HR: 1340h
AN: SM13B-0340    [Abstracts]
TI: Radial and Local Time Variations in the Thickness of the Jovian Current Sheet
AU: * Schwarzl, H K
EM: schwarzl@igpp.ucla.edu
AF: Institute of Geophysics and Planetary Physics, Slichter Hall, UCLA, Los Angeles, CA 90095 United States
AU: Khurana, K K
EM: kkhurana@igpp.ucla.edu
AF: Institute of Geophysics and Planetary Physics, Slichter Hall, UCLA, Los Angeles, CA 90095 United States
AB: We have developed a new and highly automated technique for determining the thickness of Jupiter's current sheet from magnetic field data over all local times and radial distances. The technique determines current sheet thickness by fitting a Harris neutral sheet description to the observations. The four parameters required for the fits are the lobe field strength B_L, the current sheet thickness D, a local vertical shift of the current sheet Δ z, and a local azimuthal shift of the current sheet Δ φ. In regions where the spacecraft does not emerge from the current sheet, a lower limit of the thickness is assigned which is equal to the maximum excursion of the spacecraft from the center of a model current sheet. In this study we use data from all of the spacecraft that have explored the current sheet of Jupiter. In general the current sheet thickens with increasing radial distance from Jupiter for all local times. Within a radial distance of 20 R_J, the half-thickness of the current sheet is 1.5 to 2.5 R_J. The current sheet thickness is largest on the dusk side and continuously increases with radial distance. In addition, a strong increase in thickness starts at 40 R_J at dusk with the current sheet half-thickness exceeding 15 R_J. On the dawn side we see a local thinning of the current sheet (with half thickness approaching 1 R_J) at a radial distance of 30 R_J. This thin current sheet region is part of a wedge shaped region that starts at local midnight and can still be observed up to 0800 local time. Beyond 30 R_J even at dawn, the current sheet thickens up to a half- thickness of 5 R_J at a radial distance of 80 R_J. At local midnight the maximum observed half-thickness is ~ 8 R_J at a radial distance of 140 R_J. Finally, on the dayside the current sheet thickness exceeds 6 R_J at a radial distance of 50 R_J in a high B_z region called the cushion region. We will explore ideas which explain some of the variability of the current sheet thickness in Jupiter's magnetosphere.
DE: 2740 Magnetospheric configuration and dynamics
DE: 2764 Plasma sheet
DE: 5443 Magnetospheres (2756)
DE: 5737 Magnetospheres (2756)
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005