SeaScope Surf: A digital twin of Raglan for next-generation surf forecasting

Ahead of the World Surf League (WSL) event in Raglan, a new operational platform has been launched: SeaScope Surf. The system provides a high-resolution digital twin of the Raglan coastal domain, designed specifically for surf forecasting, operational oceanography, and coastal decision support.
The platform integrates real-time observations, multi-source numerical modelling, and statistical wave diagnostics to deliver a unified representation of surf conditions across all major Raglan breaks, including Manu Bay, Whale Bay, Indicators, and Ngarunui Beach.

The system is built on a fully coupled modelling framework implemented within the Oceanum infrastructure. At its core, a SCHISM hydrodynamic model resolves the tidal dynamics, coastal circulation, and wave–current interactions within the embayment at high spatial resolution. This hydrodynamic component is dynamically coupled with a WWM wave model, allowing for explicit feedback between evolving wave fields and ambient currents. This coupling is essential in a site such as Raglan, where tidal modulation and bathymetric steering strongly influence breaking wave characteristics at multiple point breaks.

Boundary conditions are supplied through a nested configuration that ensures consistency across scales. Offshore wave conditions are provided by an Oceanum wave model, which propagates swell systems generated across the South Pacific into the regional domain. Atmospheric forcing is derived from a combination of high-resolution PredictWind fields and ECMWF products, ensuring that both local wind variability and synoptic-scale atmospheric structures are accurately represented. At the ocean boundaries, Copernicus Marine Service datasets provide consistent large-scale sea level and circulation constraints, maintaining physical realism in the open boundary forcing.

The modelling system is executed in a daily operational cycle, in which a fully coupled SCHISM–WWM simulation is run once per day. Particular attention is given to the interaction between swell propagation, tidal elevation changes, and nearshore bathymetry, which together control wave breaking patterns across the different Raglan surf breaks.

A key feature of SeaScope Surf is the extraction of directional wave spectra at discrete surf locations. Instead of relying solely on bulk parameters such as significant wave height or peak period, the system provides full frequency–direction spectra at each break. This allows a much more detailed understanding of wave energy distribution, including the presence of multiple swell systems and their evolution through the coastal zone. From these spectra, additional derived parameters are computed, including swell partitioning and local transformation indices that describe how offshore wave energy is redistributed by refraction, shoaling, and breaking processes.

In addition to wave modelling, the system integrates observational data from tidal gauges provided by WRC. These instruments deliver water level measurements at one-minute resolution, which are used both for real-time validation and for spectral analysis of sea level variability. The comparison between modelled and observed sea levels provides an important constraint on the hydrodynamic performance of the SCHISM component.

A key output derived from the tide gauge is a practical new surf metric: the Set Rhythm. Computed from spectral analysis of the water level over the previous hour, it quantifies the number of wave groups arriving per hour together with their relative intensity, providing a simple and robust descriptor of daily surf conditions based directly on in-situ observations. It also enables comparison with previous days : is today more, less, or similarly 'setty' than the yesterday ? What makes this particularly valuable is that it comes directly from in-situ measurements at the boat ramp itself, not from a model — making it a ground-truth indicator of the real-time conditions.

Overall, SeaScope Surf represents a fully integrated digital ocean system for the Raglan region. By combining advanced numerical modelling, multi-source forcing datasets, and high-frequency observational data, it delivers a consistent and operationally relevant description of coastal dynamics. The result is a platform that not only predicts wave conditions, but also translates complex ocean physics into actionable surf intelligence at the scale of individual breaks.