Using today’s ocean observations to unlock tomorrow’s climate

By Dr Thomas Moore, Sophie SchmidtJune 5th, 2020

As Australia comes to grips with the devastating COVID-19 global pandemic, it’s possible to forget that only six months ago much of the nation was in the grips of an unrelenting 2019–20 bushfire season. The “Black Summer” wrought tragic loss of life and property and environmental destruction across much of south-east Australia.

With Australia effectively ‘locked in’ to more extreme events as a result of global warming, research underway at the CSIRO Climate Science Centre by Dr Bernadette Sloyan and her ocean observations team is helping us track and trace the links between today’s ocean and tomorrow’s climate.

Dr Bernadette Sloyan, a Chief Research Scientist with CSIRO’s Oceans and Atmosphere and leader of the IMOS Deep Water Mooring facility, scans the horizon for the first signs of a deep-water mooring that has been released from its anchor out in the Coral Sea off Brisbane. (Photo: Dr Thomas Moore/CSIRO)

Ocean memory sets the future

Australia’s interconnecting oceans (the Southern Ocean, Indian Ocean and the Pacific), together with the atmosphere play a primary role in determining our climate system – with repercussions for our communities, industries and ecosystems.

Out beyond the beaches that gird our shores are large masses of ocean that store up heat from the atmosphere. As these masses move around the world they release this heat influencing our climate patterns year to year.

“The state of today’s ocean has a direct influence on monthly and longer-term climatic conditions and that in turn sets the stage for the future extreme events Australia will be facing,” says Bernadette.

“In order to get a better understanding of climate impacts like floods, droughts and heatwaves, we need to gain a long-term, uninterrupted, and complete picture of ocean properties and dynamics.”

Getting the complete climate picture

Dr Sloyan works closely with Australia’s national facilities, the Integrated Marine Observing System (IMOS) and the 94-metre world-class ocean research vessel RV Investigator. She leads Australia’s at-sea observation program of both the Indonesian Throughflow (ITF), identifying the exchange between the Pacific and Indian Oceans, as well as the East Australian Current (EAC), where a mooring array is currently keeping an eye on this western boundary of the South Pacific.

Track of the RV Investigator for Dr Sloyan’s 2019 voyage, supporting the IMOS deep-water mooring array and exploring the dynamics of the East Australian Current. (Map: CSIRO/MNF)

There’s currently no ‘silver bullet’ observations solution – a single piece of technology that would hypothetically allow researchers to get a complete view of these regions. Part of the work of Sloyan and her team is doing is to intricately link different observation technologies across land and sea to get the full picture of the climate state. On the ground, there’s 7,000 Bureau of Meteorology national weather stations that monitor Australia’s atmosphere. Then there is specialist observation infrastructure like the CSIRO and Bureau of Meteorology jointly-operated Cape Grim Baseline Atmospheric Monitoring station.

However, sea observations – of what is essentially “ocean weather” – is a far bigger logistical challenge. Australian-led observations, combining Argo floats, moorings, research vessels and other technologies, are part of an international effort to provide a global view of oceans, and are revolutionising ocean observing systems. But they are inherently time and labour intensive. RV Investigator offers a ‘turn-key solution for research’ that is allowing the team to meet this challenge head-on – reaching to the far west, east and south of our ocean domain.

Real-world data providing critical insights

In the last decade or so, satellite technology has become an increasingly popular tool for oceanographers to gather timely observations. Yet, for the ocean, remote sensing from space mostly tells us about the top layer of the sea, like sea surface temperature (SST). To determine how much heat is stored in the global ocean we need to look deeper.

One of the ways Dr Sloyan and her team are filling these critical knowledge gaps is by undertaking regular voyages aboard RV Investigator to the East Australian Current (EAC) every 18 months. It is here that the team has deployed an impressive array of six deep-water moorings for IMOS that monitor this important current.

Standing 5 kilometers tall on the seabed off the coast of Brisbane, sensors strung up and down the EAC moorings keep a record of the marine environment, measuring the ocean’s circulation and heat along with freshwater movements that are linked to our weather at the coast and inland.

Blue-water deck work is a unique and critical capability of CSIRO’s Mooring Sensor Systems
team. Here, another EAC deep-water mooring is deployed from the back deck of CSIRO’s RV Investigator. (Photo: Dr Thomas Moore/CSIRO)

Once harvested from the mooring array, these data are bound for processing and analysis for years to come by scientists across the world, including back home at CSIRO. Here, they are incorporated into climate modelling systems like ACCESS and CAFE60, the latter of which is operated by CSIRO’s Decadal Climate Forecasting Project.

These observations and models have opened the research world’s eyes to the impact and influence of ocean variability and change on life here in Australia and in our region.

For the Decadal Climate Forecasting team, who are working to improve and advance the use of near-term climate forecasts, ocean observations are combined with models to retrospectively analyse past ocean and atmospheric conditions.  The “ocean truth” collected at sea is also helping the team to validate and improve the models’ realism by gaining new insights into physical processes and is crucial to providing reliable forecasts.

Jamie Derrick from CSIRO’s Mooring Sensor Systems team cuts away the final safety pin before a deep-water mooring is deployed in the EAC. (Photo: Dr Thomas Moore/CSIRO)

Equipping industry and regulators to better manage climate

Dr Sloyan’s work – especially when positioned in the broader context of collaborative oceanography underway across the globe – is helping to realise the potential of a once-aspirational field of science: near-term climate predictions.

The idea is that by extending existing seasonal forecasts to multi-year and decadal timescales, providing industries and regulators with the ability to access climate predictions will enable them to better plan for climate variability and climate extremes.

The biggest challenge for the next twenty years in ocean observations is to maintain and expand an integrated observing system that provides the essential information required for a range of applications.

Dr Sloyan is passionate about this endeavour.

“It’s all about setting up integrated observation systems now to create continuous measurements and to keep them going – if we miss out on observations today, we lose our ability to address the climate challenges of the future.”

The current EAC mooring array is due for maintenance in April of next year. And while in these uncertain times planning a research voyage has some additional and daunting logistical complexities, the bluewater ocean team at CSIRO hasn’t stopped working towards the goal of keeping the continuous observational record intact.

Dr Chris Chapman keeps careful watch over CTD operations. (Photo: Dr Thomas Moore/CSIRO)

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