Impact of Nonmigrating Tides on the Thermospheric Energy Budget and Constituents

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This project aims to delineate and understand the impact of non-migrating tides on parameters important to the aeronomy of the ionosphere-thermosphere system, such as constituents, infrared emission rates and the thermospheric energy budget. Non-migrating tides are pervasive and known to occur in neutral winds, temperature, neutral density, and ionospheric parameters such as plasma densities and electric fields. They manifest themselves in longitude and local time variability, which recent observations from ground and space have shown to be significant. Based on these new findings, significant non-migrating tidal variations may also be present in thermospheric composition and in the infrared emission of energy to the lower atmosphere and to space. This variability will affect the ionosphere-thermosphere system in various ways, including its photochemistry, energy budget, and neutral-plasma coupling. The investigation will examine the tidal variability in [O]/[N2] column density ratio and in nitric oxide and carbon dioxide volume emission rates of energy, connect it quantitatively with the tides in temperature and winds and provide an assessment of the relative importance for neutral-plasma coupling and the thermospheric energy budget as function of season and solar cycle. Towards this goal, the project will synergistically employ data from the GUVI and SABER instruments on the TIMED satellite and an existing, observation-based model of temperature and wind tides in the thermosphere. GUVI will provide the [O]/[N2] column density and SABER nitric oxide and carbon dioxide volume emission rates of energy emitted at 5.3 microns and 15 microns, respectively. The project will support a Ph.D. student and involve summer undergraduate students in the research. Non-migrating tides largely originate in the troposphere as heat is released by evaporation and condensation near the surface. The effects to be investigated are thus a measure for the geospace response to tropospheric weather and how energy and momentum are transported from the lower into the upper atmosphere. The study will provide observational constraints for an important neutral-plasma coupling process, tidal [O]/[N2] variations, that is predicted by current mechanistic and first principles models. It will provide first insight into the weather impact on Earth's "natural thermostat", the nitric oxide 5.3 micron emissions, by which heat and solar energy are efficiently lost from the thermosphere to space and to the lower atmosphere.