Evidence for weak MHD turbulence in the middle magnetosphere of Jupiter

In this paper we study the small scale-magnetic field fluctuations of the middle Jovian magnetosphere that are embedded in the strong background field B-0 of Jupiter in the framework of turbulence theory. We perform a statistical analysis of these fluctuations using a five year set of Galileo spacecraft magnetic field data. Calculating power spectra of the fluctuations, we identify for the first time a spectral index of minus two for wave vectors perpendicular to B-0. These results strongly support a description of the fluctuations within the framework of weak magnetic turbulence and recent theoretical developments therein by Galtier et al. (2000). In addition, we show that there is little variation of the spectral index upon radial distance in the middle magnetosphere. We comment also on how the presence of such fluctuating fields might have interesting consequences concerning transport properties in the Jovian magnetosphere.