HR: 08:00h
AN: SA21B-01    [Abstracts]
TI: Observations and simulations of the ionospheric and thermospheric response to the December 2006 geomagnetic storm: Initial phase
AU: * Lei, J
EM: leijh@ucar.edu
AF: High Altitude Observatory, National Center for Atmospheric Research, 3080 Center Greeen, Boulder, CO 80303, United States
AU: Wang, W
EM: wbwang@ucar.edu
AF: High Altitude Observatory, National Center for Atmospheric Research, 3080 Center Greeen, Boulder, CO 80303, United States
AU: Burns, A G
EM: aburns@ucar.edu
AF: High Altitude Observatory, National Center for Atmospheric Research, 3080 Center Greeen, Boulder, CO 80303, United States
AU: Solomon, S C
EM: stans@ucar.edu
AF: High Altitude Observatory, National Center for Atmospheric Research, 3080 Center Greeen, Boulder, CO 80303, United States
AU: Richmond, A D
EM: richmond@hao.ucar.edu
AF: High Altitude Observatory, National Center for Atmospheric Research, 3080 Center Greeen, Boulder, CO 80303, United States
AU: Wiltberger, M
EM: wiltbemj@ucar.edu
AF: High Altitude Observatory, National Center for Atmospheric Research, 3080 Center Greeen, Boulder, CO 80303, United States
AU: Goncharenko, L P
EM: lpg@haystack.mit.edu
AF: Haystack Observatory, Massachusetts Institute of Technology, Route 40, Westford, MA 01886, United States
AU: Coster, A
AF: Haystack Observatory, Massachusetts Institute of Technology, Route 40, Westford, MA 01886, United States
AU: Reinisch, B W
EM: Bodo_Reinisch@uml.edu
AF: Center for Atmospheric Research, University of Massachusetts, 600 Suffolk Street, Lowell, MA 01854, United States
AB: We have investigated the thermospheric and ionospheric response to the 14-15 December, 2006 geomagnetic storm using a Coupled Magnetosphere Ionosphere Thermosphere (CMIT) 2.0 model simulation. Here we focus on observations and simulations during the initial phase of the storm (about 8 hours), when the shock was driving changes in geospace. The global ionospheric maps of total electron content (TEC), ionosonde data at four stations and Millstone Hill incoherent scatter radar (ISR) observations are compared with the corresponding simulation results from the CMIT model. The observations showed significant positive storm effects occurred in the Atlantic sector after the onset of this storm. The CMIT model is able to capture the temporal and spatial variations of the ionospheric storm effects seen in the GPS TEC observations, although the model slightly underestimates the daytime positive ionospheric storm in the South American sector. The simulations are also in agreement with the ionosonde and ISR ionospheric measurements. Term analysis of the ion continuity equation demonstrates that changes in the electric fields play a dominant role in generating the observed ionospheric positive storm effect in the American sector during the initial phase, although neutral winds and composition changes also contribute. The difference in the strength of the enhancements over North and South America can be explained by the slope of the topside electron density profiles in the two hemispheres. Nighttime changes in electron density in other longitude sectors are also small, because the topside electron densities also decrease slowly with altitude at night.
DE: 2435 Ionospheric disturbances
DE: 2437 Ionospheric dynamics
DE: 2736 Magnetosphere/ionosphere interactions (2431)
SC: SPA-Aeronomy [SA]
MN: 2007 Fall Meeting