detection of high-latitude magnetic reconnection between the northward interplanetary magnetic field and a closed magnetic field wedge linked to a transpolar arc

Abstract

Transpolar arcs (TPAs) describe a subset of auroral emissions observed poleward of the Earth's main auroral ovals when the interplanetary magnetic field (IMF) is northward. These emissions are thought to align with a “wedge” of closed magnetic field lines extending to the high-latitude boundary of the Earth's magnetosphere, where they are postulated to interact with the IMF through magnetic reconnection. Such an instance of “high-latitude TPA wedge reconnection” is expected to open the Earth's magnetic field lines, but the event has never been verified by in situ observations. Here we report a detection of a high-latitude TPA wedge reconnection site within one ion gyroradius distance on 18 March 2002, which manifests in the ionosphere as colocation of the TPA and a cusp spot. The result may explain previously reported cases of remotely detected “non-lobe” high-latitude magnetic reconnection, with implications for future understanding of TPAs and northward-IMF global magnetospheric dynamics.

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Identifiers

ORCID for Nawapat Kaweeyanun: orcid.org/0000-0003-0634-0164

ORCID for Robert C. Fear: orcid.org/0000-0003-0589-7147

ORCID for Daniel K. Whiter: orcid.org/0000-0001-7130-232X

ORCID for Imogen L. Gingell: orcid.org/0000-0003-2218-1909

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