This repository contains changes to Multi-Scale Gravity Wave Model (MS-GWaM) code and the atmospheric model ICON (version 2.6.5-nwp1b with upper atmosphere extension) necessary to implement the Gravity Wave - Turbulence Coupling. The full icon model code is publicly available at gitlab.dkrz.de/icon/icon-model under BSD 3-clause license The full msgwam submodule code is publicly available at gitlab.dkrz.de/atmodynamics-goethe-universitaet-frankfurt/msgwam-release under CC-BY-SA 4.0 license This work is a contribution to the research areas B06 (Small scale dynamics), B07 (Impact of cirrus clouds on tropopause structure) and Z03 (Joint model development and modelling synthesis) of the Collaborative Research Centre TRR 301 "The Tropopause Region in a Changing Atmosphere" Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) Project-ID 428312742, as well as to the research areas W1 (Gravity Wave Parameterisation for the Atmosphere) and S2 (Improved parameterisations and numerics in climate models) of the Collaborative Research Centre TRR 181 "Energy Transfer in Atmosphere and Ocean" funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) Project-ID 274762653.