South Africa’s ocean gliders are already making unprecedented impact on the Southern Ocean Carbon and Climate Observatory’s (SOCCO) research by providing extended time series of physical and biogeochemical observations in the heart of the Antarctic Circumpolar Current (ACC) at unprecedented spatial and temporal scales. Their previous long term mission, the Southern Ocean Seasonal Cycle Experiment (SOSCEx, Swart et al., 2012) was conducted between September 2012 and March 2013, when five state-of-the-art autonomous Seagliders were deployed in the Southern Ocean from aboard South Africa’s newest polar ship, the SA Agulhas II. The gliders observed the SAZ region of the SE Atlantic-Southern Ocean for six months, while being carefully navigated remotely via satellite communications by glider pilots back on dry land in Cape Town. By the end of the experiment the gliders had managed to complete over 5000 profiles of the water column between the surface and 1 km depth, while covering a total horizontal distance of 7000 km – equivalent to the distance between Cape Town and Rio de Janeiro.
SOCCO recently acquired a newer form of ocean robot, the wave glider, which is a wave powered surface platform measuring surface fluxes, in this case CO2 and O2, between the ocean and the atmosphere. As a follow on to the SOSCEx experiment and in collaboration with NOAA-PMEL, in the USA, a wave glider and a Seaglider will be simultaneously deployed in the Subantarctic Zone in early September 2013. The two types of gliders will then be piloted and kept together to follow the GoodHope monitoring line southwards towards the Antarctic, while observing both the physical dynamics and biogeochemical parameters in the subsurface ocean while also acquiring CO2 and O2 gas flux measurements on the surface ocean. By early December 2013, a second set of deployments will see another tandem deployment of gliders in the marginal sea ice region of the northern Weddell Sea. The combined measurements made by the two types of gliders provide a unique view of the ocean-atmosphere state over the austral spring-summer-autumn seasonal cycle, providing valuable data that allows for novel carbon-climate related research to take place.
Extensive experiments made using autonomous platforms in the Southern Ocean, such as SOSCEx, highlight the value these platforms have in establishing an observing system in the Southern Ocean. The combined effect of the remote, harsh environment and the lack of continuous observations made outside of the austral summer sampling window in the Southern Ocean, make these robots ideal platforms to support SOOS and its 20-year vision (Meredith et al., 2013).
A) Autonomous platforms battle the effects of bio-fouling in the ocean. Here Goose-Neck Barnacles grow prolifically on the glider body and sensors, altering its ability to efficiently profile the water column and collect quality measurements. B) Ocean technician Gavin Tutt (left) and senior research Dr. Sebastiaan Swart (right) deploy a Seaglider into the Southern Ocean. C) Newly aquired CO2 measuring wave glider being transported in Cape Town, South Africa before deployment into the Sub-Antarctic Zone.
Data will be submitted to the South African Data Centre for Oceanography (SADCO), after which the data will be distributed to the appropriate data streams to make it available to the community.
Authors and Contact
Sebastiaan Swart and Pedro MS Monteiro (The Southern Ocean Carbon and Climate Observatory, CSIR, Cape Town, South Africa)
We thank APL at the University of Washington for hosting us on the Integrative Observational Platforms (IOP) for the past year and NOAA-PMEL in set up and operations of CO2 sensors on wave gliders. Engineers, Derek Needham Andre Hoek (Sea Technology Services), and technical interns, Sinekaya Bilana and Jean-Pierre Smit are essential to the smooth running of the robotics operations. This research is funded by DST-CAPEX, CSIR-PG, SANAP-NRF and CSIR-YREF grants.
Meredith MP, et al. 2013: The vision for a Southern Ocean Observing System, Current Opinions in Environmental Sustainability, http://dx.doi.org/10.1016/j.cosust.2013.03.002
Swart S., et al., 2012: Southern Ocean Seasonal Cycle Experiment 2012: Seasonal scale climate and carbon cycle links. South African Journal of Science, 108(3/4), doi.org/10.4102/sajs.v108i3/4.1089.