December 7, 2019 | Published by | , ,

Picture (above): Indian Ocean islands from the air. Credit: Nattu Adnan (Unsplash).

At the time of writing New South Wales is blanketed with smoke amid unseasonably hot weather while further south Tasmania and the Victorian Alps are experiencing late-season snowfalls. It sounds like wildly unpredictable weather patterns but research produced by the Variability and Teleconnections team in early October forecast the likelihood of this type of weather following a sudden stratospheric warming event over Antarctica. It’s yet another example of how seemingly unrelated distant events can have a powerful impact on Australia and goes to the heart of a very active four-month period for our research program.

Another important influence on the hot and dry conditions being experienced in Australia is the Indian Ocean. A strongly positive Indian Ocean Dipole has reduced rainfall across much of the country. It shows how ocean temperatures in that part of the world play an important role in our climate and why understanding how they change is vital for projections at a seasonal level and beyond. Research by Nathan Bindoff and colleagues has uncovered new insights into how heat moves from the ocean to the atmosphere over the Indian Ocean, which will improve how this is represented in climate models.

Underpinning this work are key observations derived from the Indian Ocean Observing System. Chief investigator Peter Strutton has been playing an important role in planning the future of the system and was one of a number of authors that outlined the future directions for the System and its importance to the societies around the Indian Ocean and beyond.

To get a sense of how important the Indian Ocean is on an international scale there is no need to go further than a paper by Ryan Holmes and colleagues. This paper showed how the heat generated in the Indian Ocean actually influences major currents in the Atlantic Ocean that are key climate drivers for the US, Europe, South America and East African nations.

But as anyone with an interest in climate science knows the Indian Ocean isn’t the only influence on our climate. The Pacific Ocean is home to one of our most powerful climate influences, the El Niño Southern Oscillation. It has long been assumed that the extreme heat and extreme convection coincided under very strong El Niño events. However, new research by Agus Santoso and colleagues has shown that, as El Niño’s change with global warming, this may not always be the case. It is yet another indication that the planet warms our expectations of the behaviour of seasonal events will have to change.

The Southern Ocean is another ocean area that impacts Australia’s climate but it is also one of the most powerful drivers of ocean circulation around the world. It will play a key role in how global oceans respond to climate change. New research by CLEX researchers with US colleagues has found that the increase in wind speeds across the Southern Ocean and the shift of these wind tracks towards Antarctica will have an impact on how well this important ocean absorbs heat and carbon from the atmosphere.

The increase in wind speeds in this region has seen more energy enter the ocean that have expressed themselves as high-frequency motions but it has been unclear how the vortices in this part of the world have responded. The response of these vortices is important because they play a key role in controlling climate. Using satellite measurements, CLEX researchers found that the energy went into increasing the strength of these vortices rather than increasing their number.

Another important area of research in understanding how global warming may affect the Southern Ocean and by extension Australia and the rest of the world is to gain insight into how ocean heat moves from the surface to the depths and vice versa. While we have a relatively good understanding of this process near the surface the abyssal depths still remain something of a mystery. One way of tracking this is through using synthetic traces, however, we have little understanding how they disperse at these depths and therefore how effective they may be. Using an ocean model, CLEX researchers were able to simulate how these tracers would behave on or near the ocean floor and test their usefulness at depth. This gave the researchers an insight into the capacity and limitations of such an approach.

Another issue at depth is the influence that the ocean floor has on the Antarctic circumpolar current, which is the strongest ocean current in the world and is responsible for powering much of the oceanic circulation. Fascinating research by Navid Constantinou and Andy Hogg found that in certain regions the strength of the current was predominantly affected by the topography at the bottom of the ocean. This adds further complexity to the eddy, wind, current relationships in the Southern Ocean.

Another area of strong international interest is the movement of circumpolar water from the Antarctic ice shelf to the depths. This has important implications for the speed of ice melt around the frozen continent and also global ocean circulation. Taking a very novel approach, CLEX researchers and colleagues tagged seals with observational instruments that allowed them to track temperature changes through the water column close to these ice shelves. It was found that eddies played the most important role in this transfer of heat, salt and high-density water.

Much of this new information about the Southern Ocean feeds into our climate models that are used to project the impacts of a changing climate. These climate models required supercomputers that involve considerable computer time to get their results. Work by Craig Bishop and colleagues will help reduce this time after they developed a new technique for an Ensemble Kalman Filter that also improves its results.

Understanding ocean currents and does more than help us understand our changing climate. Two fascinating pieces of research have evolved out of our ocean models. Close to home, Joe Scutt Phillips was able to model the movement of fish attracting devices across key tuna fishing grounds to the north and northeast of Australia. His research will have a direct impact on the economies of the small Pacific nations who are our neighbours.

Sometimes, this research can take us entirely away from planet Earth. Continuing research that he did before coming to CLEX, Navid Constantinou put out a paper that revealed how magnetic fields could influence with fluids. This research has been used to explain some of the mysteries of Jupiter’s zonal winds and produce the colourful stripes on that planet that we know so well from photographs.

When it comes to reaching beyond the local, the researchers in the Variability and Teleconnections program have themselves made quite an impact. It has been an extraordinary four months for many members of the team at a professional level.

The Consortium for Ocean-Sea Ice Modelling in Australia (COSIMA) community founded by RP4 members continues to expand with its 4th annual meeting held at ANU in early September. It was great to see that for the first time the two-day workshop was streamed live – an innovation we hope to see more of in the future.

Andrea Taschetto was named as a member of the basin interaction group in the new CLIVAR foci, Tropical Basin Interaction (TBI). The main goal of TBI is to elucidate the complex two-way interaction between the tropical basins and to quantify the benefit to climate prediction.

PhD student Sarah Jackson was awarded a fellowship from the Scientific Committee for Antarctic Research (SCAR). The fellowship will allow Sarah to collaborate with researchers from the British Antarctic Survey to study the climate information preserved in the d17O-excess record from an Antarctic Peninsula ice core. This will complement her PhD research where she is applying this same technique to the Mount Brown South ice core from East Antarctica, which will provide a 1000-year long record of climate variability in the Indian Ocean sector of Antarctica.

And of course we can’t ignore the important roles Nerilie Abram and Nathan Bindoff played in the IPCC Special Report on Ocean and Cryosphere in a Changing Climate, released on September 25. After an extraordinary final meeting, both had plenty of media duties and performed them exceptionally well.

The recognition for our researchers keeps on coming. Amelie Meyer has had an outstanding four months, winning the Young Tall Poppy Science Award for Tasmania and being awarded a DECRA over a few short weeks.

Matthew England was named as a 2019 Highly Cited Researcher by Web of Science, based on citations over the past decade. Fewer than 0.1%, of the world’s researchers earn this distinction. 

Scott Power received an Innovation and Research Contribution Award from the Pacific Meteorological Council “in recognition of outstanding, innovative and exceptional climate change and climate variability research” and “for empowering the next generation of researchers”.

Violaine Pellichero won the Thesis Prize Albert de Monaco from the Oceanographic Institute of Monaco. The prize is awarded each year to a young researcher for work in an ocean discipline in a French doctoral school.

Paul Spence was awarded a Future Fellowship to study the changes in ocean circulation around the Antarctic as a result of climate change and the potential impact on rising sea levels.

Agus Santoso received an Editors Award at the 100th AMS meeting for consistently high-quality reviews on various topics in tropical climate dynamics in the Journal of Climate.

To top it all off three RP4 researchers took home an annual CLEX award. The best published paper by an honours, masters or PhD student went to Sonja. The prize for best published paper by an early career researcher was won by Navid Constantinou and the CLEX Director’s Prize went to Amelie Meyer. This is a great result for the program and three very deserving winners.

In an effort to prove that we are about more than just science we can’t fail to note

Matthew England’s turn treading the boards at the Sydney Fringe Festival as part of the performance, The Poet’s Guide to Science – a sceptic think tank.

Continuing our highlight of RP4’s science creatives, congratulations also go to Linden Ashcroft who had her article Letter to a weather station published in The Best Australian Science Writing 2019 Anthology, edited by Bianca Nogrady.  

Amidst all this work and achievement, the Variability and Teleconnections program hosted and collaborated with high quality list of visitors.

Director of NASA GISS Gavin Schmidt visited the CLEX UNSW node for the next five weeks where he collaborated with Matthew England and presented a three-part workshop on science communication.

Shunji Kotsuki from RIKEN Center for Computational Science (R-CCS), visited our University of Melbourne node where he worked with Craig Bishop over four weeks.

Hendrik Dijkstra from the Institute for Marine and Atmospheric Research, Utrecht University is still with us as part of sabbatical visit at the ANU where he is collaborating with Andy Hogg.

Sujata Murty from the Woods Hole Oceanographic Institution visited Nerilie Abram.

William Young from the Scripps Institution of Oceanography visited ANU to collaborate with Navid Constantinou and other ANU based researchers.

Finally, Gabriel Pontes, a research practicum student from Brazil, will be at the UNSW for the coming year doing part of his PhD research with Andrea Taschetto. All in all, it has been a very busy end to our year setting up a year ahead where we hope to kick many more research goals.