Atmospheric Tides and Their Effects on Ionosphere-Thermosphere-Mesosphere (ITM) Dynamics, Composition, and Structure

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This project aims to better delineate the global manifestations of non-migrating tides from the stratosphere through the thermosphere and to better determine the origin of the non-migrating tides which is largely in the troposphere. The investigation of the non-migrating tidal signatures will include examination of their intra-annual, intra-seasonal, and inter-annual variations. Observational data will be employed to drive non-migrating tidal solutions in the Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (GCM) and the Thermosphere-Ionosphere-Electrodynamics GCM housed at the National Center for Atmospheric Research (NCAR). These will be used to obtain realistic simulations of global atmospheric tidal perturbations in winds, temperatures, densities, minor constituents, airglow emissions, electric fields, and ionospheric composition from 30 km to 500 km altitude. Temperature measurements from the TIMED spacecraft between plus-and-minus 50 degrees latitude and 20 - 120 km altitude during 2002-2008, combined with tidal theory, will provide the temperature, wind, and geopotential perturbations needed by the models in order to parameterize and represent tidal effects at the models' lower boundaries. Latest determinations of radiative and latent heating due to rainfall will be included as well as the specification of planetary waves. The model results will form a framework for the interpretation of existing measurements of tidal variations over the globe, especially in terms of the longitude variability in the mesosphere-thermosphere-ionosphere region which recent observations from ground and space have shown to be significant. This longitude variability is pervasive and occurs in neutral winds and temperatures, minor constituent densities and airglow emissions, and ionospheric parameters such as plasma density and electric fields. In terms of broader impacts, the project will support a Ph.D. student and include undergraduate students in the research activities. Since the study will help in the understanding and interpretation of diverse satellite data sets, it will be a resource for satellite science programs in both analysis and interpretation of results, and help improve the NCAR upper atmosphere models.