Setting up the NEMO (Nucleus for European Modeling of the Ocean) for Baltic Sea region - open boundary conditions

The Baltic Sea is inland, Shelf Sea in northern part of Europe. It is shallow with average depth of 52 meters and deepest point 459 meters located at Landsort Deep. Baltic Sea is connected with North Sea via the Danish Straits (comprising of Great Belt, Little Belt and Øresund). These systems ensure only limited exchange between oceanic waters and seawaters, which affect the low salinity in Baltic reservoir. Runoff from surrounding lands (approximately 200 rivers) and positive difference of precipitation minus evaporation additionally refreshes water and makes Baltic a brackish sea. The only charge of salt comes from the North Sea with so-called inflows or less frequent occurring Major Baltic Inflows (MBI). This exchange between Danish Straits is the key for properly working simulation. In this work the tool, well known as NEMO, was used to perform the numerical simulation for the Baltic Sea area. This presentation is focused on the first stage of validation of the model results for the Baltic Sea region where influence of open boundary conditions is noticeable as soon as possible. The main change in the model is the assimilation of sea surface height in Kattegat area. Also water outflow mass controlling from the Baltic Sea has been introduced. The properly working open boundary conditions affect the water exchange between Baltic Sea and North Sea, thus the MBI and minor salty inflows are well represented. This is very important part in modeling the Baltic
Sea, where narrow Danish Straits limits the water exchange which controls the salt budget, adding the salt with inflows and receiving brackish outflow out to the Ocean. This work presents comparison between model output with results measured in situ and from other validated model, the period which is compared is the Major Baltic Inflow in the beginning of 1993.