Effects of lateral processes on the seasonal water stratification of the Gulf of Finland: 3-D NEMO-based model study

Abstract

Abstract. This paper tries to fill the gaps in knowledge of processes affecting the seasonal water stratification in the Gulf of Finland (GOF). We used state-of-the-art modeling framework NEMO aimed for oceanographic research, operational oceanography, seasonal forecasting and climate studies to build an eddy resolving model of the GOF. To evaluate the model skill and performance two different solutions where obtained on 0.5 km eddy resolving and commonly used 2 km grids for one year simulation. We also explore the efficacy of nonhydrostatic effect (convection) parameterizations available in NEMO for coastal application. It is found that the solutions resolving sub-mesoscales have a more complex mixed layer structure in the regions of GOF directly affected by the upwelling/downwelling and intrusions from the open Baltic Sea. Presented model estimations of the upper mixed layer depth are in a good agreement with in situ CTD data. A number of model sensitivity tests to the vertical mixing parameterization confirm the model robustness.