HR: 1330h
AN: SA23A-01    [Abstracts]
TI: Changes in EUV created conductivity as a result of geomagnetic storms
AU: * Burns, A
EM: aburns@ucar.edu
AF: High Altitude Observatory National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 United States
AU: Wang, W
EM: wbwang@ucar.edu
AF: High Altitude Observatory National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 United States
AU: Killeen, T
EM: killeen@ucar.edu
AF: High Altitude Observatory National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 United States
AU: Solomon, S
EM: stans@ucar.edu
AF: High Altitude Observatory National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 United States
AU: Wiltberger, M
EM: wiltbemj@ucar.edu
AF: High Altitude Observatory National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 United States
AB: Although much of the current flowing between the magnetosphere and the ionosphere is conducted horizontally through ionization produced by auroral precipitation, a significant amount may be conducted through ionization produced by solar UV and EUV ionization. The latter effect should be more important in the summer hemisphere where solar UV and EUV radiation can produce ionization across the polar cap. However, the importance of this solar EUV induced ionization depends on its not being changed significantly by the effects of auroral precipitation. In this talk, we use the Coupled Magnetosphere-Ionosphere-Thermosphere model to show that the conductivity associated with solar UV and EUV radiation is in fact considerably reduced during geomagnetic storms to the point where the changes produced in the system are of the same order of magnitude as the seasonal differences. Furthermore, we show that the causes of these changes occurs both as a result of a change in ion density near 120 km, and as a result of changes in ion composition from the collisionally effective O2+ to the less collisionally effective NO+. Both this change in composition and the reduction in ion densities are the result of the build up of NO during the geomagnetic storm.
DE: 0355 Thermosphere--composition and chemistry
DE: 2435 Ionospheric disturbances
DE: 2437 Ionospheric dynamics
SC: SPA-Aeronomy [SA]
MN: 2005 Joint Assembly