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This paper describes Nemo-Nordic 2.0, an operational marine model for the Baltic Sea. The model is used for both near-real-time forecasts and hindcast purposes. It provides estimates of sea surface height, water temperature, salinity, and velocity, as well as sea ice concentration and thickness. The model is based on the NEMO (Nucleus for European Modelling of the Ocean) circulation model and the previous Nemo-Nordic 1.0 configuration by. The most notable updates include the switch from NEMO version 3.6 to 4.0, updated model bathymetry, and revised bottom friction formulation. The model domain covers the Baltic Sea and the North Sea with approximately 1 nmi resolution. Vertical grid resolution has been increased from 3 to 1 m in the surface layer. In addition, the numerical solver configuration has been revised to reduce artificial mixing to improve the representation of inflow events. Sea ice is modeled with the SI3 model instead of LIM3. The model is validated against sea level, water temperature, and salinity observations, as well as Baltic Sea ice chart data for a 2-year hindcast simulation (October 2014 to September 2016). Sea level root mean square deviation (RMSD) is typically within 10 cm throughout the Baltic basin. Seasonal sea surface temperature variation is well captured, although the model exhibits a negative bias of approximately - 0.5 ∘ C. Salinity RMSD is typically below 1.5 g kg -1. The model captures the 2014 major Baltic inflow event and its propagation to the Gotland Deep. The model assessment demonstrates that Nemo-Nordic 2.0 can reproduce the hydrographic features of the Baltic Sea. [ABSTRACT FROM AUTHOR]

The Finnish Meteorological Institute is currently running separate models to make operational predictions of water level, ice cover, waves and water circulation. The trend has long been towards more general and coupled models to better simulate the interplay of ocean, ice and atmosphere. We are in the process of adopting Nemo to fulfill these needs. We have set up the Nemo Nordic configuration that covers the Baltic Sea and developed a Kara Sea configuration and are running these pre-operationally. In addition we have experimented with hindcast runs with both NEMO 3.6 and 4.0.In this work we will evaluate the skill of NEMO 3.6 and 4.0 on the Baltic Sea in terms of sea level, sea surface temperature, and the extent and mass of sea ice. The ice parameters will also be compared to results from our established multicategory sea ice model HELMI. We will also look into the sensitivity of these parameters to choices made in the model numerics. [ABSTRACT FROM AUTHOR]