TY - JOUR

T1 - Omega Band Magnetospheric Source Location: A Statistical Model-Based Study

AU - Andreeva, V. A.

AU - Apatenkov, S. V.

AU - Gordeev, E. I.

AU - Partamies, Noora

AU - Kauristie, Kirsti

N1 - Publisher Copyright: © 2021. American Geophysical Union. All Rights Reserved.

PY - 2021/6

Y1 - 2021/6

N2 - Auroral omega bands have been observed since the 1960s and their ionospheric electrodynamic properties are well established. At the same time magnetospheric source is poorly investigated leaving a room for few competing hypotheses on how the omega band forms. Here we present the statistical study of the projections of about 400 omega bands from the ionosphere to magnetosphere to investigate the location and properties of a possible omega source region in the magnetosphere. We used the Magnetometers—Ionospheric Radars—All-sky Cameras Large Experiment all-sky images on the list of individual omega structures (Partamies et al., 2017, http://doi.org/10.5194/angeo-35-1069-2017) which were observed in the Fennoscandian Lapland in the period of 1997–2007, and a new empirical magnetic field model (Tsyganenko & Andreeva, 2016, https://doi.org/10.1002/2016ja023217) to identify the magnetospheric equatorial projection of the observed omegas. We found that 90% of the auroral omega structures map to the radial distances of 6–14 RE from the Earth, coinciding with the bursty bulk flow braking region. An average magnetic field configuration in the vicinity of magnetospheric omega projections corresponds approximately to the transition region between tail- and dipole-like magnetic configuration. Velocity estimates for omega projections reveal the dawnward as well as the radial propagation in the magnetosphere with a typical speed of up to few tens of km/s. It is shown that the source of omega structures propagates earthward in most of the events.

AB - Auroral omega bands have been observed since the 1960s and their ionospheric electrodynamic properties are well established. At the same time magnetospheric source is poorly investigated leaving a room for few competing hypotheses on how the omega band forms. Here we present the statistical study of the projections of about 400 omega bands from the ionosphere to magnetosphere to investigate the location and properties of a possible omega source region in the magnetosphere. We used the Magnetometers—Ionospheric Radars—All-sky Cameras Large Experiment all-sky images on the list of individual omega structures (Partamies et al., 2017, http://doi.org/10.5194/angeo-35-1069-2017) which were observed in the Fennoscandian Lapland in the period of 1997–2007, and a new empirical magnetic field model (Tsyganenko & Andreeva, 2016, https://doi.org/10.1002/2016ja023217) to identify the magnetospheric equatorial projection of the observed omegas. We found that 90% of the auroral omega structures map to the radial distances of 6–14 RE from the Earth, coinciding with the bursty bulk flow braking region. An average magnetic field configuration in the vicinity of magnetospheric omega projections corresponds approximately to the transition region between tail- and dipole-like magnetic configuration. Velocity estimates for omega projections reveal the dawnward as well as the radial propagation in the magnetosphere with a typical speed of up to few tens of km/s. It is shown that the source of omega structures propagates earthward in most of the events.

KW - ionosphere

KW - magnetosphere

KW - omega bands

KW - aurora

KW - Magnetic field mapping

KW - magnetic field mapping

KW - AURORAL STREAMERS

KW - MORNING-SECTOR

KW - POLEWARD BOUNDARY

KW - PHASE

KW - PRECIPITATION

KW - MAGNETIC-FIELD

KW - SUBSTORMS

KW - ASSOCIATION

KW - PULSATIONS

KW - MAGNETOTAIL

UR - http://www.scopus.com/inward/record.url?scp=85110470417&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/3c7394ce-b021-3bb3-8233-0f39154eab31/

U2 - 10.1029/2020ja028997

DO - 10.1029/2020ja028997

M3 - Article

VL - 126

JO - Journal of Geophysical Research: Space Physics

JF - Journal of Geophysical Research: Space Physics

SN - 2169-9380

IS - 6

M1 - e2020JA028997

ER -