Ionospheric response to 2-day planetary wave in the equatorial and low latitude regions

Abstract Planetary scale 2-day waves in the mesosphere–lower thermosphere winds have been observed mainly from January to February in the southern hemisphere low latitude region. Meteor radar wind measurements at Cariri (7.4°S, 36.5°W) from the year 2005 to 2007 showed a distinct 2-day oscillation in the meridional winds with the amplitude of 50–80 m/s and 20–30 m/s for the zonal winds. During the same period, the ionospheric F-layer maximum critical frequency (foF2) observed at Fortaleza (3.8°S, 38.6°W) also showed distinct 2-day oscillation, indicating influence of planetary 2-day wave in the ionosphere. On the other hand, no clear signature of 2-day oscillation was observed for the F-layer bottom-side virtual height (h´F). Present results suggest that the 2-day wave induced meridional wind in the thermosphere could generate latitudinal transport of F-region plasma causing day to day variability of equatorial ionization anomaly (EIA).