<![CDATA[CALYPSO SCIENCE

<![CDATA[CALYPSO SCIENCE - Blog]]>Tue, 14 Apr 2026 21:09:16 -0700Weebly<![CDATA[SeaScope Surf: A digital twin of Raglan for next-generation surf forecasting]]>Tue, 14 Apr 2026 01:42:33 GMThttps://www.calypso.science/blog/seascope-surf-a-digital-twin-of-raglan-for-next-generation-surf-forecastingAhead 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.

]]><![CDATA[Lyall bay (NZ) circulation and implications on water quality]]>Tue, 10 Mar 2026 02:34:20 GMThttps://www.calypso.science/blog/lyall-bay-nz-circulation-and-implications-on-water-qualityAs outlined in a previous post, we implemented a high-resolution hydrodynamic domain to drive dispersion modelling of the untreated wastewater continuing to be discharged from the long outfall at Moa Point, Wellington. This also provides useful insights into the circulation within Lyall Bay and implications for water quality.

Lyall Bay can be thought of as two connected systems; the inner Bay, with a mostly clockwise flow regime, and the outer Bay which typically has a counter clockwise circulation pattern. See Figure 1 for the main flow patterns.

Figure 1. The red cross indicates the outfall location.

During low wave conditions, the inner Lyall Bay water remains quite isolated from the outer Bay and the adjacent coastal circulation and its strong tidal flows. This amount of disconnection has two important effects from a water quality perspective. While untreated sewage from the offshore outfall has no direct path to the inner Bay, any sewage that does enter the inner Bay (for example due to previous weather conditions) is not readily flushed out. See Figure 2 for a typical low wave flow map.

Figure 2.

During high waves and southerly wind conditions, a very different picture emerges - particularly during the outgoing tide stage. Here, sewage discharge from the outfall connects with a strong onshore directed flow along the west side of the outer Bay, directing sewage toward the inner Bay and the shoreline. During these southerly storms the inner Bay has a distinct clockwise circulation pattern, which means the sewage is distributed all along the beach and only slowly disperses out to the adjacent coast. See Figure 3.

Figure 3.

During energetic waves events, onshore Stokes drift will further enhance the potential for pollutant connection with Lyall Bay and should be included in dispersion simulations (Figure 4). Our modelling has also shown it can lead to an underestimation of intrusion within the harbour if omitted.

Figure 4.

Overall, this is not a straightforward process — the configuration of these circulation cells is strongly modulated by the interplay of tidal stage, wind, wave energy, and wave incidence. A high-resolution model is therefore valuable to reliably drive the dispersion modelling.

These insights can be applied operationally to help time outfall shutdowns or flow reductions during periods when connection with Lyall Bay is most likely.

We hope these tools serve as a valuable resource for identifying and planning around expected pollution peaks while the issue remains unresolved.

]]><![CDATA[Monitoring Sewage Pollution along the Wellington Coast]]>Wed, 04 Feb 2026 23:39:37 GMThttps://www.calypso.science/blog/monitoring-sewage-pollution-along-the-wellington-coastPollution in coastal waters is a growing concern, affecting marine ecosystems, fisheries, and local communities. To better understand the current conditions in Wellington Harbour, we have developed an interactive map showing the distribution and movement of pollutants in near-real-time.

The map is based on hydrodynamic simulations using our 3D SCHISM model, which accounts for tides, currents, and water mixing, combined with a Lagrangian model that tracks water masses over time.

Using the slider below, you can explore the spread of the wastewater plume at different times of the day. Click on the map to view a timeseries for a specific location. The values range from 0 to 1, where 1 represents the maximum concentration at the pipe, and 0.5 indicates the plume has been diluted by half.

Using this tool, residents, researchers, and decision-makers can:

Track the movement of pollutants hour by hour
Identify areas of high concentration and potential environmental impact
Support planning for mitigation or monitoring activities

Below, you can explore the map interactively. Use the time slider to move through the day and see how pollutant levels change across the harbour.

About the Data
Our model is updated daily using data from the Oceanum Datamesh platform. The map shows surface pollution concentrations. The app can access directly here www.seascope.io

]]><![CDATA[Operational National-Scale 3D Hydrodynamic Forecasting for New Zealand Using SCHISM]]>Wed, 28 Jan 2026 19:27:31 GMThttps://www.calypso.science/blog/operational-national-scale-3d-hydrodynamic-forecasting-for-new-zealand-using-schismOver the past years, Calypso Science has been developing high-resolution hydrodynamic representations of New Zealand’s coastal and shelf waters. Early work focused on a national hindcast, which provided a 3D baroclinic reconstruction of currents, temperature, salinity, and tides across the country (National data cube). Building on that work, thanks to PredictWind, we have now deployed a fully operational, national-scale forecast using SCHISM, capable of delivering hourly 3D fields of velocity, temperature, and salinity across the entire New Zealand domain.

The operational SCHISM model is defined on an unstructured horizontal grid, with high resolution in narrow sounds and channels while maintaining coarser resolution offshore, providing the necessary flexibility to capture fine-scale coastal processes without prohibitive computational cost. Vertically, the model employs a LSC grid, allowing detailed representation of stratification and baroclinic processes, critical for reproducing thermoclines, density-driven currents, and tidal interactions. Tidal forcing is included through a comprehensive set of harmonic constituents, including M2, S2, N2, K2, K1, O1, P1, Q1, MM, MF, M4, MN4, MS4 and 2N2 components, applied at the open boundaries to reproduce both elevations and tidal currents across the domain.

Daily GLORYS Copernicus analysis of 3D temperature, salinity, and velocity fields are provided at the open boundaries, while atmospheric forcing from the GFS 0.25° forecast supplies surface wind stress, solar radiation,and atmospheric pressure. Within the model, nudging is applied for temperature and salinity near the boundaries to maintain consistency with global forecast, with carefully chosen distances and strengths to avoid abrupt gradients.

Once computed, the hourly outputs are integrated into SeaScope, where users can explore temperature fields in direct comparison with real-time drifters, moorings, and coastal profilers, as well as GLORYS analysis. This allows operational forecasts to be interpreted in the context of ongoing observations, providing both validation and a consistent view of New Zealand’s complex coastal and offshore environment.

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