Wednesday

The accumulated observational information on Saturn planetary period oscillations (PPOs) from the Cassini orbital phase places limits on the stress, forces and torques exerted by the signals on the magnetospheric plasma. Hitherto unnoticed is that the field aligned current latitudinal distributions suggest that the PPOs can be the primary means for angular momentum transfer between ionosphere and magnetosphere on closed field lines, i.e. more important than the traditional steady current system associated with sub-corotation. This would imply PPO phenomena are thus a fundamental dynamic feature of the ionised ionosphere-magnetosphere coupling system in the Saturn system rather than a by-product of a process in the neutral atmosphere. In addition, the signal phase structure indicates magnetospheric currents have a strong resistive component which would mean that the heavy ion plasma diffusing outward from Enceladus and ring sources is absorbing the energy and angular momentum transmitted from the ionosphere in the PPO fields. This carries implications for the time scale of the transverse plasma diffusion process but also can one speculate also that the PPOs also play a part in the actual diffusion process of the heavy material?