The Black Sea Wave Energy: The Present State and the Twentieth century Changes

In this paper we present a study of the present state of the Black Sea wave energy. The studies of other authors are based on the use of input data from atmospheric reanalysis or a downscaling of such reanalysis. Instead of reanalysis data, we use input data from the operational limited area numerical weather prediction model ALADIN. We showed that the estimations of the Black Sea wave energy based on reanalyses deviate significantly from the real potential. We showed also that the highest values of the mean annual wave power flux is between 4.5 and 5.0 kW/m2 and the near shore areas with the highest wave energy potential are the southernmost Bulgarian coast and the coast of Turkey north of Istanbul. While we showed that the wind data from the reanalysis are not useful for the estimation of the actual wave energy potential, we claimed that the reanalysis data is useful to study the long term changes of the wave energy of the Black Sea. We used the 10m winds from the recent ERA-20C reanalysis, which covers the period 1901-2010. We performed a 110 years hindcast with these winds using the SWAN wave model. The results for the area with the highest mean annual wave energy showed that there was an increase during the first half of the XX century followed by a small decrease and again a period with elevated wave energy during the seventies. After 1980 there is a steady decrease of the Black Sea wave energy.