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This study evaluates the performance of a dynamic ensemble of wave climate simulations for the Black Sea. The ensemble members (and ensemble means) are evaluated for the historical period . The spectral wave model (simulating waves nearshore [SWAN]) was forced with eight Coupled Model Intercomparison Project Phase 5 (CMIP5) based Regional Climate Models (RCMs) wind fields to obtain each of the eight ensemble members. The RCMforcings used belongs to the European branch of the Coordinated Regional Downscaling Experiment (EURO-CORDEX). The ensemble members' historical wave climate is thoroughly compared against the ERA5 reanalysis, in situ observations, and altimeter measurements. In addition to the individual evaluation of ensemble members, the results for the 8-member ensemble mean are also examined. The performance of the ensemble members in reproducing the mean and extreme significant wave heights, mean wave periods, and mean wave directions is found to be good, with differences generally between +25 and −15% in comparison to ERA5. Differences between +10% and −30% were found for the comparison with altimeter measurements. We conclude that the ensemble better represents the wave climate of the Black Sea, than its individual members. The 8-member ensemble provides a more balanced dataset for the Black Sea wave climate and a better representation of the associated uncertainty. Thus, further wave climate projections for the Black Sea should rely on the use of an ensemble.

This study determines the qualities of atmospheric wind field data in comparison with wind measurements at five locations along the Black Sea coast. For this purpose, four different wind fields were obtained from three different weather centres (NCEP, NASA, and ECMWF). Three of these are reanalyses winds (Climate Forecast System Reanalysis CFSR, Modern-Era Retrospective-analysis for Research and Applications MERRA, ECMWF reanalyses ERA-Interim) and one is the operational dataset (ECMWF operational). The performance of them was determined using the wind measurements from 2000 to 2014 at five coastal locations along the southern coastline of the Black Sea (Kumköy, Amasra, Sinop, Giresun, Hopa) and from 2006 to 2009 at offshore location (Gloria) off the coast of Romania. Performances of these wind fields were determined based on statistical characteristics (mean, standard deviation and variation coefficient etc.), statistical error analysis for all data and for different wind speed intervals, wind roses and probability distributions. Besides, long-term variations of yearly error values (SI and bias) of wind speeds from wind data sources during 2000 - 2014 were discussed. Finally, it was concluded that the CFSR winds give the best performance at most stations. The ECMWF datasets yield better results along the western side but CFSR wind fields have shown better performance along the eastern side of the Black Sea coast and at Gloria offshore location.