ABSTRACT
Numerical ecosystem models, as operational tools, may directly apply to problems of environmental management, predicting the response of natural systems to perturbations and modifications of various kinds. Since dynamics are described in some detail, the model may provide insight into the governing mechanisms influencing the functioning of the ecosystem described in a companion paper [1]. Pagasitikos is a semi-enclosed gulf situated on the western part of Aegean Sea north of the island of Evia connected at the south with the Aegean Sea through the 5.5 km wide, narrow channel of Trikeri. The predominant weak winds of the area result in small to moderate water currents while renewal occurs mainly through the deep-water layer of the communication channel with Aegean Sea. During winter months the water mass of Pagasitikos is fairly mixed, forming a two-layer thermocline for the rest of the year with the exception of August when three layers are observed. Inflows of fresh waters in the areas of Volos and Almiros are also observed during winter and spring adding to the complexity of the system. In this work the capability of a high-resolution hydrodynamic model based on Princeton Ocean Model (POM) to describe the phenomenology of Pagasitikos is investigated. Comparison with direct current measurements show good agreement indicating that the model can successfully reproduce the general circulation characteristics of the area aiding in the understanding of the complicated hydrological structure and circulation patterns appearing within the area. In addition the effect of high frequency wind forcing is explored through the comparison with surface forcing specified from monthly mean climatological data.
