Day-to-day variability in equatorial spread F: Is there some physics missing?

[1] Attempts continue to be made, without notable success, to identify the source of day-to-day variability in occurrence of equatorial spread F (ESF). Most seek to uncover a controlling factor in one of the parameters that describe the linear growth rate of the Rayleigh-Taylor (RT) instability. It is possible, however, that some physics is still missing in that description of ESF generation. Consideration is given here to an F-region response to a large-scale polarization electric field that is generated by a sporadic-E layer instability (Cosgrove and Tsunoda, 2002) and mapped to the bottomside of the F(2) layer. Results indicate that the large-scale wave structure, the most reliable precursor for ESF, may be initiated by this process at the base of the F(2) layer, where plasma drift is westward.