Quasi-two-day wave-tide interactions as revealed in satellite observations

In this paper we demonstrate how observations from Sun-synchronous and quasi-Sun-synchronous satellites can be analyzed to reveal the signatures of nonlinear interactions between tides and planetary waves in Earth's mesosphere and lower thermosphere. This is done by ordering data in longitude space, and demonstrating how peaks in the spectra of such data series can be identified with specific waves or combinations of waves. We use as an example the quasi-two-day wave (QTDW) oscillations in temperature observed by the Microwave Limb Sounder (MLS) instrument on the Aura satellite and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on the TIMED satellite. We show that the QTDW not only produces secondary waves due to nonlinear interactions with the migrating (Sun-synchronous) diurnal and semidiurnal tides, but that secondary waves are also produced by nonmigrating tide-QTDW interactions. Moreover, these latter secondary waves are of similar amplitude to the resident tides and the QTDW, and serve an important role in defining longitude structures due to the presence of these waves.