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).

                Here we conduct 30-year long time-slice experiments with the UA-ICON model by employing repeated annual cycles of SST, SIC, and greenhouse gases of the year 1985. This year is appointed as both El-Nino southern oscillation and Pacific decadal oscillation were in their neutral phase and no major volcano eruption has occurred, hence conditions in this year can serve as a useful proxy for the multi-year mean conditions and an estimate of their internal variability. The control run is carried out where both the sub-grid scale orography (SSO) scheme and non-orographic gravity waves scheme are used. In UA-ICON, the entire SSO drag is treated after Lott and Miller (1997), and the non-orographic GW drag parameterization is based on Warner and McIntyre (1996) and Scinocca
                (2003). It is worthwhile to mention that in addition to the orographic GWD, the SSO scheme used in UA-ICON also contains the effect of low-level blocking and wake drag.

                As the simulations are the time-slice experiments, only the months , days and hours have their true/usual meanings and years in the name of output files do not have their true/usual meaning. In other words, all the outputs files with different years (1986, 1987, ..., 2015) are identical to year 1985 as identical boundary conditions as year 1985 are used to simulate them. For example, 0001 and 0002 represent the first and second years of simulations, respectively and 0030 is the last (30) year.