Multi-scale validation of a coupled physical biogeochemical model of the Northern Adriatic sea

This thesis evaluates a coupled physical and biogeochemical model of the Northern Adriatic Sea. The system links the NEMO circulation model with the Biogeochemical Flux Model and is run at 1 km resolution with 47 vertical layers for the years 2000 to 2009. The setup includes realistic bathymetry, benthic and pelagic coupling, and detailed river inputs, with special focus on the Po River. The aim is to assess how well the model reproduces sea surface temperature, stratification, dense water formation, chlorophyll, and dissolved oxygen. Validation uses satellite data, CTD observations, cruise measurements, and river discharge records. The evaluation includes time series analysis, seasonal decomposition, skill metrics, spatial error maps, target and Taylor diagrams, and spectral tools. The Region Of Freshwater Influence created by the Po plume is identified with clustering and bio-geophysical profiles within the ROFI are validated against in-situ vertical casts. Vertical profiles and bottom conditions are also examined. The model captures the seasonal cycle and large scale patterns of sea surface temperature, though local biases near the Po delta and coastal areas are identified. The model captures long-term variability and the inversion of the anomalous net downward heat flux in 2006. Chlorophyll patterns are reproduced, but the model tends to exaggerate the costal dynamics while underestimating open-sea concentrations. A shift in chlorophyll around 2007 is found, matching a change in Po River discharge. Dense water formation events and their downslope movement are realistically represented, with strong year to year variability. Bottom oxygen analysis shows exaggerated consumption near the benthic layer, especially evident near-coast. Overall, the model performs well but can be improved through better river forcing, refined coastal processes, enhanced sediment representation, and parameter tuning.