Variations in the Density Distribution of the Io Plasma Torus as Seen by Radio Occultations on Juno Perijoves 3, 6, and 8

The atmosphere of the Jovian satellite Io is constantly being lost to the surrounding magnetosphere of Jupiter. The material is ionized and then distributed by Jupiter's magnetic field into a torus around Jupiter called the Io plasma torus. This plasma affects radio signals as they propagate from the Juno spacecraft to Earth during the spacecraft's perijove passes. During Perijoves 3, 6, and 8 we determine the total electron content in the Io plasma torus using two-way tracking data from Juno. We find that the location of the torus is displaced from predictions that use the VIP4 offset tilted dipole approximation. The displacements are consistent with those found in ground-based observations. The peak total electron content and scale height are found for two different regions of the torus, the cold inner torus and a warmer torus beyond 5.5 R_J. Properties of the cold torus vary appreciably with System III longitude, but properties of the torus beyond 5.5 R_J do not.