Numerical Simulation of Rijeka Bay Water Dynamics for Most Common Winds

The goal of this paper is to quantify the atmospheric influence, i.e. the influence of wind in particular, on the sea dynamics in the Rijeka Bay (Adriatic Sea). This quantification is important for city sewage disposal and dispersion as well as surface pollution dispersion. We compare the effect of jugo (sirocco) and bora winds on a calm period. The resulting simulations show that the bora conveys the surface layer of sea water out of the bay through the Middle and the Great Gate while deep cold water enters the bay through the same gates. The mean vertical upward velocity component close to the coast is about 1 mm s. This is sufficient to rise cold water near the city of Rijeka to the surface in three hours and to significantly cool the surface layer during summer. For the south-east wind (jugo) the situation is reverse: the warmer surface sea water enters the bay through the Middle and the Great Gate, while the colder bottom sea water exits the bay through the Middle and the Great Gate, accumulating the warmer sea water in the bay. In the case of no wind the surface velocity vectors (at depths of 0.5 m) are disordered and do not follow any particular pattern while the movements at 12 m, 24 m, 36 m, 48 m, and 60 m show dominant flow from the western coast (of the island Krk) toward the eastern coast of the Istrian peninsula.