Forecasting Marine Heatwaves

The Project: Marine heatwaves in the Indo-Pacific region, their predictability and social-economic impacts

Our project team is working to improve the skill (accuracy) and leadtime (out to six months) for forecasts of extreme temperature events around Australia, using advanced machine learning statistical methods. This project will run from 2020-2022.

How we make these forecasts: We use machine learning to detect features in the distribution of sea surface temperature and upper ocean heat content which are most predictive of future marine heatwave events. We have built on approaches developed by Ham et al (2019). The machine learning model has been trained on CMIP5 and CMIP6 climate model runs and validated on the GODAS (Global Ocean Data Assimilation System) data set. After conditioning with a training dataset, the machine learning model is then used as a simulator to predict marine heatwave events in the focal region a few months ahead, depending on the regional skill of the forecast system. We are testing the system in two regions of Australia, known to be global warming hotspots (Hobday and Pecl 2014), (1) off Western Australia, and (2) Tasman Sea in South-east Australia.

THESE FORECASTS ARE EXPERIMENTAL PRODUCTS ONLY AND INTENDED FOR RESEARCH PURPOSES

Forecast region – Western Australia

Our first forecast was created in December 2020, and was based on historical data up to November 30, 2020.

WARNING: THERE IS A HIGH LIKELIHOOD OF MARINE HEATWAVE DEVELOPMENT BETWEEN JANUARY AND APRIL 2021

Average February sea surface temperature for the period 1982-2020. The forecast region is shown in the red box

West Australia MHW forecast

Forecast region – Tasman Sea, south-east Australia

Our first forecast was created in January 2020, and was based on historical data up to November 30, 2020

NO WARNING: THERE IS A LOW LIKELIHOOD OF MARINE HEATWAVE DEVELOPMENT BETWEEN JANUARY AND APRIL 2021

Average February sea surface temperature for the period 1982-2020. The forecast region is shown in the red box

How did these predictions pan out?

We can follow in real time the development of marine heatwaves using satellite observations available on the Marine Heatwave Tracker.

Forecast region – Western Australia

By early January 2021, a MODERATE-STRONG marine heatwave had formed in the area we forecast based on information to November 2020. The left panel below shows the spatial extent of the heatwave on January 12, and the image on the right shows the time series of temperature for a location off Geraldton. The black line is the observed temperature from satellite, the blue dashed line is the average expected, and the red dotted line is the threshold temperature for a heatwave. The coloured area shows the time that the marine heatwave began. It has intensified from MODERATE to STRONG in this location.

Forecast region – Tasman Sea, south-east Australia

No marine heatwaves detected to Feb 10, 2021 in the forecast region (41 S, 150 E). Data from www.marineheatwaves.org/tracker

Project Team

  • Alistair Hobday (Project lead)
  • Fabio Boschetti (Forecasting)
  • Ming Feng (Oceanography)
  • Jason Hartog (Heatwaves)
  • Xuebin Zhang (Climate models)

Project Publications and Presentations

  • AMOS Feb 2021 (virtual presentation) Boschetti et al. Statistical prediction of marine heatwaves via machine learning.
  • Marin, M., M. Feng, H. E. Phillips and N. L. Bindoff (2021). A Global, Multiproduct Analysis of Coastal Marine Heatwaves: Distribution, Characteristics, and Long-Term Trends. Journal of Geophysical Research: Oceans 126: e2020JC016708. https://doi.org/016710.011029/012020JC016708.

Media links

  • WA facing marine heatwave in early 2021. The Guardian Dec 24, 2020.
  • Marine heatwave emerges as predicted in Western Australia. The Midwest Times Jan 20, 2021
  • WA coast caught in what’s believed to be the most prolonged marine heatwave in a decade. ABC Feb 21, 2021

References

  • Ham, Y.-G., J.-H. Kim and J.-J. Luo (2019). Deep learning for multi-year ENSO forecasts. Nature: https://doi.org/10.1038/s41586-41019-41559-41587.
  • Hobday, A. J. and G. T. Pecl (2014). Identification of global marine hotspots: sentinels for change and vanguards for adaptation action. Reviews in Fish Biology and Fisheries 24: 415-425. DOI 410.1007/s11160-11013-19326-11166.