Statistical magnetospheric location of auroral omega bands obtained by empirical magnetic field models

Omega bands are curved aurora forms, which appear as rows of inverted Greek letter Ω drifting eastward and may result in substantial magnetic field variations on the ground. Since they were reported for the first time more than 50 years ago, their ionospheric signatures were thoroughly studied to the present moment. In contrast, magnetospheric processes resulting in the omega-bands generation are poorly understood, mostly due to a small number of conjugated spacecraft observations. Therefore, the only possibility to statistically study magnetospheric features of the omega bands is to use different models.

The goal of the present work is to find a characteristic magnetic field configuration corresponding to this type of aurora. We used the list of omega bands (Partamies et al., 2017), observed in the Fennoscandian Lapland in the period 1997-2007, the MIRACLE all-sky camera data, and new empirical magnetic field model (Tsyganenko and Andreeva, 2016) to identify the magnetospheric equatorial location of the observed omega structures. This work presents the most extensive statistical study of the omega bands projections; in previous papers only a case-study mapping based on few events was described. We found that for 90% of the omega bands aurora its possible source is located on the radial distances from the Earth 6-13 Re in the morning sector (2-4 h MLT), with the average position at R=8 Re and 3 MLT. We also estimated a minimal life-time of the omega bands source in the magnetosphere. This study has been funded by the Russian Science Foundation Grant 19-77-10016.

Partamies, N., Weygand, J. M., and Juusola, L.: Statistical study of auroral omega bands, Ann. Geophys., 35, 1069–1083, https://doi.org/10.5194/angeo-35-1069-2017, 2017.
Tsyganenko, N. A., and V. A. Andreeva (2016), An empirical RBF model of the magnetosphere parameterized by interplanetary and ground-based drivers, J. Geophys. Res. Space Physics, 121, doi:10.1002/2016JA023217.