MAL11

A long-standing question within Saturn’s magnetosphere is the source of the ubiquitous oscillations, known as planetary period oscillations (PPOs). From radio and magnetometer data it is known there are two such oscillation systems, one in the northern hemisphere and the other in the southern. In this talk, we will review analyses of azimuthal magnetic field data from the Cassini mission right up to its end in 2017 which show the presence of field-aligned currents. Using these data, several field-aligned current systems are shown to be present in Saturn’s auroral regions and their relationship with the PPOs was revealed. The implications of these results on Saturn’s periodicities, aurora, and coupling between the ionosphere and magnetosphere will be discussed.  

How to cite: Hunt, G.: Saturn's field-aligned current systems as observed by the Cassini mission, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13335, https://doi.org/10.5194/egusphere-egu22-13335, 2022.

I will review the main magnetosphere-ionosphere (MI) coupling mechanisms thought to play a role at Jupiter and at Saturn. We are interested in the extent to which the magnetospheres are driven by internal processes (plasma sources, planetary rotation) versus external mechanisms (solar wind, interplanetary magnetic field). At both planets, momentum is mostly transferred via the rotating planetary magnetic field from the ionosphere to the magnetosphere. The solar wind can also play a role in driving dynamics, e.g. via the interaction of corotating interaction regions (CIRs). The NASA/ESA Cassini Huygens mission revealed that Saturn’s system also has a unique feature driven by the ionosphere known as “planetary period oscillations”. These phenomena interact with the effects of the solar wind to produce complex MI coupling signatures. The NASA Juno mission has provided the first in situ evidence of MI coupling in Jupiter's polar magnetosphere. I will compare the similarities and differences between observation and theory discovered thus far.

How to cite: Bunce, E.: Magnetosphere-Ionosphere Coupling and Aurora at Jupiter and Saturn, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11375, https://doi.org/10.5194/egusphere-egu22-11375, 2022.