The study presents seasonal variability of currents in the southern part; of the Gulf of Trieste. A time series analysis of current's and wind stress for the period 2003-2006, which were measured by the coastal oceanographic buoy, was conducted. A comparison between these data and results obtained from a numerical model of circulation in the Gulf was performed to validate model results. Three different approaches were applied to the wind data to determine the wind stress. Similarities were found between Kondo and Smith approaches while the method of Vera shows differences which were particularly noticeable for lower (= 1 m/s) and higher wind speeds (= 15 m/s). Mean currents in the surface lawyer are generally outflow currents from the Gulf due to wind forcing (bora). However in all other depth layers inflow currents are dominant. With the principal component analysis (PCA) major and minor axes were determined for all seasons. The major axis of maximum variance in years between 2003 and 2006 is prevailing in NE-SW direction, which is parallel to the coastline. Comparison of observation and model results is showing that currents are similar (in direction) for the surface and bottom layers but are significantly different for the middle layer (5-13 m). At a, depth between 14-21 m velocities are comparable in direction as well as in magnitude even though model values are higher. Higher values of modelled currents at the surface and near the bottom are explained by higher values of wind stress that: were used in the model as driving input with respect to the stress calculated from the measured winds. Larger values of modelled currents near the bottom are related to the larger inflow that needs to compensate for the larger modelled outflow at the surface. However, inspection of the vertical Structure of temperature, salinity and density shows that the model is reproducing a weaker density gradient which enables the penetration of the outflow surface currents to larger depths.
