[1] Subauroral ion drifts (SAID) are the prominent feature of the active subauroral geospace, just earthward of the electron plasma sheet (PS) boundary in the premidnight sector. We explore magnetically conjugate satellite observations of substorm SAID near the magnetic equator and in the topside ionosphere confirming and expanding on our previous results. The SAID channels reside between the hot electron (PS/auroral) boundary at the plasmapause and the drop in the hot ion flux inside the plasmasphere. The overall features are inconsistent with the paradigm of voltage and current generators. Rather, they are explained in terms of a short circuiting of substorm-injected hot plasma jets over the plasmapause and formation of a turbulent plasmaspheric boundary layer. The short circuiting occurs when the cold plasma density exceeds a critical value of 5-10 cm -3 . As the polarization field at the front of the hot plasma jet is shorted out, the hot electrons are arrested, while the hot ions yet move inward. This provides a natural explanation of the long-known dispersionless auroral precipitation boundary. Enhanced plasma turbulence within the SAID channel provides anomalous circuit resistivity and magnetic diffusion, as with the well-documented plasmoid-magnetic barrier problem.

[1] We report on oscillations in electric (dE Y ) and magnetic (dB Z ) fields and plasma density (dN i ) observed by Defense Meteorological Satellite Program (DMSP) satellites within fast subauroral convection streams in the evening sector during the magnetic storm of 6 November 2001. There are two types of wave phenomena. The first and more common is characterized by electromagnetic and plasma density variations that have the same frequency range of $0.15 Hz in the spacecraft frame of reference. The second is characterized by large-amplitude plasma and field oscillations over a broader range of frequencies $0.1 to 0.3 Hz. In this case the perturbation densities and fields appear to have different frequency responses. In this and other magnetic storms, strong waves are associated with the precipitation of $30 keV ions. Ratios of dE Y /dB Z indicate encounters with mixtures of electromagnetic (in part Alfvénic) and electrostatic modes. Poynting vectors associated with the oscillations can be directed either into or out of the ionosphere. The density perturbations appear to be extended east-west corrugations in the plasma flow streams with north-south wavelengths of $50 km. The dE Y and dN i variations were anticorrelated, as required for current conservation. Our analysis shows that Alfvénic perturbations are consistent with expected effects of irregular potential distribution around ionospheric density irregularities mapped to the magnetosphere. Inertial currents act to generate mesoscale field-aligned currents carried by Alfvén waves, as was previously discussed with regards to auroral arcs formation. We suggest that dN i irregularities observed by DMSP satellites in the evening sector began as striated plasma patches in the polar cap that convected to subauroral latitudes.

We present multispacecraft observations of enhanced flow/electric field channels in the inner magnetosphere and conjugate subauroral ionosphere, i.e., subauroral polarization streams (SAPS) near dusk and subauroral ion drifts (SAID) near midnight. The channels collocate with ring current (RC) injections lagging the onset of substorms by a few to ∼20 min, i.e., significantly shorter than the gradient‐curvature drift time of tens of keV ions. The time lag is of the order of the propagation time of reconnection‐injected hot plasma jets to the premidnight plasmasphere and the substorm current wedge (SCW) to dusk. The observations confirm and expand on the previous results on the SAID features that negate the paradigm of voltage and current generators. Fast‐time duskside SAPS/RC injections appear intimately related to a two‐loop circuit of the substorm current wedge (SCW2L). We suggest that the poleward electric field inherent in the SCW2L circuit, which demands closure of the Region 1 and Region 2 sense field‐aligned currents via meridional currents, is the ultimate cause of fast RC injections and SAPS on the duskside.

We present three STEVE (strong thermal emission velocity enhancement) events in conjunction with Time History of Events and Macroscale Interactions (THEMIS) in the magnetosphere and Defense Meteorological Satellite Program (DMSP) and Swarm in the ionosphere, for determining equatorial and interhemispheric signatures of the STEVE purple/mauve arc and picket fence. Both types of STEVE emissions are associated with subauroral ion drifts (SAID), electron heating, and plasma waves. The magnetosphere observations show structured electrons and flows and waves (likely kinetic Alfven, magnetosonic, or lower‐hybrid waves) just outside the plasmasphere. Interestingly, the event with the picket fence had a >~1 keV electron structure detached from the electron plasma sheet, upward field‐aligned currents (FACs), and ultraviolet emissions in the conjugate hemisphere, while the event with only the mauve arc did not have precipitation or ultraviolet emission. We suggest that the electron precipitation drives the picket fence, and heating drives the mauve as thermal emission.

[1] We compare plasma and field disturbances observed in the ring current/plasmasphere overlap region and in the conjugate ionosphere during the magnetic storm of 5 June 1991. Data come from the Combined Release and Radiation Effects Satellite (CRRES) flying in a geostationary transfer orbit and three satellites of the Defense Meteorological Satellite Program (DMSP) series in Sun-synchronous polar orbits. In the region between ring current nose structures and the electron plasma sheet, CRRES detected wave-like features in local electric and magnetic fields, embedded in structured cold plasmas. Mapped to the ionosphere, these fields should reflect structuring within subauroral plasma streams (SAPS). Indeed, during the period of interest, DMSP F8, F9, and F10 satellites observed highly structured SAPS in the evening ionosphere at topside altitudes. They were collocated with precipitating ring current ions, enhanced fluxes of suprathermal electrons and ions, elevated electron temperatures, and irregular plasma density troughs. Overall, these events are similar to electromagnetic structures observed by DMSP satellites within SAPS during recent geomagnetic storms (Mishin et al., , 2004. Their features can be explained in terms of Alfvén and fast magnetosonic perturbations. We developed a scenario for the formation of elevated electron temperatures at the equatorward side of the SAPS. It includes a lower-hybrid drift instability driven by diamagnetic currents, consistent with strong lower-and upper-hybrid plasma wave activity and intense fluxes of the low-energy electrons and ions near the ring current's inner edge.Citation: Mishin, E. V., and W. J. Burke (2005), Stormtime coupling of the ring current, plasmasphere, and topside ionosphere: Electromagnetic and plasma disturbances,