ICON is a modeling framework for weather, climate, and environmental prediction. It solves the full three-dimensional non-hydrostatic and compressible Navier-Stokes equations on an icosahedral grid and allows seamless predictions from local to global scales. More information about ICON is available at https://www.icon-model.org/. The ICON Code is documented in GitLab: https://gitlab.dkrz.de/icon/icon-model. Release information: RELEASE_NOTES.md

ICON is a modeling framework for weather, climate, and environmental prediction. It solves the full three-dimensional non-hydrostatic and compressible Navier-Stokes equations on an icosahedral grid and allows seamless predictions from local to global scales. More information about ICON is available at https://www.icon-model.org/. The ICON Code is documented in GitLab: https://gitlab.dkrz.de/icon/icon-model.

ICON is a modeling framework for weather, climate, and environmental prediction. It solves the full three-dimensional non-hydrostatic and compressible Navier-Stokes equations on an icosahedral grid and allows seamless predictions from local to global scales. More information about ICON is available at https://www.icon-model.org/. The ICON Code is documented in GitLab: https://gitlab.dkrz.de/icon/icon-model.

ICON is a modeling framework for weather, climate, and environmental prediction. It solves the full three-dimensional non-hydrostatic and compressible Navier-Stokes equations on an icosahedral grid and allows seamless predictions from local to global scales. More information about ICON is available at https://www.icon-model.org/. The ICON Code is documented in GitLab: https://gitlab.dkrz.de/icon/icon-model. Release information: RELEASE_NOTES.md

ICON is a modeling framework for weather, climate, and environmental prediction. It solves the full three-dimensional non-hydrostatic and compressible Navier-Stokes equations on an icosahedral grid and allows seamless predictions from local to global scales. More information about ICON is available at https://www.icon-model.org/. The ICON Code is documented in GitLab: https://gitlab.dkrz.de/icon/icon-model. Release information: RELEASE_NOTES.md

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.

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 non-orographic gravity waves scheme is not used in this simulation. 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.

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 non-orographic gravity waves scheme is not used in this simulation. 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.

The EU project European Eddy RIch Earth System Models (EERIE) is developing a new generation of Earth System Models (ESMs) that explicitly resolve ocean mesoscale dynamics, an essential but still poorly explored part of the climate system. By using recent advances in computing and model design, EERIE aims to improve long-term climate simulations, including variability, extremes, and potential tipping points influenced by mesoscale ocean processes. ICON in Sapphire configuration is one of these new models. Developed at the Max Planck Institute for Meteorology, ICON couples the atmosphere, land, ocean, and sea ice at kilometer-scale resolution. It resolves deep atmospheric convection and captures mesoscale to sub-mesoscale ocean eddies, with the option to refine the global ocean grid locally as a “computational telescope.” The atmospheric component uses a nonhydrostatic icosahedral C grid with a hybrid sigma-z vertical coordinate and parameterizes only unresolved processes (radiation, microphysics, turbulence). The ocean component shares the same grid and solves the hydrostatic Boussinesq equations, using only a subset of parameterizations such as vertical mixing and velocity dissipation. Sea ice is included via FESIM dynamics and a simplified thermodynamic scheme. Ocean biogeochemistry is represented by HAMOCC6, simulating more than 20 tracers. The land component, JSBACH 4, provides surface fluxes and simplified hydrology with prescribed vegetation. All components are coupled through the YAC coupler (v2.4.2). The main simulations were preceded by a 40-year spin-up period using 1950 CMIP6 forcing. From the spin-up’s final state, two parallel simulations were started: a 100-year control run and a historical run. The control run is used to identify and quantify model drift, ensuring that any long-term changes in the historical simulation could be attributed to variations in radiative forcing rather than internal drift.

The EU project European Eddy RIch Earth System Models (EERIE) is developing a new generation of Earth System Models (ESMs) that explicitly resolve ocean mesoscale dynamics, an essential but still poorly explored part of the climate system. By using recent advances in computing and model design, EERIE aims to improve long-term climate simulations, including variability, extremes, and potential tipping points influenced by mesoscale ocean processes. ICON in Sapphire configuration is one of these new models. Developed at the Max Planck Institute for Meteorology, ICON couples the atmosphere, land, ocean, and sea ice at kilometer-scale resolution. It resolves deep atmospheric convection and captures mesoscale to sub-mesoscale ocean eddies, with the option to refine the global ocean grid locally as a “computational telescope.” The atmospheric component uses a nonhydrostatic icosahedral C grid with a hybrid sigma-z vertical coordinate and parameterizes only unresolved processes (radiation, microphysics, turbulence). The ocean component shares the same grid and solves the hydrostatic Boussinesq equations, using only a subset of parameterizations such as vertical mixing and velocity dissipation. Sea ice is included via FESIM dynamics and a simplified thermodynamic scheme. Ocean biogeochemistry is represented by HAMOCC6, simulating more than 20 tracers. The land component, JSBACH 4, provides surface fluxes and simplified hydrology with prescribed vegetation. All components are coupled through the YAC coupler (v2.4.2). The main simulations were preceded by a 40-year spin-up period using 1950 CMIP6 forcing. From the spin-up’s final state, two parallel simulations were started: a 100-year control run and a historical run. The control run is used to identify and quantify model drift, ensuring that any long-term changes in the historical simulation could be attributed to variations in radiative forcing rather than internal drift. The historical simulation employed CMIP6 historical forcing spanning from 1950 to 2014, running for a total of 65 years. Only volcanic aerosol forcing was taken from CMIP5.