The Jovian Magnetosphere And Magnetopause

It is convenient to divide the magnetosphere into three regions. The inner magnetosphere extends from the surface to about 25 R_J and is dominated by the basically dipolar field. The outer magnetosphere, on the sunward side, occupies a layer roughly 15 R_J thick just inside the magnetopause. Here the field direction was found by Pioneers 10 and 11 to have a strong southward component, 5 to 10 times as strong as expected if one scales the observations in the Earth's magnetosphere. The middle magnetosphere is the remaining region. Its thickness, again on the sunward side, varies greatly as the magnetopause moves in and out. In this region the field direction turns as one goes outward from nearly dipolar to nearly radial but with a persistent southward component. The field is outward in the northern hemisphere, inward in the southern, separated by a thin (~1 or 2 R_J) warped current sheet in which the magnetic field appears to be very weak and mainly southward.