MetOcean Solutions Ltd has been supplying regular spill trajectory forecasts for the Rena incident.

Rena, a Liberia-flagged 235m vessel ran aground at Astrolabe Reef, off the Bay of Plenty, New Zealand shoreline at approximately 2.20 am on the 5th of October, 2011. Heavy fuel oil was seen to be leaking from the vessel on Wednesday morning. Following the initial release of oil it was observed that ongoing releases occurred on each low tide.

Maritime New Zealand maintains and operates an oil spill trajectory model. To complement those predictions, the MetOcean Solutions trajectory system has been used as an independent source of information, based on the use of MetOcean’s local-scale high-resolution wind, wave and current forecast data.

MetOcean run operational forecasts with a New Zealand scale atmospheric model (WRF) plus a regional current (POM) and wave (SWAN) model. Forecast cycles are run every 6 hours with predictions for up to 7-days in advance. Data include the tidal and residual currents all around NZ.

The forecast system updates automatically every 6 hours, and these high-resolution data are being used in the General NOAA Operational Modelling Environment (GNOME), which predicts the fate of the spilled oil.

To account for the variability of time release of the spill, GNOME has been setup to release oil 2-hours either side on low tide only. In the attached simulation, the black particles represent the expected plume while the red particles represent a “minimum regret” or worst case spreading of the plume.

The first oil arrived on Mt Maunganui Beach in the morning of 10th October, and by midday there were long lines of stranded oil. Later that evening there were reports of oil reaching as far south as Papamoa.

Initial feedback from onsite responders suggest that the predicted timing and location for the beaching of the plume was accurate.

For more information on MSL emergency response interface (ERI), contact us at +64 6 758 5035 or email: enquiries@metocean.co.nz.