Towards quantifying variations in wind parameters across the Gulf of Finland

Several features of the spatial structure of wind patterns over the Gulf of Finland in the NE part of the Baltic Sea are analysed on the basis of wind parameters measured at two lighthouses (Tallinnamadal near the southern coast of the gulf and Kalbådagrund near its northern coast), which are compared with the High Resolution Limited Area Model (HIRLAM) 6.4.0 outputs for the period of April 2007–March 2008. It is shown that both the average air flow and the wind direction turn considerably clockwise when the air masses cross the gulf obliquely. Consequently, the influence of the Estonian mainland on the wind properties over the Gulf of Finland extends at least to a distance of 20 km to the Tallinnamadal Lighthouse area but hardly reaches a distance of 60 km where Kalbådagrund is located. The HIRLAM model captures well the wind direction at Tallinna­madal, whereas at Kalbådagrund the modelled wind direction is turned by > 20° counter-clockwise from the measured direction. The HIRLAM output matches well the wind speed at Kalbådagrund, but underestimates it at Tallinnamadal by more than 1 m/s.