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Ann. Geophys., 20, 639-645, 2002
www.ann-geophys.net/20/639/2002/
© European Geosciences Union 2002
Noon ionospheric signatures of a sudden commencement following a solar wind pressure pulse
A. Vontrat-Reberac1, J.-C. Cerisier2, N. Sato3, and M. Lester
1CETP/CNRS, Paris, France
2National Institute of Polar Research, Tokyo, Japan
3University of Leicester, UK
Correspondence to: J.-C. Cerisier
(jean-claude.cerisier@cetp.ipsl.fr)
Abstract. Using experimental data
from the Cutlass Super-DARN HF radars and from a subset of ground magnetometers
of the IMAGE Scandinavian chain, the response of the ionosphere in the noon
sector to a solar wind pressure increase is studied. The emphasis is on the
signature of the convection vortices and of the Hall currents that are
associated with the pair of opposite parallel currents flowing along the
morning and afternoon high-latitude magnetic field lines. We show that the
sudden commencement is characterised by an equatorward convection, immediately
followed (within less than 3 min) by a strong poleward plasma motion. These
results are shown to agree qualitatively with the global model of sudden
commencement of Araki (1994).
Key words. Ionosphere (plasma
convection; electric fields and currents) – Magnetospheric physics (solar
wind-magnetosphere interactions)
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