Otago academic helps forecast marine heatwaves

University of Otago marine science lecturer and Moana Project research supervisor Robert Smith...
University of Otago marine science lecturer and Moana Project research supervisor Robert Smith with a computer model of the Otago coastline and simulated particle sea surface temperatures. PHOTO: GERARD O’BRIEN
New Zealand’s first marine heatwave forecasts are being created with the help of a University of Otago marine science lecturer, with the aim of protecting the fishing and aquaculture industry from the severe impacts of rising sea surface temperatures.

As climate change affects our oceans, marine heatwaves are likely to become more common and intense in New Zealand waters, affecting ocean life and productive ocean industries.

As a New Zealand first, the Moana Project is using advanced ocean modelling to forecast when and where marine heatwaves are likely to occur.

University of Otago marine science lecturer and Moana Project research supervisor Robert Smith said the project focused on six coastal regions in New Zealand, and ocean surface temperatures were being forecasted a week ahead.

The forecasts were being made freely available to researchers, the public and industry.

Dr Smith said a marine heatwave was defined as ocean temperatures warmer than 90% of the temperatures experienced for that location and time of year for the past 25 years.

"Our models show past, present and future ocean temperatures.

"By comparing the forecasted temperatures to historical data, we can monitor and predict when and where the water is getting unseasonably warm.

"Although many New Zealanders don’t mind higher-than-normal ocean temperatures for the holiday season, there is a darker side to marine heatwaves.

"Warmer-than-normal temperatures may cause large-scale movement of fish stocks, they can lead to harmful algae blooms, and can stress or even kill valuable aquaculture species such as salmon and mussels.

"By forecasting marine heatwaves, we hope to provide warning to our important ocean industries and coastal communities."

The new forecasting tool can be accessed at moanaproject.org where a national forecast can be found as well as forecasts for Cape Reinga, Hauraki Gulf, Bay of Plenty, Chatham Islands, Cook Strait, Christchurch, Fiordland and Dunedin.

MetOcean Solutions lead scientist Joao Souza hoped that as the research continued, the seven-day forecast range could be extended.

"We are using observations and numerical models to better understand the causes, and increase the predictability of marine heatwaves around New Zealand.

"This will help us to forecast these extreme events with more certainty and give the public a warning," Dr Souza said.

"While the present tool gives us a short range forecast up to seven days, we are looking into ways to extend this to a few months using machine learning techniques."

The Moana Project is a five-year, $11.5million Ministry of Business, Innovation and Employment initiative.

It aims to improve understanding of coastal ocean circulation, connectivity and marine heatwaves to provide information that supports New Zealand’s seafood industry.



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