GMDD Geoscientific Model Development Discussions GMDD Geosci. Model Dev. Discuss. 1991-962X Göttingen, Germany 10.5194/gmd-2019-339 Interaction of Small-Scale Gravity Waves with the Terdiurnal Solar Tide in the Mesosphere and Lower Thermosphere Lilienthal Friederike 1 Yiğit Erdal https://orcid.org/0000-0002-2819-2521 2 Samtleben Nadja 1 Jacobi Christoph https://orcid.org/0000-0002-7878-0110 1 Institute for Meteorology, Universität Leipzig, Stephanstr. 3, 04103 Leipzig, Germany Department of Physics and Astronomy, Space Weather Lab, George Mason University, Fairfax, VA, USA Deutsche Forschungsgemeinschaft JA836/30-1 JA836/32-1 JA836/38-1 03 02 2020 2020 1 23 Copyright: © 2020 Friederike Lilienthal et al. 2020 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://gmd.copernicus.org/preprints/gmd-2019-339/ The full text article is available as a PDF file from https://gmd.copernicus.org/preprints/gmd-2019-339/gmd-2019-339.pdf

Implementing a nonlinear whole atmosphere gravity wave (GW) parameterization into the Middle and Upper Atmosphere Model extending to the lower thermosphere (160 km), we study the response of the atmosphere in terms of the circulation patterns, temperature distribution, and migrating terdiurnal solar tide activity to the upward propagating small-scale internal GWs originating in the lower atmosphere. We perform three test simulations for the Northern Hemisphere winter conditions in order to assess the effects of variations in the initial GW spectrum on the dynamics of the mesosphere and lower thermosphere. We find that the overall strength of the source level momentum flux has a comparatively small impact on zonal mean dynamics. The tails of the GW source level spectrum, however, are crucial for the lower thermosphere dynamics. With respect to the terdiurnal tide, we find a strong dependence of tidal amplitude on the induced GW drag, generally being larger when GW drag is increased.