Symmetric influence of forward and opposing tidal currents on rogue wave statistics

Abstract

Rogue waves are associated with various ocean processes, both at the coast and in the open ocean. In either zone, inhomogeneities in the wave field caused by shoaling, crossing seas or current interactions disturb the wave statistics, increasing the rogue wave probability and magnitude. Such amplification of the frequency of rogue waves and their intensity, i.e. the maximum normalised height, have been attested to in numerical simulations and laboratory studies, in particular for wave–current interactions. In this study, we investigate the effect of the current intensity and direction on rogue wave probability, by analysing long-term observations from the southern North Sea. We observe that the amplification is similar for opposing and following currents. Despite the sea states being dominantly broadbanded and featuring a large directional spread, the anomalous statistics are of the same order of magnitude as those observed in unidirectional laboratory experiments for stationary currents.