Numerical Ocean Wave Prediction for European coasts (EWAM)

The basis of the Numerical Ocean Wave Prediction of the Deutscher Wetterdienst (DWD) is a 3rd generation spectral wave model (3G-WAveModel). Spectral models describe the sea state in terms of the 2-dimensional distribution of wave energy by frequency (or period or wave number) and propagation direction. In the current version, a resolution of 36 directions and 30 frequencies (wave periods between 1.5 and 24 seconds) is used. In the numerical model, the temporal evolution of the wave energy spectrum is calculated at a multi-tude of points of a grid stretched over the sea surface. The wave energy changes through the following physical processes: • Wave growth due to the downward momentum flux from the wind field • Wave propagation (advection, refraction) • Redistribution of energy between wavenumbers due to nonlinear interactions • Dissipation (internal friction and wave breaking) Similar to the chain of atmospheric models (ICON, ICON-EU and ICON-D2), the wave prediction system serves more than one forecast areas: the global model GWAM, the European model EWAM and the high-resolution coastal model CWAM. In the model, wave growth is forced by analyzed and predicted 10m winds of the atmospheric models.