Auroral omega bands: Solar wind drivers and role in storm and substorm processes

Omega bands are mesoscale auroral structures that appear as eastward-moving poleward protrusions of the auroral oval. Typically, omega bands are observed in the post-midnight sector during geomagnetically active periods, and are associated with pairs of upward- and downward-aligned field aligned currents connecting to the magnetotail outside the geostationary distance. The magnetospheric or solar wind drivers of these dynamic structures are not well understood.

Recent analysis of 28 omega band events identified with THEMIS ASI between 2006 and 2013 shows that omega bands are associated with compression regions in the solar wind (Cribb et al., 2024). Analysis of 200 omega band events identified with the MIRACLE network between 1996 and 2007 yields similar results, highlighting the role of high solar wind density in driving the auroral activity. Here we complement the solar wind observations with GOES measurements from geostationary orbit and ground magnetic observations from the SuperMAG database to identify magnetosphere-ionosphere coupling processes that occur during these intervals. Our results will shed light on how solar wind-magnetosphere-ionosphere coupling processes operate during medium to strong geomagnetic storms.