Cooler SST around western New Zealand, while an unusually warm SST anomaly lies east of the country

Coastal upwelling and a persistent SW airflow over New Zealand have led to Sea Surface Temperatures (SST) approximately 2 degrees Celsius lower than usual for this time of year around New Zealand’s West Coast (based on long term averages), while a large SST anomaly (with SST of +5°C above the average) to the east of New Zealand has begun to weaken as it slowly moves eastwards.

The SST anomaly data were obtained from NOAA satellites, and represents the difference between the daily SST and the long-term average. The resulting animation (see above) covers the period from 13th  December 2019 to 10th January 2020, and depicts a large blob of surface water +5°C above average persisting for about 16 days (13-28 December) before slowly dissipating as it tracks eastward. The large blob started to form in early December, as shown by the NOAA animation HERE.

Conversely, since the beginning of 2020, sea surface temperatures to the west of New Zealand have continued to cool in response to the persistent SW airflow over NZ.

“Understanding our marine environment and how it might respond to a changing climate is vital for safeguarding the sustainability of New Zealand’s blue economy, and is one of the key outcomes of the Moana Project; which aims to enable evidence-based decision making within environmental, social and economic applications.  These temperature fluctuations can threaten or place our kaimoana in a stressed condition, so understanding the changing temporal and spatial characteristics of the hydrodynamics around New Zealand, and particularly Marine HeatWaves (MHW) is important for understanding how different key kaimoana will react and adapt to changing environmental conditions,” says MetOcean Solutions General Manager Dr Brett Beamsley.

The Moana Project, embracing ‘the Internet of Things’ concept, has developed the Tiro Moana Sensor in partnership with Zebra-Tech. It is a plug and play auto offload profiling temperature sensor that can be deployed on commercial fishing gear in partnership with New Zealand’s seafood sector; the sensors are designed to transmit data in near real-time upon surfacing. These observations are intended to be assimilated into hydrodynamic models of NZ’s Exclusive Economic Zone increasing the accuracy of forecasts, including SST.

To know more about the Moana Project, visit https://www.moanaproject.org/ 

*Marine heatwave (MHW): a prolonged discrete anomalously warm water event that can be described by its duration, intensity, rate of evolution, and spatial extent. An anomalously warm event is considered to be a to be a MHW if it lasts for five or more days, with temperatures warmer than the 90th percentile based on a 30-year historical baseline period. From Hobday et al. (2016).