It is well-established that electric fields of magnetospheric origin can penetrate to mid- and low-latitudes during magnetically active periods [Kelley et al., 1979; Spiro et al., 1988; Fejer and Scherliess, 1995; Basu et al., 2001; Huang et al., 2005] and that these fields can substantially modify low- to mid-latitude ionospheric plasma properties.