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

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 degrees S, 36.5 degrees 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 degrees S, 38.6 degrees 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 (hF). 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). (C) 2012 Elsevier Ltd. All rights reserved.