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Ann. Geophys., 24, 1367-1374, 2006
www.ann-geophys.net/24/1367/2006/
© European Geosciences Union 2006
Local ionospheric electrodynamics associated with neutral wind fields at low latitudes: Kelvin-Helmholtz billows
J. P. St.-Maurice and R. K. Choudhary
Institute of Space and Atmospheric Studies, University of Saskatchewan, Saskatoon, Canada
Abstract. The Gadanki radar observation of plasma irregularities bearing
the signature of Kelvin-Helmholtz billows above 100 km altitude
raises the question of the electrodynamical mechanism that
would allow the structures to drift with the neutral wind. We
show that for locally varying neutral wind fields with the
right geometry at night, multiple Hall effects in the electron gas
lead to a situation where ions, electrons, and neutrals move
together along the component of the wind that
changes most rapidly in space. The species must not move
together along all directions, however. If this were the case
the plasma would be stable and a radar would be unable to
observe the wind field. We discuss the stability of the
plasma itself for Es layers affected by the Kelvin-Helmholtz wind
field and show that a variety of factors have to be taken into
account beyond the study of the zeroth order mechanism.
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