Evidence on 2-4 day oscillations of the equatorial ionosphere h′F and mesospheric airglow emissions -: art. no. L12102

Equatorial ionospheric sounding has been carried out at Sao Luis (2.6 degrees S,44.2 degrees W). The upper mesosphere-lower thermosphere (MLT) airglow OI5577, O(2)b(0,1) and OH( 6,2) emissions and OH rotational temperature have been observed at Cariri airglow observatory (7.4 degrees S,36.5 degrees W) within a distance of approximately 1000 km to the east of Sao Luis. Both observation sites are located in the equatorial region of South America. Spectral analyses of the ionospheric F-layer bottom height (h'F) and airglow emission intensity reveal that there are quasi 2- and 4-day period oscillations in their temporal variations. This might indicate that planetary scale oscillations, Rossby-gravity waves (or inertial-gravity waves) and Ultra Fast Kelvin waves, are present in the ionosphere. This is the first time that the planetary scale waves in the MLT region and in the ionosphere are discussed by airglow and ionospheric observations, respectively.