Coupling between thermospheric gravity waves and non-migrating tides simulated by the Whole Atmosphere Model

The signatures of gravity waves (GWs) are often observed at ionospheric and thermospheric (IT) heights in satellite and ground-based observations. They play an important role in coupling different regions of the Earth’s atmosphere, as they transport energy and momentum and are often observed during both geomagnetically quiet and active times. GWs at IT heights can either be of meteorological origin propagating up from the lower atmosphere, or generated excited in-situ. They can also non-linearly interact with tides and planetary waves adding to the dynamic variability of the thermosphere. In this study, we aim to investigate the coupling between non-migrating thermospheric tides and GWs during geomagnetically quiet times using the high-resolution whole atmosphere model (WAM) and satellite observations. We find that during daytime, longitudinal signatures of 3, 4, and 5- peak are present in the GW activity, with the 4-peak structure being the predominant one in the lower and upper thermosphere. These signatures are primarily observed at low-latitudes and minimize during December. Our observations from the WAM model signify a modulation of secondary GWs by non-migrating tides, primarily the DE3 tide. We provide the evidence for this modulation and discuss the coupling mechanisms using the Model for Acoustic and Gravity wave Interactions and Coupling (MAGIC). We also show that similar inferences can be made from GOCE and ICON satellite observations within uncertainty.