HR: 0800h
AN: GP31A-0065    [Abstracts]
TI: Time-dependent mapping of storm-time magnetospheric ring-current structure
AU: * Love, J J
EM: jlove@usgs.gov
AF: USGS Geomagnetism Program, Box 25046 MS 966 DFC, Denver, CO 80225 United States
AU: Green, J C
EM: Janet.Green@noaa.gov
AF: NOAA Space Environment Center, 325 Broadway, Boulder, CO 80305 United States
AB: Magnetometer data from approximately 40 mid-latitude ground-based magnetic observatories are used to study the time-dependent structure of the magnetospheric ring current during two large storms in October and November of 2003. After making adjustments for observatory latitude and subtracting quite-time variation, an equivalent equatorial ring current that varies in intensity as a function of longitude is derived by fitting the magnetometer data to a truncated Fourier series. Storm-time variations of the ring current are derived with a continuous temporal series of such fittings. Final results are displayed as a movie, which illuminates the dynamic, time-dependent evolution of the ring current over the duration of each storm. Significant longitudinal asymmetry is seen during the main phases of both storms, with more symmetry seen during the recovery phases On the other hand, the two storms show pronounced differences in ring-current structure during their initial onsets. Comparisons are made with the traditional ring-current measures of Dst and Asym; preliminary comparisons are also made with space-based data and the magnetic-field signatures of field-aligned currents.
UR: http://geomag.usgs.gov
DE: 1530 Rapid time variations
DE: 2721 Field-aligned currents and current systems (2409)
DE: 2756 Planetary magnetospheres (5443, 5737, 6033)
DE: 2778 Ring current
DE: 2788 Magnetic storms and substorms (7954)
SC: Geomagnetism and Paleomagnetism [GP]
MN: Fall Meeting 2005