HR: 1330h
AN: SM32B-1149    [PDF]
TI: Sawtooth Oscillations Directly Driven by Solar Wind Dynamic Pressure Enhancements
AU: * Lee, D
EM: dylee@ast.chungbuk.ac.kr
AF: Chungbuk National University, Dept. of Astronomy and Space Science,, Cheongju, 361-763 Korea, Republic of
AU: Lyons, L
EM: larry@atmos.ucla.edu
AF: UCLA, Department of Atmospheric Sciences 405 Hilgard Ave., Los Angeles, 90095-1565 United States
AB: We have examined four well-defined events of sawtooth oscillations in energetic particle flux and magnetic field at geosynchronous orbit. During all four events, nearly simultaneous energetic particle flux enhancements and magnetic field variations occurred at all MLTs for each sawtooth cycle. Geomagnetic H component data at low-to-mid latitude also show a global H-increase simultaneously with the geosynchronous responses at all MLTs. These global simultaneous occurrences are what is expected from a response of the magnetosphere to solar wind dynamic pressure enhancements. By directly checking the solar wind data, we indeed find that there exist a series of solar wind dynamic pressure enhancements for each sawtooth event. We show that each cycle of the sawtooth oscillation can be associated in timing with a corresponding solar wind dynamic pressure enhancement. Furthermore, details of solar wind variations are sometimes well seen in the corresponding responses in geosynchronous particle flux, geosynchronous magnetic field, and geomagnetic H-component on the ground. Variations in the orientations, structure, and propagation speed of solar wind discontinuities prevent a one-to-one correspondence with each sawtooth oscillation from being determined with precise temporal accuracy. However, the global H-component increases as well as northern and southern PC index enhancements indicate that the solar wind pressure enhancements did indeed impact the magnetosphere at appropriate times. Therefore we suggest that the sawtooth oscillations studied in this paper are directly driven by series of solar wind pressure enhancements, and are not successively occurring substorms.
DE: 2720 Energetic particles, trapped
DE: 2730 Magnetosphere--inner
DE: 2784 Solar wind/magnetosphere interactions
DE: 2788 Storms and substorms
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting