The reaction of our magnetosphere to the arrival of solar wind depends on the wind's particle composition and speed, as well as the direction of its accompanying magnetic fields. An interaction of a solar wind field toward (T) and away (A) from the Sun (see Section 3.5.4, p. 94) with the downstream magnetospheric tail boundary causes a change in the 24-hr component phase (Figure 3.20) of the vertical field component at the polar regions. Using a chain of observatories, it was possible to establish the equivalent polar ionospheric current system behavior (Figure 5.9) in the polar regions at low activity times. The researchers have found that the appearance time of the major polar current vortex shifts regularly with the toward and away sectors.
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