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Abstract We present multi‐platform observations of plasma cloak, O+ outflows, kinetic Alfven waves (KAWs), and auroral oval for the geomagnetic storm on 17 March 2015. During the storm's main phase, we observed a generally symmetric equatorward motion of the auroral oval in both hemispheres, corresponding to the plasmasphere erosion and inward motion of the plasma sheet. Consequently, Van Allen Probes became immersed within the plasma sheet for extended hours and repeatedly observed correlated KAWs and O+ outflows. The KAWs contain adequate energy flux toward the ionosphere to energize the observed outflow ions. Adiabatic particle tracing suggests that the O+ outflows are directly from the nightside auroral oval and that the energization is through a quasi‐static potential drop. The O+ outflows from the nightside auroral oval were adequate (‐ #/‐s) and prompt (several minutes) to explain the newly formed plasma cloak, suggesting that they were a dominant initial source of plasma cloak during this storm. 

Abstract Embedded Region 1 and 2 field‐aligned currents (FACs), intense FAC layers of mesoscale latitudinal width near the interface between large‐scale Region 1 and Region 2 FACs, are related to dramatic phenomena in the ionosphere such as discrete arcs, inverted‐V precipitation, and dawnside auroral polarization streams. These relationships suggest that the embedded FACs are potentially important for understanding ionospheric heating and magnetosphere‐ionosphere (M‐I) coupling and instabilities. Previous case studies of embedded FACs have led to the speculation that they may result from enhanced M‐I convection during active times. To explore this idea further, we investigate statistically their occurrence rates under a variety of geomagnetic conditions with a large event list constructed from 17 years of Defense Meteorological Satellite Program observations. The identification procedure is fully automated and explicit. The statistical results indicate that embedded Region 1 and 2 FACs are common, and that they have a higher chance to occur when the level of geomagnetic activity is higher (given by various indices), supporting the idea that they result from enhanced M‐I convection.