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Ann. Geophys., 20, 1837-1842, 2002
www.ann-geophys.net/20/1837/2002/
© European Geosciences Union 2002
Night-time F-region and daytime E-region ionospheric drifts measured at Udaipur during solar flares
B. M. Vyas and R. Pandey
Department of Physics, M. L. Sukhadia University, Udaipur 313 001, India
Correspondence to: R. Pandey (pandey r@yahoo.com)
Abstract. Ionospheric drifts
measured at a low latitude station, Udaipur (Geomag. Lat. 14.5° N), in the
night-time F-region and daytime E-region during solar flares have been studied.
The night-time observations, which correspond to the F-region drifts, were
carried out on five different nights. The daytime observation corresponding to
the E-region drifts is only for one day. It is found that the apparent drift
during the solar flare period is reduced considerably, in the daytime E-region
as well as in the night-time F-region. The East-West and North-South components
of the apparent drift speed are also similarly affected. For the daytime
E-region drifts during a flare, increased ionization and subsequent reduction
of reflection height is proposed to be the cause of reduced drift speeds. For
the night-time F-region drifts, a reduced electric field at the F-region
heights resulting from coupling of sunlit and dark hemispheres has been
proposed to be the possible cause.
Key words. Ionosphere (electric fields and currents;
ionospheric disturbances)
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