Variations in wind velocity components and average air flow properties at Estonian coastal stations in 1966–2021; Sõrve Peninsula case study

Abstract

Despite considerable differences in local conditions, the average air flow parameters at coastal stations had similar seasonal and interannual patterns. The decreasing trends in average wind speeds were not reliable due to inhomogeneity in the long-term series. Being less sensitive to inhomogeneities, both the zonal and meridional components and the average air flow estimates increased in 1966–2021. The changes in flow direction and in other wind characteristics were better described as quasi-cyclic rather than using a linear trend. In the Sõrve coastal case study, the wind velocity components were separated into opposite subsets, which were one-sidedly analysed by ignoring the other direction. Both westerly and easterly sub-components increased by 0.5 m/s in 2004–2021. Regarding wind-driven coastal processes along the peninsula, the changes in the westerly component, but not in the easterly component, are important on the western coast, and vice versa for the eastern coast. Assuming the potential impacts of winds via waves and currents, the influence of long-term changes in sea ice conditions were considered. Although the forcing load was more than twice as high on the western coast, the relative effect of the ‘ice mask’ was smaller, as ice conditions were milder there. Along the eastern coast of the Sõrve Peninsula, the prevalence of SW-directed forcing can be expected, because the westerly forcing is shaded there by land. The SW-directed flow has strengthened over the study period because of an increase in the easterly and northerly wind speed subset and a decrease in the ice cover on the Gulf of Riga.

Keywords

• wind climate
• air flow
• sea ice
• wind energy
• coastal processes
• baltic sea