Observations of Non-Migrating Diurnal Tides in Middle Thermosphere Temperature and Composition with GOLD

Abstract:

Non-migrating diurnal tides impose both large periodic longitudinal variations and net perturbations on the thermosphere, especially at low-latitudes and solar minimum. The spectrum of non-migrating diurnal tides in the mesosphere/lower thermosphere and upper thermosphere is now well-characterized as a result of many observations taken by spacecraft in low Earth orbit. It is thought that non-migrating diurnal tides are present in the middle thermosphere where they perturb the atmospheric temperature, but they have yet to be characterized due to a lack of global-scale systematic observations of temperatures at these altitudes. Since October 2018, the GOLD Mission has been imaging O/N₂ column density ratios and middle thermosphere temperatures. As GOLD only measures temperatures and O/N₂ ratios during daylight, and over the ~140° of longitude visible from its position in geostationary orbit, previously developed tidal analysis techniques do not apply to the GOLD dataset. Here we present a novel approach that deduces dominant, non-migrating diurnal tides in simultaneous measurements of temperature and composition made by GOLD. We discuss application of the method to both simulated GOLD data and actual GOLD data products.