An operational, global scale spectral ocean wave forecasting model

In late September 1985, the first global scale spectral ocean wave forecasting model designed to provide forecast guidance was placed in an experimental, operational mode at the National Meteorological Center (NMC) in Washington, D.C. The numerical model generates 72 hour forecasts of wave elevation directional frequency spectra in 360 components, and summary statistics at approximately 5000 sea grid points between S and N. Included within the coding of this particular model are physical simulations for three forms of spectral wave growth, overshoot, and directional band relaxation. Equivalent wind fields specified at a height of 19.5m above the sea surface are derived from 1000 mb and surface output fields of the NMC Medium Range Forecast atmospheric spectral model. Synoptic scale comparisons of northern and southern hemisphere wind fields with forecast significant wave height fields show good pattern agreements with the highest wave heights occurring under centers of action and over long fetches. Comparisons of forecast accuracy is expected to be obtained during the higher sea states of the upcoming northern hemisphere winter.