Plasma wave characteristics of the Jovian magnetopause boundary layer: Relationship to the Jovian aurora?

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Read Full Article Cited by JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 102, NO. A3, PAGES 4751–4764, 1997 Plasma wave characteristics of the Jovian magnetopause boundary layer: Relationship to the Jovian aurora? Bruce T. Tsurutani Jet Propulsion Laboratory, California Institute of Technology, Pasadena John K. Arballo Jet Propulsion Laboratory, California Institute of Technology, Pasadena Bruce E. Goldstein Jet Propulsion Laboratory, California Institute of Technology, Pasadena Christian M. Ho Jet Propulsion Laboratory, California Institute of Technology, Pasadena Gurbax S. Lakhina Jet Propulsion Laboratory, California Institute of Technology, Pasadena Edward J. Smith Jet Propulsion Laboratory, California Institute of Technology, Pasadena Nicole Cornilleau-Wehrlin Centre d'Etude des Environnements Terrestre et Planétaires/Université Versailles-Saint-Quentin, Vélizy, France Renée Prangé Institute d'Astrophysique Spatiale, University of Paris XI, Orsay, France Naiguo Lin University of Minnesota, School of Physics and Astronomy, Minneapolis Paul Kellogg University of Minnesota, School of Physics and Astronomy, Minneapolis John L. Phillips Los Alamos National Laboratory, Los Alamos, New Mexico Andre Balogh Blackette Laboratory, Imperial College of Science and Technology, London, England Norbert Krupp Max-Planck-Institut für Aeronomie, Katlenburg-Lindan, Germany Mark Kane Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland Abstract The Jovian magnetopause boundary layer (BL) plasma wave spectra from 10⁻³ to 10² Hz have been measured for the first time. For one intense event the magnetic (B′) and electric (E′) spectra were 2 × 10⁻⁴ ƒ^2.4 nT²/Hz and 4 × 10⁻⁹ ƒ^2.4 V²/m² Hz, respectively. Although no measurable wave amplitudes were detected above the electron gyrofrequency, ∼140 Hz, this finding may be due to the low signal strength characteristic of this region. The B′/E′ ratio is relatively frequency independent. It is possible that waves are obliquely propagating whistler mode waves. The B′ and E′ 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 Jovian BL thickness of 10,700 km is predicted, which is 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 ∼100–200 km is quite similar to the Jovian auroral high-latitude ring measured by Hubble. 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 <5-keV electrons and 1-keV to 1-MeV protons. The estimated energy precipitation rate from this interaction <1 erg cm⁻² s⁻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. If it is found that this main aurora maps into the boundary layer, then other mechanisms such as (ionospheric) double layers must be responsible for the particle energization and precipitation. Received 3 May 1996; accepted 6 September 1996. Read Full Article Cited by Citation: Tsurutani, B. T., et al. (1997), Plasma wave characteristics of the Jovian magnetopause boundary layer: Relationship to the Jovian aurora?, J. Geophys. Res., 102(A3), 4751–4764. Copyright 1997 by the American Geophysical Union.

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