Objectives of the service
Saving fuel is key to reducing operating expenses in the shipping industry and meeting increasing regulatory requirements for greenhouse gas emission reductions.
A recent feasibility study made for ESA has shown that significant fuel savings can be achieved by integrating the best ocean circulation models with satellite data. The DHI Global Seas project has implemented findings from this feasibility study into a fully operational, cloud based global forecast system.
The extension of the DHI Global Seas project, DHI Global Seas Offshore Wind Energy CCN (Contract Change Notice) is focussing on the offshore wind industry. Reducing downtime when constructing and when servicing offshore wind farms is an important factor in lowering costs of this renewable energy resource. To achieve this, highly accurate wave forecasts with uncertainty assessment is required, which is added to the original service in this second part of Global Seas.
Together the two parts of DHI Global Seas provides global forecasts of winds, waves, currents and water levels where satellite data are assimilated into the wave and current models. Furthermore, the accuracy of the models can be checked by the users through a comparison with measurements and satellite data. The users are not restricted to the shipping industry and the offshore wind industry only, but includes all users working at sea.
Users and their needs
The users addressed by the DHI Global Seas service, and their needs are:
Shipping companies: Reduce operating expenses through fuel savings, better fleet management and lower risks
Software and service providers (to the shipping companies): Provide performance assessment and routing service that can lead to fuel savings and lower risks
The users addressed by the DHI Global Seas Offshore Wind Energy CCN service, and their needs are:
Contractors: Designing, planning and executing transport and installation of offshore wind turbines and their substructures as well as associated substations
Wind Farm Operators: Managing service, maintenance and repair activities of Offshore Wind Farms during operation
Service Providers to 1. and 2.
Service/ system concept
The DHI Global Seas and DHI Global Seas Offshore Wind Energy CCN data is provided from a large set of accurate regional ocean current models enriched through assimilation of satellite altimetry data combined with global wind, wave, oceanographic and tidal models also based on satellite altimetry.
DHI Global Seas and DHI Global Seas Offshore Wind Energy CCN delivers hourly information on ocean current, wave and wind forecasts up to five or 10 days ahead in time globally.
Additionally, users themselves can compare wave and currents model results as we have included a transparent comparison of model skill to the main global metocean data sets currently being used by the industry, and we operationally predict an estimate of the space and time varying accuracy to be expected from our wave and current models.
The data flow for the current forecasts are illustrated in the figure below, where regional current models are forced with data from the global Copernicus model, satellite data are assimilated into the models, and forecasts delivered to the users through e.g. an API.
The data flow for the wave model is a bit simpler as DHI Global Seas Offshore Wind Energy CCN includes a global wave forecast model itself thus not requiring an external global wave model. The forecasts are delivered in a similar way as the current forecasts.
Space Added Value
This solution relies most heavily on altimetry-based sea surface height, significant wave height and wind speed products and scatterometer wind speed data. Sea surface observations are both used for continually updating the tidal water level and current products and it is the most important satellite observation for constraining mesoscale dynamics (most noticeably ocean eddies and western intensification currents like the Kuroshio and the Gulf Stream) in ocean models via data assimilation.
For the wave predictions, the combination of altimetry, scatterometry and in situ will particularly impact swell prediction, which are often critical to predict for offshore wind operations.
The regional ocean current prediction approach from Global Seas already incorporates altimetry data products from e.g., the SRAL instrument on Cryosat-2, Jason 1-3 and Sentinel 3A and 3B. With the newly released data products from Sentinel-6 (Michael Freilich) there is scope to quite significantly increase the data availability for the Global Seas solution, which again should lead to higher accuracies and confidence in the Global Seas modelled parameters when the Sentinel-6 data is incorporated into the solution. In the Global Seas CCN we will therefore extend the current data processing system to also include the Sentinel-6 data in near-real-time and assess and, if possible, optimize the data accuracies.
To further improve the model skills on particularly wave predictions, the Global Seas EO database will also be extended by integration of scatterometer surface wind speed data. The following additional data products will be added to the satellite database made available for the Global Seas service:
While the DHI Global Seas has been finalised the DHI Global Seas Offshore Wind Energy CCN is ongoing and has successfully conducted user-interviews and co-creation events with seven end-users representing both contractors, wind farm operators and service providers.
Based on this workshop the user needs, user requirements and system requirements have been identified. These are being used in the further work with the design of the service.