Variability of currents over the southern slope of the Gulf of Finland

In our intraseasonal variability studies of currents in the coastal sea of the Gulf of Finland northeast of Pakri Peninsula, we compared the observation data from a bottom-mounted ADCP (March–June of 2009, 50 m depth) with the simulation data from High Resolution Operational Model of the Baltic (HIROMB). The structure of the current pattern appeared strongly dependent on the stratification conditions. The flow was quasi-barotropic during the periods of weak inverse thermal stratification at the end of winter season and at transition from the inverse thermal stratification to summer type stratification when the sea was thermally unstratified, but mostly two-layered (baroclinic) when the summer type thermal stratification had developed. The alternation of strong westward (eastward) currents (up to 30 cm s−1) in the upper layer is explained in terms of coastal upwelling (downwelling) due to favourable background winds. The measured and the modelled upper layers along isobath currents showed a noticeable correlation with the correlation coefficient of 0.52 and 0.82 during the periods of winter type and summer type stratifications, respectively, and the absence of a significant correlation during the transition period. The eastward (upwind) current episodes with speeds reaching 18 cm s−1 below the seasonal thermocline are likely to reflect the specific circulation response in the elongated basin caused by the easterly wind. The long-term mean (over 3.5 months) current vector (−2.0 cm s−1, −2.9 cm s−1) was westward in the upper sea and eastward, nearly along isobaths (1.1 cm s−1, −0.3 cm s−1) in the deeper layers

Characteristics of high-resolution sea ice dynamics in the Gulf of Finland, Baltic Sea

High-resolution Eulerian and Lagrangian sea ice kinematics are examined based on an ADCP and four icebound drifting buoys in the Gulf of Finland, Baltic Sea. The measurements were performed in the central Gulf of Finland in winter 2010 from January to March. Ice drift was mostly in near-free drift state driven by winds and ice-independent currents in the basin. Internal friction was significant, apart from off-ice forcing toward the open boundary. The averaged asymptotic ice/wind speed ratio and deviation angle at higher wind speeds were 0.034 and 9 degrees in the oceanic boundary layer, respectively. The ratio depended on the direction of the wind indicating the role of morphometry of the coast to the local ice kinematics. The maximum values of wind ratio were observed in cases of NE winds and minimum values in cases of SW winds. Coherent ice drift was observed up to a distance of 42 km.High-resolution Eulerian and Lagrangian sea ice kinematics are examined based on an ADCP and four icebound drifting buoys in the Gulf of Finland, Baltic Sea. The measurements were performed in the central Gulf of Finland in winter 2010 from January to March. Ice drift was mostly in near-free drift state driven by winds and ice-independent currents in the basin. Internal friction was significant, apart from off-ice forcing toward the open boundary. The averaged asymptotic ice/wind speed ratio and deviation angle at higher wind speeds were 0.034 and 9 degrees in the oceanic boundary layer, respectively. The ratio depended on the direction of the wind indicating the role of morphometry of the coast to the local ice kinematics. The maximum values of wind ratio were observed in cases of NE winds and minimum values in cases of SW winds. Coherent ice drift was observed up to a distance of 42 km.Peer reviewe

Development of a Deep Chlorophyll Maximum of Heterocapsa Triquetra Ehrenb. at the Entrance to the Gulf of Finland.

Abstract not availableJRC.H-Institute for environment and sustainability (Ispra