First application of unstructured grids to modelling large-scale thermohaline circulation: the North Atlantic circulation of the finite-element ocean model (FEOM)

• Main Authors: Danilov, Sergey, Kivman, G., Schröter, Jens
• Format: Conference Object
• Language: unknown
• Published: 2004
• Subjects: North Atlantic
• Online Access: https://epic.awi.de/id/eprint/10668/; https://hdl.handle.net/10013/epic.21137

We describe the finite-element ocean circulation model (FEOM) and its potential (local mesh refinement, sloping bottom in the $z$-coordinate discretization), and also present comparison of the North Atlantic circulation obtained with the FEOM with the results of other models at comparable or finer resolution (in particular, with those participating in the DYNAMO and DAM\'EE-NAB intercomparison projects). Due to flexibility in local mesh refinement the FEOM provides a tool for modelling the influence of small scale phenomenaunresolved by current climate models on large scale ocean circulation.The FEOM was run for ten years on an unstructured mesh covering an area of the Atlantic between 7 and 80 N$^{0}$at resolution varying between 0.2$^0$--2$^0$. The model was forced byNCEP winds and relaxation to the seasonal Levitus climatology at the surface. Open boundaries were closed and buffer zones were introduced in their vicinity where potential temperature and salinity are relaxed to climatology.The model reproduces overturning meridional circulation of 15.5 Svwith maximum transport located at 36$^0$ N and a depth of 1000 m.The annual mean meridional heat flux is about 1 PW. The annual meantransports of the Gulf Stream and Deep Western Boundary Current are of 37 Sv and 17 Sv respectively with core velocities of about 1 m/s and 12 cm/s at a latitude of 27$^0$ N. The model is also able to maintain the Mediterranean salinity tongue up to 20$^0$ W when a relaxation to the Levitus climatology within a buffer zone of 3$^0$ around the Strait of Gibraltar is used.