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Ann. Geophys., 22, 73-91, 2004
www.ann-geophys.net/22/73/2004/
© European Geosciences Union 2004
A numerical model of the ionospheric signatures of time-varying magneticreconnection: I. ionospheric convection
M. Lockwood1,2 and S. K. Morley2
1Rutherford Appleton Laboratory, Chilton, Oxfordshire, UK
2Department of Physics and Astronomy, University of Southampton, Southampton, Hampshire, UK
Abstract. This paper presents a numerical model for predicting the evolution of the
pattern of ionospheric convection in response to general time-dependent magnetic
reconnection at the dayside magnetopause and in the cross-tail current sheet of the
geomagnetic tail. The model quantifies the concepts of ionospheric flow excitation
by Cowley and Lockwood (1992), assuming a uniform spatial distribution of
ionospheric conductivity. The model is demonstrated using an example in which
travelling reconnection pulses commence near noon and then move across the dayside
magnetopause towards both dawn and dusk. Two such pulses, 8min apart, are used
and each causes the reconnection to be active for 1min at every MLT that they pass
over. This example demonstrates how the convection response to a given change in
the interplanetary magnetic field (via the reconnection rate) depends on the previous
reconnection history. The causes of this effect are explained. The inherent
assumptions and the potential applications of the model are discussed.
Key words. Ionosphere (ionosphere-magnetosphere interactions;
plasma convection) – Magnetospheric physics (magnetosphere-ionosphere interactions;
solar wind-magnetosphere interactions)
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