15:30 〜 15:45
[PEM12-37] Ionospheric response to the competition between penetration electric field and thermospheric O/N2
★Invited Papers
キーワード：Thermosphere composition (O/N2 ratio), Topside ionosphere, Penetration electric field, Thermospheric FUV emission, geomagentic storm, interplanetary electric field
We revisited the November 2004 superstorm by analyzing TIMED/GUVI data which provide information of both thermosphere and ionosphere. When an intense eastward Interplanetary
Electric Field (IEF) or Penetration Electric Field (PEF) 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 or PEF conditions, indicating O/N2 condition significantly modulated the variations in storm-time equatorial arcs. GUVI observations also showed that a westward IEF (PEF) and/or disturbance dynamo electric field could also suppress the dayside equatorial arcs.
Electric Field (IEF) or Penetration Electric Field (PEF) 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 or PEF conditions, indicating O/N2 condition significantly modulated the variations in storm-time equatorial arcs. GUVI observations also showed that a westward IEF (PEF) and/or disturbance dynamo electric field could also suppress the dayside equatorial arcs.