|
|
 |
|
|
Ann. Geophys., 23, 2095-2105, 2005
www.ann-geophys.net/23/2095/2005/
© European Geosciences Union 2005
E-region wind-driven electrical coupling of patchy sporadic-E and spread-F at midlatitude
S. Shalimov1 and C. Haldoupis2
1Institute of the Physics of the Earth, Moscow, Russia
2Physics Department, University of Crete, Iraklion, Greece
Abstract. This paper investigates the role of neutral winds
in the generation of relatively large polarization electric fields
across patchy sporadic-E layers, which then map upward to the
F region, to create conditions for medium-scale spread-F. The
calculations are based on an analytical model that uses the
current continuity equation and field-aligned current closures to
the F region in order to describe quantitatively a Hall
polarization process inside sporadic-E plasma patches during
nighttime. In applying this model we use experimentally known
values for E and F region, conductances, the ambient electric
fields and prevailing neutral winds, in order to estimate the
polarization fields that build up inside sporadic-E. It is found
that the relatively strong west-southwest neutral winds during
summer nighttime can provide the free energy for the
generation of sizable polarization electric fields, which have
comparable eastward and north-upward components and reach values
of several mV/m. Given that the sporadic-E patches have sizes
from a few to several tens of kilometers, the polarization fields
can map easily to the F region bottomside where they impact
ExB plasma uplifts and westward bulk
motions, in line with key observational properties of medium-scale
spread-F. However, the present simple model needs further
development to also include wind forcing of the F region plasma
and possible polarization processes inside spread-F.
Keywords. Ionosphere (Electric fields and currents; Ionospheric
irregularities; Mid-latitude ionosphere)
Full Article in PDF (348 KB) |
|
|
