“…Satellite traces in equatorial ionograms appear as one or more quasi replicas of the Flayer trace at displaced virtual heights prior to the ESF onset, and are probably produced by oblique reflections from upwelling walls, that is, corrugations in the isodensity surfaces. This issue was very well illustrated by Tsunoda (2008) who provided further evidence, besides those advanced by Wright (1959), Lyon (1961), Abdu et al (1981), andMcNamara et al (2008), that STs are a characteristic precursor of ESF over the equatorial belt. Fagundes et al (2009a, b), as well, showed that PSSR can be strongly modulated by traveling planetary wave ionospheric disturbance oscillations.…”