The assimilation of satellite absorption and glider data into novel bio-optical module coupled to ERSEM on the North-West European Shelf

The North-West European Shelf (NWES) is a very important region for both European economy and the marine ecosystem impact on carbon cycle. We introduced a novel spectrally resolved (stand-alone) bio-optical module into the European Regional Seas Ecosystem Model (ERSEM) to improve how ERSEM represents primary productivity on the NWES. The bio-optical module also gives us the capability to provide biogeochemical feedback on physics, in particular the improved representation of under-water light field can be used to improve the temperature profiles. We used the bio-optical module to assimilate novel Phytoplankton Functional Type (PFT) absorption satellite product into the coupled NEMO-FABM-ERSEM model and we have shown that absorption data assimilation has some advantages over the currently established PFT chlorophyll-a assimilation. In particular the PFT absorption assimilation outperforms PFT chlorophyll assimilation in how it represents the under-water light field and some ecosystem indicators (ie. PFT chlorophyll-to-carbon ratios). We further implemented the bio-optical module in the context of combined assimilation of glider profiles (oxygen, total chlorophyll) and satellite data.