ICON model output from Arctic regional climate downscaling simulations for PolarRES and CORDEX-CMIP6

This dataset includes model output from simulations with the ICON weather and climate model (https://www.icon-model.org/, Zängl et al. 2015, https://doi.org/10.1002/qj.2378). ICON was run in limited-area climate mode (ICON-CLM, Pham et al. 2021, https://doi.org/10.5194/gmd-14-985-2021) on a regional Arctic domain with 0.1° (~11km) horizontal resolution, aligned with the domain specified by CORDEX (https://cordex.org/domains/region-11-arctic/). The simulations were produced within the PolarRES project (https://polarres.eu/) and are registered within the CORDEX-CMIP6 framework (https://wcrp-cordex.github.io/simulation-status/). The simulations dynamically downscale the boundary forcing data that come from ERA5 (for 2000-2022, Hersbach et al. 2020, https://doi.org/10.1002/qj.3803) and two CMIP6 models: CNRM-ESM2-1 (https://doi.org/10.22033/ESGF/CMIP6.1391) and NorESM2-MM (https://doi.org/10.22033/ESGF/CMIP6.608), using the historical runs for 1985-2014 and the ssp370 runs for 2015-2099. Pre-processed boundary forcing files were provided by the CLM-Community (https://www.clm-community.eu/) on the DKRZ Levante HPC (under /arch/pd1309/forcings/reanalyses/ERA5 by Burkhardt Rockel and Beate Geyer; and under /pool/data/CLMcom/ICON-CLM/gcm/forcing by Patrick Ludwig). ICON model version 2.6.6 was used for the ERA5 and CNRM-ESM2-1 downscaling, while ICON v2024.01 was used for the NorESM2-MM downscaling when it became available as the first open-source release of ICON. The simulations employed grid-point nudging at the upper boundary, starting at 5 km height. The simulations were run on the DKRZ Levante HPC. The SPICE toolbox (Rockel and Geyer 2022, https://doi.org/10.5281/zenodo.7298390) was used to organize the ICON simulations. The data included here is a subset of the data that will be published in standardized form in the ESGF within CORDEX-CMIP6. Here, monthly means of the CORDEX core variables (tas, tasmin, tasmax, pr, evspsbl, huss, hurs, ps, psl, sfcWind, uas, vas, clt, rsds, rlds, siconca) as well as fixed parameters (orog, sftlf) are provided. Additionally, the grid files and scripts with parameter settings are included to document the configuration of the ICON simulations. The monthly files were quantized to five significant digits using NCO precision-preserving compression (ncks --ppc default=5), reducing file size with only minor precision loss.