Submesoscale dispersion of surface drifters in a coastal sea near offshore wind farms

Abstract

Abstract. We analysed relative dispersion of surface drifters released as pairs (six instances) or triplets (two instances) during three field experiments conducted in the German Bight in close proximity to wind farms. There is some tentative evidence that nearly exponential growth of relative dispersion (non-local dispersion) preferably occurs for drifter pairs that are most exposed to the influence of a wind farm. Kinetic energy spectra and velocity structure functions are analysed with regard to the assumption that turbulent energy could be injected by tides, possibly also via an interaction between tidal currents and wind turbine towers. Applicability of inertial range turbulence theory, however, can be doubted given distinct peaks of overtides observed in velocity power spectra. More comprehensive studies would be needed to better separate submesoscale effects of wind farms, tides and possibly baroclinic instabilities on observed drifter behaviour in a complex coastal environment.