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Ann. Geophys., 23, 385-391, 2005
www.ann-geophys.net/23/385/2005/
© European Geosciences Union 2005
Morning quiet-time ionospheric current reversal at mid to high latitudes
R. Stening1, T. Reztsova1, D. Ivers2, J. Turner2, and D. Winch2
1School of Physics, University of New South Wales, Sydney NSW 2052 Australia
2School of Mathematics and Statistics, University of Sydney, Sydney 2006, Australia
Abstract. The records of an array of magnetometers set up across the Australian
mainland are examined. In addition to a well-defined current whorl
corresponding to the ionospheric Sq current system, another system of
eastward flowing currents is often found in the early morning. The system is
most easily identified at observatories poleward of the focus of the Sq
system, where a morning reversal from eastward to westward currents can be
seen. The time of the reversal is usually later, sometimes up to 12h local
noon, in June (Southern Winter) than in other seasons. There is some
evidence of a similar current system at other longitudes and in the Northern Hemisphere.
An important outcome of the study is that it enables
identification of which features of a daily variation of the northward
magnetic field ΔX relate to an Sq current whorl and which must be
attributed to some other current system.
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