A New High-Resolution Ocean Reanalysis for the Baltic Sea: Insights into Ocean Dynamics

Ocean reanalyses provide a valuable source of data for understanding the dynamics of the ocean, climate studies and practical applications. We introduce a new CMEMS high-resolution ocean reanalysis for the Baltic Sea for the period from 1993 to 2021. The reanalysis is an upgrade of the existing CMEMS products BALTICSEA_REANALYSIS_PHY_003_011 and BALTICSEA_REANALYSIS_BIO_003_012 and introduces numerous changes including higher horizontal resolution, approximately 1.9 km, a new versions of ocean, ice and biogeochemical models, and a new data assimilation scheme.

We have analyzed the reanalysis data to assess the performance of the new reanalyses focusing on the ocean dynamics. We found that the high resolution of the reanalysis allowed us to detect finer-scale features in the data, such as mesoscale eddies, that were not apparent in lower resolution dataset as well as improve the ocean currents.

We also used the reanalysis to study the occurrence and evolution of salt water inflows from the North Sea. Our results suggest that the high resolution of the reanalysis enables more accurate predictions of these events.

Overall, our study demonstrates the utility of the new high-resolution ocean reanalysis for understanding the dynamics of the Baltic Sea and improving our ability produce a physically consistent combination of model and observations.