Study of post sunset vertical plasma drift at equatorial F-region using long-term (1990-2003) ionosonde measurements in Indian longitude

► Post-reversal peak vertical drift of F-layer is weakly depends on solar flux for NDJF. ► Solar flux dependence of Pre- and Post-reversal Vzp is different for two equinoxes. ► PRE is absent in May-August (June-July) during low to moderate (high) solar flux.