Eddies — circular currents of water — move deep water nutrients to the surface, but their overall effect on the Southern Ocean and the earth’s changing climate is barely understood.
The Southern Ocean, also called the Antarctic Ocean or the Austral Ocean, has high species abundance and diversity, making common and highly specialised species thrive .
Sailing the seas for longer periods has become inadequate to help scientists in South Africa unravel the underlying mysteries.
But thanks to robotic gliders, the Southern Ocean Carbon and Climate Observatory (SOCCO) researchers under the South Africa’s Council for Scientific and Industrial Research (CSIR) are observing the ocean’s physical processes, studying their impacts on carbon dioxide exchange between the atmosphere and ocean, and the growth of phytoplankton – microscopic algae that live on the ocean surface.
“These cutting-edge robotic gliders will shape the future of marine research and environmental monitoring of the Southern Ocean and South African waters,” says Sebastiaan Swart, a principal scientist with the CSIR.
The data may reveal how human activity is changing the planet, he hopes.
The Southern Ocean accounts for 50 per cent of all carbon dioxide absorbed by the oceans, Sandy Thomalla, a CSIR senior researcher, writes in SOCCO bulletin. 
“These cutting-edge robotic gliders will shape the future of marine research and environmental monitoring of the Southern Ocean and South African waters.”
Sebastiaan Swart, South Africa’s Council for Scientific and Industrial Research (CSIR)
For Swart, sensitivity of the Southern Ocean to climate change is a prime concern because the creatures living there are susceptible to minor environmental shifts, possibly leading to large changes in global ocean currents.
“Our one [of] research gaps that we hope to address with these gliders, in conjunction with satellites and computer models, is better understanding the role of small-scale features such as ocean eddies and currents and short term events [storms] on the overall state of the ocean,” Swart says.
Before glider technology was available, he says, measuring these forms of features and variability were impossible — investigations from research ships and satellite data alone were not enough.
Diving new depths
September 2012 marked the first Southern Ocean glider deployments near the remote Gough Island, about 2000 kilometres south west of Cape Town. Gliders collected and sent data back from one of the world’s harshest environments directly to scientists at CSIR for six months.
Satellite communications were remotely used to control the location and depth of the robots, according to Swart and colleagues, in an article published in the South African Journal of Science in 2012. 
Since then, Swart says, additional long-endurance robotics experiments have taken place on an annual basis.
“Enhancing our understanding of how the Southern Ocean works and interacts with climate today will leave us in a position to better mitigate the effects of climate change tomorrow,” he says.
The robotic gliders fleet totals nine — and could increase to match growing needs of the global researchers. Four surface wave gliders ride the ocean surface measuring CO₂, acidity, among other surface ocean physical variables. Five profiling gliders can dive to a maximum depth of one kilometre below the ocean surface, Stewart tells SciDev.Net.
When deployed, the gliders “tweet” data to scientists in Cape Town where it is stored, analysed and eventually made available to the global researchers, explains Swart.
CSIR researchers combine analysis of data from surface wave and profiling gliders by pairing them together while deployed in the ocean, providing a complete picture of changes in the water, he adds.
The gliders are manufactured in the United States, but modified in South Africa through adding and building new sensors to suit local needs, and maintained by the CSIR-led South Africa Marine Engineering and Robotics Centre (SAMERC), and a marine technology company, Sea Technology Services.
Swart, one of South Africa’s architects of robotic ocean glider programme, values imparting expertise in using the ocean gliders to engineering students at SAMERC by South African marine engineers.
He says students gain, unique and advanced skills, which can be expanded across the rest of the continent as they complete their in-service at the centre.
Yearly young black South African engineers are trained to use this advanced ocean technology, particularly the use of robots and scientific sensors, he says, adding are young marine scientists have been graduating from the country’s universities.
Each year, the gliders are sent out to collect more data from the severe Southern Ocean environment, Swart told SciDev.Net at the beginning of the fourth Southern Ocean robotics experiment in October last year.
Four gliders were deployed from the SA Agulhas II, South Africa’s Antarctic research vessel, in the frigid and stormy winter sea.
“Ocean prediction is an initial condition problem, so if we can improve our ocean state estimate at the nowcast stage, then we improve our forecast skill for tomorrow.”
Björn Backeberg, University of Cape Town
“We hope these gliders will continue making measurements until late summer in 2016 or approximately a year in total,” he says.
Marjolaine Krug, a senior CSIR researcher with the Ecosystem Earth Observation group, led a six-week experiment offshore of Port Elizabeth — the site of a strong current along South Africa’s east coast in April 2015, demonstrating the tough possibility for the gliders to navigate and collect data in areas dominated by strong currents.
Boosting ocean research
“Ocean models must be combined with ocean observations in order to limit model errors at the nowcast [short-term weather forecast] stage to provide a better estimate of the ocean state,” says Björn Backeberg, an oceanographer and a co-director of South Africa-based University of Cape Town’s Nansen-Tutu Centre for Marine Environmental Research. “Ocean prediction is an initial condition problem, so if we can improve our ocean state estimate at the nowcast stage, then we improve our forecast skill for tomorrow.”
Backeberg adds that historical reliance on measurements gathered by ships to obtain data on the ocean interior was incredibly expensive due to the large running costs of the ships.
He explains that robots are cheaper at collecting data in severe ocean conditions, and depending on battery power gliders can collect high-resolution information for up to six months and provide consistent data throughout the year. Moreover, a ship at sea for three months is much more expensive and observations generally more sporadic in both space and time.
Hiring the research vessel, SA Agulhas II costs approximately 300,000 rand (about US$18,000) a day. A deployed glider daily costs far less — about 3,000 rand (about US$181).
The future of marine conservation?
According to Backeberg the information collected by these robots now provides a vital component to understanding of fish stock health, fish migration and distribution patterns, although some challenges remain.
“[The gliders] rely on acoustic [sound] measurements to estimate fish stock sizes, but acoustic measurements are unable to tell you what type of fish is being monitored, he says, noting that ship measurements and stock assessment trawls are required to help researchers address this challenge.
Still, Backeberg backs the use of unmanned robots as an important component of future marine conservation to monitor the ocean in combination with existing methods, such as ship surveys and satellite measurements.
Huge economic benefits promise exists
Efforts to improve ocean governance and resource management through technology will be able to feed directly into South Africa’s initiative to unlock the potential of its “blue” economy, dubbed Operation Phakisa, Swart says.
President Jacob Zuma of South Africa launched the Phakisa programme in October 2014 to maximise the enormous economic potential of oceans while preserving them. Zuma said ocean activity contributed 54 billion rand (about US$3.2 million) to South Africa’s economy and accounted for about 316,000 jobs in 2010. 
Swart sees successful glider research missions potentially leading to economic growth.
“Gliders are a key part of unlocking the wealth of our ocean blue economy. They can assist in understanding the ocean, protecting and managing its resources, and manage disasters and pollution,” he says.
Disclaimer: Internews’ Environmental Journalism Network sponsored Munyaradzi Makoni to write this article.
This piece was produced by SciDev.Net’s Sub-Saharan Africa English desk.