Auroral Morphological Changes to the Formation of Auroral Spiral during the Late Substorm Recovery Phase: Polar UVI and Ground All-Sky Camera Observations ...

• Main Authors: Nowada, Motoharu, Miyashita, Yukinaga, Partamies, Noora, Degeling, Alexander William, Shi, Quan-Qi
• Format: Text
• Language: unknown
• Published: arXiv 2022
• Subjects: Space Physics physics.space-ph; Plasma Physics physics.plasm-ph; FOS Physical sciences; Longyearbyen; Svalbard
• Online Access: https://dx.doi.org/10.48550/arxiv.2205.00244; https://arxiv.org/abs/2205.00244

The ultraviolet imager (UVI) of the Polar spacecraft and an all-sky camera at Longyearbyen contemporaneously detected an auroral vortex structure (so-called "auroral spiral") on 10 January 1997. From space, the auroral spiral was observed as a "small spot" (one of an azimuthally-aligned chain of similar spots) in the poleward region of the main auroral oval from 18 h to 24 h magnetic local time. These auroral spots were formed while the substorm-associated auroral bulge was subsiding and several poleward-elongated auroral streak-like structures appeared during the late substorm recovery phase. During the spiral interval, the geomagnetically north-south and east-west components of the geomagnetic field, which were observed at several ground magnetic stations around Svalbard island, showed significant negative and positive bays caused by the field-aligned currents related with the aurora spiral appearance. The negative bays were reflected in the variations of local geomagnetic activity index (SML) which was ... : 40 Pages, 6 Figures (8 pages), 1 Table, and Supporting Information file (including 2 Figures (8 pages) and 1 Movie) ...