HR: 1330h
AN: SM23A-01    [Abstracts]
TI: Multiple Cusps Observed by Cluster and DMSP Spacecraft
AU: * Zong, Q
EM: zong@bu.edu
AF: Boston University, 725 commonwealth ave., Boston, MA 02215 United States
AB: On March 21- 22, 2001, four cusp-like regions were observed consecutively in about five and half hours by all four Cluster Spacecraft when interplanetary magnetic field (IMF) is northward with a significant By component. The multiple cusps were surrounded by the dayside magnetosphere rather than the magnetopause. Observational evidence showed that the observed multiple cusps were probably a temporal sequence. The boundary normal, velocity and timing analysis for six clear boundaries of the cusps obtained by all four spacecraft indicate that the observed cusps oscillated back and forth. The Cluster spacecraft were oscillating between the dayside magnetosphere and the cusp region. The normal velocities v_n at boundary interfaces (exit from the cusp) are found to be almost three times as larger as that at boundary interfaces (entry into the cusp). There exists clear interfaces between the cusp and the dayside magnetosphere during northward IMF instead of a turbulent entry layer as proposed by Hhaerende. The observations made in this paper suggest the shape and location of the cusp may rarely be static but is often changing as a result of dynamic processes in the high latitude regions.
DE: 2700 MAGNETOSPHERIC PHYSICS
DE: 2720 Energetic particles, trapped
DE: 2724 Magnetopause, cusp, and boundary layers
DE: 2728 Magnetosheath
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: 2005 Joint Assembly