Does high-latitude “nonlobe” reconnection under northward IMF involve closed magnetic field lines linked to polar cap auroras?

High-latitude reconnection between the northward IMF and the Earth’s magnetosphere typically involves open lobe magnetic field lines in the polar cap. However, a study of cusp plasma populations reported unusual high-latitude reconnection events featuring closed “nonlobe” magnetic field lines, whose presence at the magnetopause was not explained (Fuselier et al., 2018). Partial/Complete closure of the polar cap has been linked to mechanisms with telltale transpolar auroral arc (TPA) and horse-collar aurora (HCA) signatures, but can these mechanisms explain the observed nonlobe reconnection? We analyse auroral signatures during 12 nonlobe reconnection events identified by Fuselier et al., (2018). Of these, 9 events (75%) exhibit evidence for a TPA or an HCA within two hours of the reconnection time, a rate far exceeding expectation from random sampling (~20%). The result suggests strongly that nonlobe reconnection can be explained by either TPA wedge reconnection (Kaweeyanun et al., 2025) or dual lobe reconnection that produces HCAs (Milan et al., 2020b). If so, cusp plasma observations can be used to detect both types of reconnection, greatly expanding the size of available event samples that will allow further investigations into the phenomena, including calculation of the reconnection rate.