Physics
Scientific paper
Dec 2002
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002agufmsm11d..04w&link_type=abstract
American Geophysical Union, Fall Meeting 2002, abstract #SM11D-04
Physics
2116 Energetic Particles, Planetary, 2740 Magnetospheric Configuration And Dynamics, 2756 Planetary Magnetospheres (5443, 5737, 6030), 2764 Plasma Sheet
Scientific paper
The Energetic Particles Detector (EPD) onboard Galileo has been measuring the three-dimensional intensity distributions of energetic ions and electrons throughout the Jovian magnetosphere from 10 RJ to beyond 140 RJ into the distant magnetotail. Spherical harmonic analysis of the distributions yields 8 of the 9 coefficients for the zeroth, first, and second order harmonics, and by estimating the final missing coefficient, parameters describing the streaming properties of the energetic particles may be derived. Specifically, plasma flow velocities are measured independently for three ion species (H, O, and S) at energies 20-100 keV/nucl, and spectral indices and partial pressures of both ions and electrons are obtained. These parameters are used to investigate both the local structure of the Jovian plasma sheet, which the spacecraft encounters once or twice every planetary rotation period, as well as variations throughout the Jovian magnetosphere on a global scale. Plasma sheet crossings are characterized by a systematic reversal of the magnetic field direction and enhancement in energetic particle intensities. Although the spatial structure of the plasma sheet cannot be determined directly by a single spacecraft, the organization of the measured streaming parameters with respect to the local magnetic field configuration, particularly the radial component, may be used as a reliable proxy for its local structure and motion. Local sheet structure is investigated for 85 individual encounters with the plasma sheet in the inner and middle Jovian magnetosphere. Well ordered variations of the observed streaming parameters across the plasma sheet are a persistent, yet sometimes puzzling, feature of the observations, which often show a dependence on local time and radial distance from the planet. For example, the center of the plasma sheet at small radial distances is commonly characterized by a significant hardening of the ion and electron spectra, while at larger radial distances, the spectra soften at the center of the sheet. Also, the edges of the sheet feature sharp changes in the azimuthal velocity, indicative of velocity shear at the plasma sheet boundary. In addition to studying the local plasma sheet structure, the measured parameters are used to investigate variations on a global scale. Evidence for a dependence on local time and/or radial distance from the planet is observed for several energetic particle parameters, including spectral index, partial pressure, and the direction of the plasma flow. Although the plasma sheet characteristics are remarkably consistent from one crossing to the next, the observations are not consistent with any simple model of Jovian plasma sheet structure and motion of which we are aware.
Fritz Teresa A.
Galland Kivelson Margaret
Roelof Edmond C.
Waldrop Lara Suzon
No associations
LandOfFree
Local and Global Jovian Plasma Sheet Characteristics Observed by the Galileo Energetic Particles Detector does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Local and Global Jovian Plasma Sheet Characteristics Observed by the Galileo Energetic Particles Detector, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Local and Global Jovian Plasma Sheet Characteristics Observed by the Galileo Energetic Particles Detector will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1438202