|
|
 |
|
|
Ann. Geophys., 24, 961-972, 2006
www.ann-geophys.net/24/961/2006/
© European Geosciences Union 2006
A numerical model of the ionospheric signatures of time-varying magnetic reconnection: III. Quasi-instantaneous convection responses in the Cowley-Lockwood paradigm
S. K. Morley1,* and M. Lockwood2
1School of Physics and Astronomy, University of Southampton, UK
*also at: CRC for Satellite Systems, University of Newcastle, NSW, Australia
2Rutherford Appleton Laboratory, Chilton, Oxfordshire, UK
Abstract. Using a numerical implementation of the cowlock92 model of
flow excitation in the magnetosphere-ionosphere (MI) system, we
show that both an expanding (on a ~12-min timescale) and a
quasi-instantaneous response in ionospheric convection to the onset
of magnetopause reconnection can be accommodated by the
Cowley-Lockwood conceptual framework. This model has a key feature
of time dependence, necessarily considering the history of the
coupled MI system. We show that a residual flow, driven by prior
magnetopause reconnection, can produce a quasi-instantaneous global
ionospheric convection response; perturbations from an equilibrium
state may also be present from tail reconnection, which will
superpose constructively to give a similar effect. On the other
hand, when the MI system is relatively free of pre-existing flow, we
can most clearly see the expanding nature of the response. As the
open-closed field line boundary will frequently be in motion from
such prior reconnection (both at the dayside magnetopause and in the
cross-tail current sheet), it is expected that there will usually be
some level of combined response to dayside reconnection.
Full Article in PDF (3118 KB) |
|
|
