The persistence of spatial patterns of beaching of current-driven pollution in a changing wind climate: a case study for the Gulf of Finland

We analyse long-term properties of current-driven transport of various items and substances to the nearshore from the vicinity of a fairway in the Gulf of Finland under the changing wind climate. The transport is replicated using semi-Lagrangian trajectories of parcels located at the sea surface. The trajectories are reconstructed with the TRACMASS model from surface velocity fields simulated by the Rossby Centre Ocean model for 1965–2004. The proportion of hits to the southern and northern nearshore varies in single years, but their long-term chances for being hit are equal. The number of hits to single nearshore sections greatly varies along the shore and in different years. The 5-year average spatial pattern of hits is highly persistent both qualitatively and quantitatively. Although the patterns of surface currents may have reacted to changes in the wind climate, the frequency and spatial patterns of beaching of current-driven pollution have remained unchanged over almost half century.