FUV observations of variations in thermospheric composition and topside ionospheric density during the November 2004 magnetic superstorm

Abstract
We revisited the November 2004 superstorm by analyzing TIMED/GUVI data. The 135.6 nm limb radiances at 520-km are mainly due to the O+ and electron radiative recombination and represent the daytime ionosphere density at the altitude. The 135.6 nm radiances clearly showed a signature of ionospheric equatorial arcs and their variations during the November 2004 magnetic superstorm. When an intense eastward Interplanetary Electric Field (IEF) occurred, the dayside equatorial arcs were enhanced and their latitude separation increased. The enhanced equatorial arcs were hemispherically symmetric or asymmetric in the region with non-depleted O/N2 or hemispherically asymmetric O/N2 depletion, respectively. When O/N2 depletion reached the magnetic equator, there was no observable enhancement in the equatorial arcs regardless the IEF conditions, indicating O/N2 condition significantly modulated the variations in storm-time equatorial arcs. GUVI observations also showed that a westward IEF and/or disturbance dynamo electric field could also suppress the dayside equatorial arcs.
Year of Publication
2022
Journal
Journal of Atmospheric and Solar-Terrestrial Physics
Volume
228
Number of Pages
105832
Date Published
feb
ISSN Number
1364-6826
URL
https://www.sciencedirect.com/science/article/pii/S1364682622000086
DOI
10.1016/j.jastp.2022.105832