In the magnetosphere, there are several major current systems controlled by the interaction of the Earth’s field with the solar wind. The strength of the total magnetospheric field is closely tied to solar and solar wind variations and to plasma outflow from the ionosphere. The major magnetospheric magnetic fields are a result of: magnetopause currents; cross-tail currents, and the symmetric and partial ring currents.
Magnetopause currents flow to shield the internal field from the IMF. And connect to a cross-tail current sheet that separates lobes of opposite magnetic polarity, extending hundreds of Earth radii down-wind from the Earth. An azimuthal drift of plasma (westward for ions, eastwards for electrons) around the Earth produces the symmetric ring current. The partial, or asymmetric, ring current is found on the dusk-side of the Earth and is closed via ionospheric currents. 0 provides the general morphology of model magnetospheric field lines, according to the Tsyganenko 1989 model [RD.111] showing the seasonal variation, dependent on rotation axis tilt. This figure shows a cut in the noon-midnight plane.