HR: 11:15h
AN: SM42A-04    [Abstracts]
TI: Characterizing the April 18, 2002 Storm-time Sawtooth Events using Ground Magnetic Data
AU: * Clauer, C R
EM: rclauer@umich.edu
AF: University of Michigan, Center for Space Environment Modeling, 2455 Hayward, Ann Arbor, MI 48109-2143
AU: Cai, X
EM: xcai@umich.edu
AF: University of Michigan, Center for Space Environment Modeling, 2455 Hayward, Ann Arbor, MI 48109-2143
AU: Welling, D
EM: dwelling@umich.edu
AF: University of Michigan, Center for Space Environment Modeling, 2455 Hayward, Ann Arbor, MI 48109-2143
AU: DeJong, A
EM: dejonga@umich.edu
AF: University of Michigan, Center for Space Environment Modeling, 2455 Hayward, Ann Arbor, MI 48109-2143
AU: Henderson, M G
AF: Los Alamos National Laboratory, MSD466, Los Alamos, NM 87545
AB: Global periodic sawtooth oscillations begin during the main phase and dominate for over 12 hours the magnetic storm activity on April 18, 2002. We examine the individual sawtooth events and determine that their characteristics are consistent with large, periodic sutstorm disturbances, however, these disturbances are different from typical isolated substorms in a few important ways. First, they are global. The extent of the substorm current wedge, measured using the midlatitude local time magnetic disturbance profile, is approximately 8 hours of local time, compared with 4 hours for typical isolated substorms. The injection region observed in energetic particle flux data at geostationary orbit extends across the entire tail and past the dawn and dusk terminators into the dayside in contrast to the more typical injection region that is limited to a few hours of MLT in the tail. In addition, they appear to be quasi-periodic, however they are driven by a steady solar wind driver. Thus, they do not conform to the "loading - unloading" substorm paradigm. Such driving conditions have been thought to produce Steady Magnetospheric Convection events, however, it appears that they may also produce sawtooth oscillations. It remains to be determined what parameters/conditions control the development of SMC or sawtooth oscillations during periods of steady magnetospheric driving, such as the magnetic cloud that is driving the April 18, 2002 activity reported here.
DE: 2708 Current systems (2409)
DE: 2740 Magnetospheric configuration and dynamics
DE: 2776 Polar cap phenomena
DE: 2778 Ring current
DE: 2788 Storms and substorms
SC: SPA-Magnetospheric Physics [SM]
MN: 2005 Joint Assembly