Evaluation of the performance of a dynamic wave climate ensemble simulated using with EURO-CORDEX winds in the black sea and sea of azov

Abstract

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 (1979-2005). 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 RCM-forcings 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.