by M.S. Dhadly (Space Science Division, Naval Research Laboratory), J.T. Emmert (Space Science Division, Naval Research Laboratory), M. Jones (), E.N. Doornbos (KNMI), K.A. Zawdie ()D.P. Drob (Space Science Division, Naval Research Laboratory)M. Conde (Geophysical Institute, University of Alaska Fairbanks)
This study explores intra‐annual oscillations (IAOs) in upper thermospheric winds using GOCE cross‐track wind measurements between 70°S and 70°N. Due to the Sun‐synchronous dawn‐dusk orbit of GOCE, the cross‐contamination between seasonality and local time variations in winds is minimal, which makes it a unique space‐based data set to extract IAOs and study their latitudinal variation. Our analysis reveals that the annual (AO), semiannual (SAO), and terannual (TAO) oscillations are robust features in thermospheric winds. The AO is strongest at middle latitudes; SAO and TAO amplitudes increase with increasing latitude. The latitudinally averaged amplitudes of the AO, SAO, and TAO for dusk/dawn are 30.0/35.0, 8.5/11.3, and 6.0/6.6 m/s, respectively. The phase of AO reverses around the equator. SAO and TAO phases vary with latitude but do not reverse like the AO. For both the SAO and TAO, the average phase at dusk and dawn differs by ∼30 days.
Dhadly, M.S., J.T. Emmert, M. Jones, E.N. Doornbos, K.A. Zawdie, D.P. Drob and M. Conde, Oscillations in Neutral Winds Observed by GOCE