摘要：For the Gulf of Finland, we carried out the EOF (empirical orthogonal functions) analysis of hourly forecasts from the Baltic Sea operational HIROMB-SMHI model for the period 2006–2008. It is possible to distinguish two regions with a specific regime of circula- tion variability. The western region behaves like a wide channel. Dominant EOF modes at different sections have similar patterns and their time-dependent amplitudes are well correlated. A prevailing mode of currents (23%–42% of the variance) is barotropic (unidi- rectional over the whole section) and its oscillation (spectral peak at 24 h) is related to the water storage variation of the Gulf. A two-layer flow pattern (surface Ekman transport with deeper compensation flow, 19%–22%) reveals both inertial and lower frequencies. High- est outflow of surface waters occurs during north-easterly winds. The eastern wider region has more complex flow dynamics and only patterns that are nearly uniform over the whole Gulf were detected here. On the sea surface, quasi-uniform drift currents are deflected on the average by 40° to the right from the wind direction and they cover 60% of the circula- tion variance. Sea level variability is heavily (98%) dominated by nearly uniform changes which are caused by the water storage variations of the Gulf. Sea level gradients contain the main axis (23%) and transverse (17%) components, forced by winds of the same direc- tion. The flows below the surface are decomposed also into the main axis (24%–40%) and transverse (13%–16%) components that are correlated with the sea level gradients accord-ing to the geostrophic relations.
