VIKING20X-JRA-short (Biastoch et al., 2021) is part of a series of VIKING20X simulations under JRA55-do atmospheric forcing. It is based on a restart from a pre-spun experiment in 1980 (VIKING20X-CORE; see Biastoch et al., 2021) and integrated for the period 1980 to 2019 in the framework of the RACE–Synthesis: Regional Atlantic Circulation and Global Change (https://race-synthese.de). The applied atmospheric forcing JRA55-do (Tsujino et al., 2020, http://doi.org/10.5194/gmd-13-3643-2020) builds on the Japanese reanalysis product JRA-55 with improvements through the implementation of satellite and several other reanalysis products.

                Details of the Configuration:
                - eddy-rich 1/20° nest using the two-way nesting technique Adaptive Grid Refinement In Fortran (AGRIF; http://doi.org/10.1016/j.cageo.2007.01.009) that covers the Atlantic Ocean from 33.5° S to ∼65° N embedded in a 1/4° resolution global grid
                - initialization from a pre-spun experiment in 1980
                - time step refinement factor 3 between host and nest
                - momentum advection scheme in vector form with Hollingsworth correction, conserving both energy and enstrophy
                - tracer advection as two-step flux corrected transport, total variance dissipation scheme
                - linearized filtered free surface
                - weak sea surface salinity restoring towards Levitus WOA98 (piston velocity 12.2 m/yr), suppressed under sea-ice
                - thermodynamic, dynamic sea-ice model LIM2 (https://doi.org/10.1029/97JC00480) with viscous-plastic rheology
                - turbulent kinetic energy scheme
                - bi-Laplacian lateral viscosity
                - non-linear bottom friction

                Note of advise on re-using the provided simulation output data
                We recommend to only use the high-resolution simulation output data from the 1/20 degree nested region for any analysis (nest file names "1_VIKING20X.L46-KKG36107B_*.nc"). The simulation was designed to improve the understanding of specific key processes in the Atlantic Ocean and their effect on the large scale and inter-hemispheric circulation in the Atlantic.
                The simulation results can only be interpreted in this context and are not necessarily applicable to other arbitrary research questions on ocean and climate dynamics. In particular, the output fields of the global simulation at coarser resolution (host file names "VIKING20X.L46-KKG36107B_*.nc") must be understood as an interactive boundary condition to the focus region of the nest and are here provided for completeness only. For questions in this regard we recommend to contact datamanagement@geomar.de and generally encourage potential users to reach out to us for clarification.

                A detailed description of the configuration and experiments is given in Biastoch et al. (2021):
                Biastoch, A., F. U. Schwarzkopf, K. Getzlaff, S. Rühs, T. Martin, M. Scheinert, T. Schulzki, P. Handmann, R. Hummels, and C. W. Böning, 2021, Regional Imprints of Changes in the Atlantic Meridional Overturning Circulation in the Eddy-rich Ocean Model VIKING20X, Ocean. Sci., 17, 1177–1211, http://doi.org/10.5194/os-17-1177-2021