Annual and seasonal trend detection of significant wave height, energy period and wave power in the Mediterranean Sea

An analysis of a 40-year long wave time series was carried out in the Mediterranean basin to identify ongoing trends of three wave parameters: significant wave height, energy period and wave power. Synthetic wave data were deduced from the global atmospheric reanalysis ERA-Interim by the ECMWF. After a preliminary data examination, a trend analysis, at annual and seasonal scales, was performed on the mean and maximum values through the Mann-Kendall test. Moreover, the application of the Theil-Sen estimator allowed us to quantify the magnitude of the increase/decrease in the wave parameters. Results highlighted different behaviours between the mean and the maximum values. In general, an overall increase in the mean wave quantities was observed, particularly for the energy period, while the increase in the maximum wave parameters was limited to a few grid points. For both the mean and the maximum values, negative trends were identified in specific areas of the Mediterranean Sea, especially for the significant wave height and the wave power. The study findings could be useful for analyses linked to various activities such as coastal inundations and erosions, the design of marine structures and the identification of optimal sites for field installations of Wave Energy Converters.