The equations are modeled in a frame co-rotating with Jupiter’s magnetosphere. In this frame, Io moves westward at a speed of 57 km/s, leading to an emf of VIoB 0 of 120 mV/m. This effect is included in the second term in the equation forE ν in equation . Io is modeled as a cloud of conductivity which is constant over the diameter of Io and falls off as the distance squared in Io’s ionosphere. As noted above, the simulation is based on magnetic coordinates, so that Io moves in a plane inclined about 10° from the magnetic equator. Similarly, the mass density in the Io plasma torus is centered on the centrifugal equator. We use two density profiles: a “high-density” case based on the density model of Dougherty et al. (2017), and a “low-density” case based on the model considered by Ray et al. (2009). These densities are taken to be independent of longitude along the centrifugal equator. The density and the resulting Alfvén speed cA are plotted in Figure 1, with Figures 1a and 1b giving the density for the low- and high-density cases, respectively, while Figures 1c and 1d show the corresponding Alfvén speed profiles. The high-density case results in a density of 200 cm−3 at a radial distance of 2 RJ, while the low-density case has 0.1 cm−3 at this altitude. The trajectory of Io in magnetic coordinates is plotted as a solid line in these figures. These models have a total Alfvén transit time from one ionosphere to the other of 16 minutes in the high-density case and 12 minutes in the low-density case. These values are comparable to the one-way transit times between 12.5 and 15 minutes in the model of Hinton et al. (2019).