Oceanum Western Europe ERA5 Wave Hindcast

February 2025

Dataset description

The Western Europe wave hindcast dataset provides a detailed account of ocean wave parameters across the waters of northwestern Europe (Figure 1). The domain encompasses the North Sea, Irish Sea, Celtic Sea, English Channel, and the northeastern Atlantic waters off the coasts of Ireland, the United Kingdom, France, Belgium, the Netherlands, Germany, Denmark, and Norway. This region experiences a complex wave climate influenced by Atlantic swell, extratropical cyclones, and the interaction between open ocean and semi-enclosed seas. Wave spectra are computed over a 45+ year period between 1979 and present using the SWAN (Simulating WAves Nearshore) third-generation spectral wave model. The model is driven by inputs from the Oceanum Global Wave Model for spectral boundaries and ERA5 reanalysis winds from the European Centre for Medium-Range Weather Forecasts. Bathymetry is derived from the GEBCO 2020 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 multi-resolution grid system:

• Western Europe 5 km: Parent domain covering the entire region at 0.05 degree resolution
• Dutch Coast 1 km: High-resolution nest covering the Dutch North Sea coast at 0.01 degree resolution

The dataset provides hourly (Dutch Coast) and 3-hourly (Western Europe) estimates for an extensive array of 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. These data are stored over the entire grid at native resolution. Additionally, frequency-direction wave spectra are available at 16613 sites (5km domain) plus 456 sites (Dutch Coast) distributed across the domain (see Figure 1).

Figure 1. Mean significant wave height from the Western Europe hindcast domain. The locations of 2D spectra output are shown by the dots (black for 5km domain, blue for Dutch Coast nest). The blue box indicates the Dutch Coast 1km nest extent. Depth contours are shown at 50m, 100m, 200m, 500m, 1000m, and 2000m.

Validation

The wave hindcast can be validated against satellite altimeter observations using the Oceanum Hindcast Satellite Validation App. This interactive tool allows users to compare modelled significant wave height against satellite altimeter measurements at any location within the model domain, providing density scatter plots, quantile comparisons, and statistical metrics.

Data description

Table 1. Data description.

Linked Datamesh datasources

Western Europe 5 km

• Oceanum Western Europe 5 km 3-hourly wave parameters
• Oceanum Western Europe 5 km 3-hourly wave spectra
• Oceanum Western Europe 5 km gridded wave statistics

Dutch Coast 1 km

• Oceanum Dutch Coast 1 km hourly wave parameters
• Oceanum Dutch Coast 1 km hourly wave spectra
• Oceanum Dutch Coast 1 km gridded wave statistics

Integrated parameters gridded output

Integrated wave parameters are stored 3-hourly over the domain at the native model resolution. Table 2 describes long names and units of the 39 gridded output parameters, including one wind-forced partition and three swell partitions from the Watershed method.

Table 2. Gridded output parameters.

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