An Investigation of the Influence on Daytime and Evening Vertical ExB Drifts on the Evolution of the Nighttime Equatorial Ionization Anomaly using SAMI3

It has recently been suggested that E region dynamo winds that enhance daytime vertical ExB plasma drifts are the mechanism by which tides generated in the lower atmosphere couple with the F region ionosphere. But it is well known that nighttime ionospheric densities are significantly affected by the pre-reversal enhancement of the ExB drifts, which is primarily driven by the F region dynamo. In this work we investigate the relative contributions of the daytime and evening vertical ExB drifts to the nighttime plasma distributions in the low-latitude F region ionosphere under both solar minimum and maximum conditions. We perform simulation runs using the NRL SAMI3 (Sami3 is Also a Model of the Ionosphere), a three-dimensional physics-based model of the ionosphere, and modulate the vertical velocities of the daytime and prereversal enhancement of the plasma drifts to investigate the effects on the density and separation of the Equatorial Ionization Anomaly (EIA) crests. The role of F region neutral winds is also explored. We discuss our results in light of recent observations of longitudinal variations in the EIA attributed to non-migrating tides generated in the troposphere.