Seasonal and Annual Variations in Winds and Temperature Terdiurnal Tides in the Ionosphere seen with ICON, MIGHTI and SD-WACCMX

The Earth’s upper atmosphere is highly dynamic and plays an important role in coupling processes between the lower atmosphere and the near-space environment. Atmospheric tides, which originate in the lower atmosphere and propagate upward, are a major source of variability in the thermosphere and ionosphere. These global-scale waves can influence ion production, loss, and transport processes, making their characterization important for understanding vertical coupling within the atmosphere–ionosphere system.
This study investigates the variability of atmospheric tides using observations from the Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) instrument aboard the ICON satellite. The dataset spans 2019–2022 and provides global measurements of neutral winds and temperatures across altitudes from approximately 90–300 km and latitudes between 6°S and 42°N during both day and night local times. Tidal components are extracted by fitting the observations to a wave model, enabling reconstruction of individual tidal modes and examination of their temporal and spatial variability across latitude, altitude, and time.
To provide additional context for the observations, the derived tidal structures are compared with simulations from the Specified Dynamics Whole Atmosphere Community Climate Model with thermosphere–ionosphere extension (SD-WACCM-X). Consistent temporal averaging and correlation analyses are applied to both datasets to investigate similarities and differences in tidal variability. This comparison helps assess the model’s ability to reproduce observed tidal signatures and provides insight into the role of atmospheric tides in coupling processes between the middle and upper atmosphere.