Application of the Bryan-Cox-type ocean model to reproduce synoptic and mesoscale variability of the Irbe Strait salinity front

Abstract

The Bryan-Cox Ocean General Circulation Model (OGCM) was applied to simulate synoptic and mesoscale variability of salinity distribution in the Irbe Strait. The narrow and shallow Irbe Strait, in which resides a permanent salinity front, connects two sub-basins of the Baltic Sea the Baltic Proper and the Gulf of Riga. The model resolution most commonly applied in Baltic Sea studies about 2.5 nm horizontally and 5 m vertically was used. Simulated salinity fields were compared with mesoscale measurements on three occasions during a 10-day period. The model reproduced qualitatively the spatial structure of the permanent salinity front and its temporal evolution. Dynamics of the frontal zone were captured in a smooth way. The applied spatial resolution of the model did not resolve the following: detailed current dynamics in the lateral boundary layer, strength of cross-strait circulation, intensity and sharpness of convergence zones and the level of relative vorticity. Failure to reproduce mesoscale features in the frontal zone may lead to unsuccessful long-term simulations of general circulation and water mass formation in the Baltic Sea.