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Ann. Geophys., 23, 2501-2510, 2005
www.ann-geophys.net/23/2501/2005/
© European Geosciences Union 2005
A numerical model of the ionospheric signatures of time-varying magnetic reconnection: II. Measuring expansions in the ionospheric flow response
S. K. Morley1,* and M. Lockwood1,2
1School of Physics and Astronomy, University of Southampton, UK
2Rutherford Appleton Laboratory, Chilton, Oxfordshire, UK
*now at: CRC for Satellite Systems, University of Newcastle, NSW, Australia
Abstract. A numerical model embodying the concepts of the Cowley-Lockwood
(Cowley and Lockwood, 1992, 1997) paradigm has been used to produce
a simple Cowley-Lockwood type expanding flow pattern and to
calculate the resulting change in ion temperature.
Cross-correlation, fixed threshold analysis and threshold relative
to peak are used to determine the phase speed of the change in
convection pattern, in response to a change in applied reconnection.
Each of these methods fails to fully recover the expansion of the
onset of the convection response that is inherent in the
simulations. The results of this study indicate that any expansion
of the convection pattern will be best observed in time-series data
using a threshold which is a fixed fraction of the peak response. We
show that these methods used to determine the expansion velocity can
be used to discriminate between the two main models for the
convection response to a change in reconnection.
Keywords. Magnetospheric physics (Magnetosphereionosphere
interactions) – Ionosphere (Plasma convection;
Modeling and forecasting)
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