A study of the hydrographic conditions in the Adriatic Sea from numerical modelling and direct observations (2000–2008)

Abstract. The inter-annual variability of Adriatic Sea hydrographic characteristics is investigated by means of numerical simulation and direct observation. The period under investigation runs from the beginning of 2000 to the end of 2008. The model used to carry out the simulation is derived from the primitive equation component of the Adriatic Forecasting System (AFS). The model is based on the Princeton Ocean Model (POM) adapted in order to reproduce the features of the Adriatic. Both numerical findings and observations agree in depicting a strong inter-annual variability in the entire Adriatic Sea and its sub-basins. Nevertheless, two model deficiencies are identified: an excessive vertical/horizontal mixing and an inaccurate representation of the thermohaline properties of the entering Mediterranean Waters. The dense water formation process has been found to be intermittent. In addition to inter-annual variability, a long-scale signal has been observed in the salinity content of the basin as a consequence of a prolonged period of reduced Po river runoff and high evaporation rates. As a result, the temperature and salinity of the northern Adriatic dense water vary considerably between the beginning and the end of the period investigated.