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The Spring 2011 issue of The Earth Scientist is focused on modernizing seismology education. Thanks to IRIS, you can download this issue for free as a pdf. Print copies are available in our online store.

Charged Particle Motion in Earth's Magnetosphere

High-latitude Ionosphere

The magnetosphere not only supplies energetic particles that cause the aurora, but it also drives strong winds and electric currents in the high-latitude ionosphere and thermosphere.

Animation courtesy the COMET and HAO programs at UCAR/NCAR.

The magnetospheric convection that carries plasma and magnetic field from the dayside magnetopause into the magnetotail and back again also stirs winds in the high latitude ionosphere and thermosphere. These winds circulate from the dayside auroral ovals across the polar caps to the night side, then around the dawn and dusk sides back to the dayside.

Animation courtesy the COMET and HAO programs at UCAR/NCAR.

In the lower part of the ionosphere, from about 80 to 150 kilometers, the electric field associated with the magnetosphere-ionosphere circulation drives strong horizontal electric currents.

Electrical currents in the E-region of the ionosphere

Because of the peculiar nature of ionospheric conductivity, there are actually two high-latitude current systems. One system comprises Hall currents, which flow perpendicular to both the electric and magnetic fields and are strongest near 105 kilometers altitude. The other system is made up of Pedersen currents, which flow perpendicular to the magnetic field and parallel to the electric field and are strongest near 125 kilometers altitude. These two ionospheric current systems connect via field-aligned currents to the magnetospheric current system.

Hall, Pedersen, and Field-aligned currents in the polar ionosphere

Last modified May 17, 2005 by Randy Russell.

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