Plasma wave characteristics of the Jovian magnetopause boundary layer: Relationship to the Jovian aurora?
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California (United States)
- Centre dEtude des Environnements Terrestre et Planetaires/Universite Versailles-Saint-Quentin, Velizy (France)
- Institute d`Astrophysique Spatiale, University of Paris XI, Orsay (France)
- University of Minnesota, School of Physics and Astronomy, Minneapolis, Minnesota (United States)
- Los Alamos National Laboratory, Los Alamos, New Mexico (United States)
- Blackette Laboratory, Imperial College of Science and Technology, London (England)
- Max-Planck-Institut fuer Aeronomie, Katlenburg-Lindau (Germany)
- Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland (United States)
The Jovian magnetopause boundary layer (BL) plasma wave spectra from 10{sup {minus}3} to 10{sup 2}Hz have been measured for the first time. For one intense event the magnetic (B{prime}) and electric (E{prime}) spectra were 2{times}10{sup {minus}4}f{sup {minus}2.4}nT{sup 2}/Hz and 4{times}10{sup {minus}9}f{sup {minus}2.4}V{sup 2}/m{sup 2}Hz, respectively. Although no measurable wave amplitudes were detected above the electron gyrofrequency, {approximately}140Hz, this finding may be due to the low signal strength characteristic of this region. The B{prime}/E{prime} ratio is relatively frequency independent. It is possible that waves are obliquely propagating whistler mode waves. The B{prime} and E{prime} spectra are broadband with no obvious spectral peaks. The waves are sufficiently intense to cause cross-field diffusion of magnetosheath plasma to create the BL itself. A BL thickness of 10,700 km is predicted, consistent with past in situ measurements. The Jovian boundary layer wave properties are quite similar to the BL waves at Earth (however, the Jovian waves are orders of magnitude less intense). It appears that the solar wind/magnetosphere dynamos at the two planets are similar enough to be consistent with a common wave generation mechanism. The predicted ionospheric latitudinal width of the BL of {approximately}100{endash}200km is quite similar to the Jovian auroral high-latitude ring. The location of the BL at and inside the foot point of the last closed field line may place the boundary layer and the aurora on approximately the same magnetic field lines. The Jovian BL waves are sufficiently intense to cause strong pitch angle diffusion for {lt}5-keV electrons and 1-keV to 1-MeV protons. The estimated energy precipitation rate from this interaction {lt}1ergcm{sup {minus}2}s{sup {minus}1}, sufficient for a weak high-latitude auroral ring. This intensity is 2 to 3 orders of magnitude too low to cause the main aurora ring, however. (Abstract Truncated)
- OSTI ID:
- 548811
- Journal Information:
- Journal of Geophysical Research, Vol. 102, Issue A3; Other Information: PBD: Mar 1997
- Country of Publication:
- United States
- Language:
- English
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