Multidecadal ensemble hindcast of wave fields in the Baltic Sea

Abstract

Several versions of the wave climate of the Baltic Sea are reconstructed by means of the spectral wave model WAM with a resolution about 3 nautical miles. This model (optionally covering different frequency range) is forced with two versions of wind fields and with and without the information about sea ice. We discuss the wave fields calculated for 1957-2008 (52 years) using high-resolution COSMO wind hindcast and for 1970-2007 (38 years) using slightly adjusted geostrophic wind fields from the Swedish Meteorological and Hydrological Institute database. The runs are performed in parallel with and without ice information. We provide a comparison of spatial distributions of the main climatological parameters (average wave heights, higher percentiles of wave heights etc., formal trends of these quantities) for these runs. All simulations replicate the well-known features of the Baltic Sea wave climate as the moderate average wave heights, extensive intermittency of wave properties and substantial spatial anisotropy of typical and extreme wave heights, with relatively severe wave climate in the eastern parts of the Baltic Proper and its sub-basins. The simulations also indicate widespread differences in the long-term behavior of average wave heights and higher percentiles of the wave heights in different sea areas.