Progress in Operational Wave Forecasting

Abstract Progress in operational sea stateforecasting is discussed in the context of the energy balanceequation. This fundamental law describes the evolution of the wave spectrum due to adiabatic processessuch as advection and refraction and due to physical processes such as generation of waves by wind, nonlinear interactions and wave dissipation. Progress in wave prediction is illustrated by means of a verification of operational wave height forecasts against wave height observations from buoysover the last 25 years of operational practice. Verification of modelled spectra against observed spectra by buoysis shown as well. At the moment a number of weather forecastingcentres spend a considerable amount of effort in the development of a fully comprehensive coupled atmosphere, ocean-wave, ocean circulation, sea-ice model. Central in the coupling of atmosphere and ocean in the ECMWF earth systemmodel (see e.g. [1]) are the ocean waves that determine the momentum and energy transfer across the sea surface. In this paper we therefore concentrate of the sea-statedependence of the momentum (and heat) fluxes by studying in some detail the wind input source functionof the energy balanceequation. The importance of the strong coupling between wind and waves is illustrated by means of impact studies.