Image of IMAGE in space

Plasmasphere Lags Behind Earth Rotation


For decades, space physicists have assumed that the thin outer layers of our atmosphere, called the plasmasphere, rotate with the Earth, as Earth's magnetic field pulls these charged particles along. IMAGE-EUV imaging has shown that the inner plasmasphere when no space weather 'storms' are in progress, actually rotates at a rate that is 10% slower than Earth so that the particles require about 27-hours to complete a full trip around the Earth. Comparisons with the DMSP satellite's ion drift data for the same events show that this '10%' corotation lag also exists in the ionosphere where it is caused by a process called the "ionospheric disturbance dynamo" [see Burch et al., 2004]. This result by IMAGE has far-reaching implications for scientists who are attempting to understand, and construct models of an important process called magnetospheric convection. Until this surprising result, scientists have always assumed strict corotation of the plasmasphere.

(2003: Sandel et al.)

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Additional Information

Plasmasphere -An extension of Earth's upper atmosphere and ionosphere into space. This material is a charged plasma with particle energies below 100 electron Volts. The plasma is anchored to Earth's magnetic field and is dragged into a 24-hour 'co-rotational' orbit out to 10,000 kilometers or more.

Magnetospheric convection - The transport of plasma and energy within the magnetosphere in a manner similar to the way in which water boils in a pot, causing turbulence.

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Dr. S. Odenwald,, +1-301-286-6953
NSSDC, Mail Code 630, NASA Goddard Space Flight Center, Greenbelt, MD 20771
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Rev. 1.0.0, 24 July 2004, EVB II