5:15 PM - 6:45 PM
[PEM13-P12] Spatial development of subauroral polarization stream associated with a pseudobreakup: SuperDARN and Arase observations
Keywords:Earth, Ionosphere, Magnetosphere, Substorm
This study investigates how subauroral polarization streams (SAPS) develop longitudinally and latitudinally in association with a pseudobreakup on the basis of simultaneous conjugate observations made primarily by Super Dual Auroral Radar Network (SuperDARN) in the ionosphere and the Arase and geosynchronous satellites in the inner magnetosphere. In the event of interest during the 2022 Fall SuperDARN-Arase campaign, SuperDARN observed that SAPS appeared and readily intensified at magnetic latitudes of ~67° to ~72° in the evening sector and then expanded azimuthally toward the dusk sector. A close examination shows that SAPS intensified in the dusk sector first at latitudes slightly higher than the ionospheric footprint of Arase situated in the same magnetic local time (MLT) sector, and subsequently the SAPS expanded toward lower latitudes and reached the Arase's footprint. Interestingly, Arase detected drifting clouds of energetic ions at each of the SAPS intensification and the subsequent equatorward expansion, while one of the Geostationary Operational Environmental Satellites (GOES) completely missed any signature of energetic ion injection, despite that the GOES was located at the same MLT but slightly (~0.5 RE) inward of Arase. Considering the simultaneous occurrence of a pseudobreakup seen from ground imager and geomagnetic field data, the observations strongly suggest that intermittent injections of energetic ions occurred at a later MLT and have drifted westward through the Arase location, leading to the observed evolution of SAPS there by supplying downward field-aligned current to the subauroral region. As evident from the GOES observations, the injections did not reach the geosynchronous orbit probably due to a weak electric field associated with the pseudobreakup.