28 Year Bay of Plenty Hindcast completed

Left: Bay of Plenty high resolution model showing current speeds. Right: PhD student Mireya Montaño.

Moana Project PhD student Mireya Montaño has successfully completed a 28 year hydrodynamic hindcast model (1993-2020) of the Bay of Plenty, Te Moana-a-Toi. This is a regional zoom-in model providing a higher resolution view (one kilometer square) for the Bay of Plenty. This zoom in includes a realistic coastline as well as bathymetry (sea floor) data providing a detailed depiction of the Bay of Plenty.

Hindcasts are used to reconstruct historical events. Much like a weather forecast can tell you about the future, a hindcast looks back in time. They allow the user to look at how specific factors have changed over time; for example, we know sea temperatures are rising and with the hindcast we can look closely at those changes over the past 28 years.

The Bay of Plenty model helps the He Hono Moana team of the Moana Project. Paired with OpenDrift (a particle tracking software) the model is used to track mussel larvae, one of the taonga kaimoana species being investigated in the Moana Project.

“The farm uses spat (baby mussels) collected on ropes from the local environment. This means they are interested in knowing where the spat comes from,” Mireya says of the experiment. “We are able give the particles similar characteristics to mussel larvae where they float in the water for a minimum of 21 days and a maximum of 35. Mussel larvae only settle on certain habitat types and if the particles are not settled in their ideal habitats by day 35, they die off. If they do settle then we can estimate where they will be.”

With the whole 28 years hindcast complete, Mireya’s next goal is to conduct experiments with the model and create environmental maps. These will look into patterns of the ocean circulation, and temperature changes throughout the seasons.

And when she’s not investigating the ocean, Mireya is enjoying it. Currently based in Raglan, Mireya is an active swimmer and surfer – opting to go for a paddle most days when the weather is fine.

“I moved from Dunedin to Raglan and it was a big change weather-wise, the weather makes a difference to your day. My hometown of Tijuana has that classic sunny Californian weather you see in movies so I really learnt a new definition of cold when I was in Dunedin. But Raglan is slightly closer to what i’m used to at home!”