Coastal trapped waves in the northwestern Mediterranean

This paper presents a study of coastal trapped waves on the continental margin of the northwestern Mediterranean. Cyclonically propagating waves along the coast were determined by cross-correlating alongshore current and sea level time series measured at different locations. Significant correlations between alongshore current time series were obtained at different time lags corresponding to the first three coastal trapped waves (CTW) modes. However, correlations between sea level time series were just found for the first CTW mode. The wind-forced coastal trapped theory (with bottom friction and scattering) was applied to the region and model output was compared with data. This application used five coastal sections, a summer or winter stratification, and winds from five coastal sites. The model was able to successfully reproduce observed alongshore current fluctuations in the Catalan Sea. The impact of stratification on CTW was proposed as the mechanism which reduces the effect of the complex topography on low-frequency alongshore flow.