Oceanum US East Coast ECMWF Wave Forecast

February 2025

Dataset description

The US East Coast wave forecast dataset provides operational wave predictions across the northeastern United States Atlantic seaboard, from Cape Hatteras to the Gulf of Maine (Figure 1). The domain encompasses the coastal waters of North Carolina, Virginia, Maryland, Delaware, New Jersey, New York, Connecticut, Rhode Island, Massachusetts, New Hampshire, and Maine. Wave forecasts are produced using the SWAN (Simulating WAves Nearshore) third-generation spectral wave model, with a 7-day forecast horizon updated every 12 hours (00, 12 UTC).

Wind forcing is provided by ECMWF IFS Open Data global atmospheric model. Spectral boundary conditions are supplied by the Oceanum Global WW3 wave model forced with ECMWF winds. Tidal currents are prescribed from Oceanum’s tidal constituents, enabling accurate representation of wave-current interactions in the Gulf Stream region and coastal embayments. Bathymetry is derived from the GEBCO 2023 global bathymetric grid.

The modelling setup employs the ST6 source term parameterisations. Spectra are discretised into 36 directional bins and 32 frequency bins, covering a frequency range from 0.037 to 0.71 Hz with 10% logarithmic increments. The model features a regular grid with a 5 km (0.05 degree) resolution, capturing the complex wave climate influenced by Atlantic hurricanes, nor’easters, and Gulf Stream interactions.

The dataset provides hourly forecast estimates for key ocean wave parameters (Table 2) including spectral quantities integrated over the full spectrum and for spectral partitions. Partitions are defined from an 8-second split (sea/swell) and from the Watershed method, which identifies one wind-forced partition and up to three swell partitions. Forecasts are archived for 30 days, and frequency-direction wave spectra are available at 1105 sites distributed across the domain. Nowcast datasets are also available, constructed by retaining the most recent data from each forecast cycle to provide a continuous near-real-time historical record.

Figure 1. Mean significant wave height from the US East Coast hindcast domain (used for forecast validation). The locations of 2D spectra hourly output are shown by the black dots.

Validation

The wave model physics and calibration have been validated against satellite altimeter observations for the corresponding hindcast domain. Validation results are available through the Oceanum Hindcast Satellite Validation App, which provides density scatter plots, quantile comparisons, and statistical metrics for the US East Coast region.

Data description

Table 1. Data description.

Linked Datamesh datasources

ECMWF-forced (12-hourly updates):

• Oceanum US East Coast ECMWF wave forecast parameters
• Oceanum US East Coast ECMWF wave forecast spectra

Nowcasts (continuous near-real-time archive):

• Oceanum US East Coast ECMWF wave nowcast parameters
• Oceanum US East Coast ECMWF wave nowcast spectra

Gridded output parameters

Integrated wave parameters are stored hourly over the domain at the native model resolution. Table 2 describes the gridded output parameters.

Table 2. Gridded output parameters.

Variable names link to the corresponding NERC Vocabulary Server standard name where available. All parameters are defined on the time, latitude and longitude coordinates.

Spectra output

Frequency-direction wave spectra are stored hourly at the spectra output sites within the domain. Table 3 describes the spectra output variables, using the exact variable names served by Datamesh.

Table 3. Spectra output variables.

Variable names link to the corresponding NERC Vocabulary Server standard name where available. Spectra are defined on the time, site, freq and dir coordinates; lon and lat are per-site data variables giving each site’s location.

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