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Ann. Geophys., 23, 1755-1761, 2005
www.ann-geophys.net/23/1755/2005/
© European Geosciences Union 2005
Polar cap influx
J. MacDougall and P. T. Jayachandran
Dept. Electrical Engineering, University of Western Ontario, London, Ont., N6A 5B9, Canada
Abstract. This study uses digital ionosonde data from a cusp
latitude station (Cambridge Bay, 77° CGM lat.) to study the convection
into the polar cap. Days when the IMF magnetic field was relatively steady
were used. On many days it was possible to distinguish an interval near noon
MLT when the ionosonde data had a different character from that at earlier
and later times. Based on our data, and other published measurements, we
used the interval 10:00-13:00 MLT as the cusp interval and calculated the
convection into the polar cap in this interval. The integrated convection
accounted for only ~1/3 of the open polar cap flux. If the convection
through the prenoon/postnoon regions on either side of the cusp was
calculated the remaining 2/3 of the flux could be accounted for. The
characteristics of the prenoon/postnoon regions were different from the cusp
region, and we attribute this to transient flank merging versus more steady
frontside merging for the cusp.
Keywords. Ionosphere (Plasma convection) Magnetospheric
physics (Polar cap phenomenon)
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