Integration of an ecosystem module into the finite element sea-ice ocean model
In coupled ocean-biogeochemical models, the ocean model has a large influence on the distribution of the biological tracers. Biogeochemical models are traditionally coupled to ocean models based on the finite difference method, but another option is to employ an unstructured-mesh ocean model. This makes it possible to take advantage of for instance aligning the mesh with bathymetry or refining it in areas of interest without the loss of accuracy that nesting introduces. Here we present initial results of a coupling between the Finite Element Sea-ice Ocean Model (FESOM) and the biogeochemical model REcoM2, with special attention on the Southern Ocean. Surface fields of nutrients, chlorophyll a and net primary production were compared to available data sets with focus on spatial distribution and seasonal cycle. We saw that the model produces realistic distributions, especially regarding the mean spatial distribution of net primary production and surface chlorophyll a concentration, whereas the surface iron concentration became vey low in the Pacific, causing extensive iron limitation in the Area. The mean seasonal cycle was in good agreement with observations, but spring blooms occurred too early in the Polar Regions. For the Southern Ocean we showed that this early bloom is caused by nutrient limitation dominating in the area between 40 and 60 degrees south. Light limitation was on the contrary the main limiting factor in the seasonally ice covered area south of 60 degrees south, All in all, the model is similar in performance to other models of equal complexity and well suited for studies of the Southern Ocean.
AWI Organizations > Climate Sciences > Climate Dynamics