Abnormal quiet days and the effect of the interplanetary magnetic field on the apparent position of the Sq focus |
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| Authors: | E C Butcher G M Brown |
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| Institution: | Department of Physics, University College of Wales, Aberystwyth, Wales |
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| Abstract: | b
The effect of the IMF on the position of the Sq focus in summer has been discussed by Matsushita who found an apparent poleward motion of the focus on days when the IMF was directed away from the Sun compared to those when the IMF was directed towards the Sun. However, his analysis took no account of the well known phase variability in Sq(H) . It is shown here that if quiet days are separated into 'normal quiet days', NQDs (defined for a station on the poleward side of the focus as days when the minimum in H occurs between 0830 and 1330 LT) and 'abnormal quiet days', AQDs (minimum in H occurring outside the NQD range), then the apparent poleward motion of the focus only occurs on AQDs and even then only when the IMF is directed away from the Sun. This effect is found to occur in both summer and winter and is probably of magnetospheric origin. |
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