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During the second phase (2003-2006) of the Mediterranean ocean Forecasting System Project (MFS) named Toward Environmental Predictions (MFSTEP) one of the three major aims was the development of numerical forecasting systems. In this context a generic Biogeochemical Flux Model (BFM) was developed and coupled with hydrodynamic models already operating at basin scale as well as in regional areas. In the Eastern Mediterranean basin the BFM was coupled with the Aegean Levantine Eddy Resolving MOdel (ALERMO). The BFM is a generic highly complex model based on ERSEM and although a detailed description of the model and its components is beyond the scope of this work, a short overview of the main processes, laying emphasis on the parameter values used is presented. In addition the performance of the model is evaluated with some preliminary results being qualitatively compared against field observations. The model in its present form is rather promising and reproduces all important major features although there are some slight inefficiencies mostly related to primary and bacterial productivity rates. [ABSTRACT FROM AUTHOR]

A 3-D full life cycle population model for the North Aegean Sea (NAS) anchovy stock is presented. The model is two-way coupled with a hydrodynamic–biogeochemical model (POM–ERSEM). The anchovy life span is divided into seven life stages/age classes. Embryos and early larvae are passive particles, but subsequent stages exhibit active horizontal movements based on specific rules. A bioenergetics model simulates the growth in both the larval and juvenile/adult stages, while the microzooplankton and mesozooplankton fields of the biogeochemical model provide the food for fish consumption. The super-individual approach is adopted for the representation of the anchovy population. A dynamic egg production module, with an energy allocation algorithm, is embedded in the bioenergetics equation and produces eggs based on a new conceptual model for anchovy vitellogenesis. A model simulation for the period 2003–2006 with realistic initial conditions reproduced well the magnitude of population biomass and daily egg production estimated from acoustic and daily egg production method (DEPM) surveys, carried out in the NAS during June 2003–2006. Model simulated adult and egg habitats were also in good agreement with observed spatial distributions of acoustic biomass and egg abundance in June. Sensitivity simulations were performed to investigate the effect of different formulations adopted for key processes, such as reproduction and movement. The effect of the anchovy population on plankton dynamics was also investigated, by comparing simulations adopting a two-way or a one-way coupling of the fish with the biogeochemical model. [ABSTRACT FROM AUTHOR]

Operational monitoring and forecasting of marine environmental conditions is a necessary tool for the effective management and protection of the marine ecosystem. It requires the use of multi-variable real-time measurements combined with advanced physical and ecological numerical models. Towards this, a FerryBox system was originally installed and operated in the route Piraeus–Heraklion in 2003 for one year. Early 2012 the system was upgraded and moved to a new high-speed ferry traveling daily in the same route as before. This route is by large traversing the Cretan Sea being the largest and deepest basin (2500 m) in the south Aegean Sea. The HCMR Ferry Box is today the only one in the Mediterranean and thus it can be considered as a pilot case. The analysis of FerryBox SST and SSS in situ data revealed the presence of important regional and sub-basin scale physical phenomena, such as wind-driven coastal upwelling and the presence of a mesoscale cyclone to the north of Crete. In order to assess the impact of the FerryBox SST data in constraining the Aegean Sea hydrodynamic model which is part of the POSEIDON forecasting system, the in situ data were assimilated using an advanced multivariate assimilation scheme based on the Singular Evolutive Extended Kalman (SEEK) filter, a simplified square-root extended Kalman filter that operates with low-rank error covariance matrices as a way to reduce the computational burden. Thus during the period mid-August 2012–mid January 2013 in addition to the standard assimilating parameters, daily SST data along the ferryboat route from Piraeus to Heraklion were assimilated into the model. Inter-comparisons between the control run of the system (model run that uses only the standard data set of observations) and the experiment where the observational data set is augmented with the FerryBox SST data produce interesting results. Apart from the improvement of the SST error, the additional assimilation of daily of FerryBox SST observations is found to have a significant impact on the correct representation of the dynamical dipole in the central Cretan Sea and other dynamic features of the South Aegean Sea, which is then depicted in the decrease of the basin wide SSH RMS error. [ABSTRACT FROM AUTHOR]

Abstract: The North Aegean inter-annual productivity variability was investigated, by means of a coupled hydrodynamic/biogeochemical model simulation, over a multi-year (1985–2001) period covering the Eastern Mediterranean Transient (EMT). The EMT was a historically significant period (1987–1994), characterized by the massive formation of dense waters in the Aegean and their subsequent southward spreading to the Eastern Mediterranean. Our findings suggest that during the dense water formation events, deep nutrient rich water is exported to the South, affecting the N. Aegean nutrient pool. We show that the open sea productivity variability, driven by the deep nutrient pool entrainment to the euphotic zone, is related to both vertical mixing and nutrient fluxes, induced by thermohaline circulation variability. A negative correlation appears between the two processes, as stronger vertical mixing triggers a higher nutrient export. Process oriented experiments adopting maximum and minimum nutrient fluxes to the Southern Aegean revealed a significant impact on the nutrient pool, counterbalancing the effect of different vertical mixing on primary production. The model results presented good correlation with available satellite SST and Chl-a data. The impact of precipitation and BSW inflow variability on the Aegean salinity and dense water formation was investigated, showing a significant contribution by both preconditioning factors. [Copyright &y& Elsevier]