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Ann. Geophys., 20, 1193-1201, 2002
www.ann-geophys.net/20/1193/2002/
© European Geosciences Union 2002
A model of mid-latitude E-region plasma convergence inside a planetary wave cyclonic vortex
S. Shalimov1 and C. Haldoupis
Physics Department, University of Crete, Iraklion, Crete, 710 03, Greece
1permanently at the Institute of Physics of the Earth, Moscow, Russia
Correspondence to: C. Haldoupis (chald@physics.uoc.gr)
Abstract. Recently, Shalimov et al.
(1999) proposed a new mechanism for large-scale accumulation of long-lived
metallic ions in the mid-latitude ionosphere driven by planetary waves in the
lower thermosphere. In this mechanism, the combined action of frictional and
horizontal magnetic field forces at E-region altitudes causes the plasma to
converge and accumulate in large areas of positive neutral wind vorticity
within a propagating planetary wave. The present paper provides a theoretical
formulation for this mechanism by modelling both horizontal and vertical plasma
transport effects within a planetary wave vortex, of cyclonic neutral wind.
Non-steady-state numerical solutions of the ion continuity equation show that
the proposed accumulation process can enhance the ionization significantly
inside the planetary wave vortex but its efficiency depends strongly on
altitude, whereas on the other hand, it can be complicated by vertical plasma
motions. The latter, which are driven by the same planetary wave wind field
under the action of the vertical Lorentz force and meridional wind forcing
along the magnetic field lines, can lead to either plasma compressions or
depletions, depending on the prevailing wind direction. We conclude that, for
shorter times, vertical plasma transport may act constructively to the
horizontal gathering process to produce considerable E-region plasma
accumulation over large sectors of a planetary wave vortex of cyclonic winds.
Key words. Ionosphere
(ionosphere-atmosphere interactions; mid-latitude ionosphere; sporadic
E-layers) – Meteorology and atmospheric dynamics (waves and tides)
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