Project: Middle atmosphere localized gravity wave forcing: Formation, impact and long-term evolution - The project (https://www.physgeo.uni-leipzig.de/institut-fuer-meteorologie/forschung/arbeitsgruppemeteorologiederhochatmosphaere/forschung/forschungsprojekte) is a cooperation of Leipzig University, Institute for Meteorology, Leipzig, Ger­many (LIM) and the Department of Atmospheric Physics, Faculty of Mathematics and Physics, Charles University in Prague, Czech Republic (DAP). It is supported by Deutsche Forschungsgemeinschaft under grant JA 836/47-1 during 2021 – 2023 (https://gepris.dfg.de/gepris/projekt/452408779). Project PIs are Prof. Christoph Jacobi (LIM) and Prof. Petr Pisoft (DAP). Project scientists are Dr. Khalil Karami (LIM, b381561), Dr. Petr Sacha (DAP, b381114), and Zuzana Prochazkova, MSc. (DAP, b381585). The project focuses on the detection, analysis, and modelling of stratospheric gravity wave (GW) hotspots and their effect on middle atmospheric dynamics. We will identify GW hotspots on the basis of observations, reanalysis data and model output by analysing different GW parameters and background conditions. From these analyses, we will deduce possible GW sources as well as meteorological conditions that favour the generation of GW hotspots. Based on the results from the datasets partly covering several decades, we will also investigate the temporal development of the GW hotspots to investigate in how far the GW hotspot activity has changed during the last decades. We perform experiments with UA-ICON model to study the effects of the detected GW hotspots on the dynamics of the atmosphere, up to 100 km of altitude. Based on these results, specific circulation responses, which are induced by the local GW forcing, will be derived. Summary: We utilize the ICON version 2.6.3 with upper-atmosphere extension as distributed by the German weather service (DWD). The ICON model is a collaborative project of DWD and the Max Planck Institute for Meteorology, striving at providing a unified modeling system to seamlessly allow simulations from climatological time scales to large-eddy simulations as well as for global numerical weather prediction (Zangl et al., 2015). In addition to the upper-atmosphere physics package implemented in UA-ICON, the dynamical core is extended from the shallow to deep atmosphere dynamics (Borchert et al., 2019). In our setup, the UA-ICON model is set up with the horizontal resolution of R2B4, which corresponds to a grid mesh of approximately 160 km with 120 levels up to a height of approximately 147 km. The time step of the simulation is 360s. The data output interval is set to 6 h, which is essential in the calculations of the Eliassen-Palm (EP) flux divergence. The mid-monthly sea surface temperature (SST) and sea ice concentration (SIC) values produced by the Program for Climate Model Diagnosis and Intercomparison (PCMDI) for the Atmosphere Model Intercomparison Project (AMIP, Taylor et al. (2000)) served as lower boundary condition data. Interactive chemistry was not used in the current simulation. Instead, the concentrations of CO2, CH4, N2O, CFC-11, and CFC-12 were taken from the historical greenhouse gas volume mixing ratios for CMIP6 (Meinshausen et al., 2017). The atmospheric ozone concentrations were prescribed based on the input4MIPs project (https://esgf-node.llnl.gov/search/input4mips).