Photo: mage courtesy of SOCCOM

$53M project to deliver worldwide fleet of robotic ocean-monitoring floats

The US National Science Foundation (NSF) has approved a $53 million grant to a consortium of the country’s top ocean-research institutions to build a global network of chemical and biological sensors that will monitor ocean health.

Scientists at the Monterey Bay Aquarium Research Institute (MBARI), University of Washington, Scripps Institution of Oceanography at UC San Diego, Woods Hole Oceanographic Institution, and Princeton University will use this grant to build and deploy 500 robotic ocean-monitoring floats around the globe.

This new network of floats, called the Global Ocean Biogeochemistry Array (GO-BGC Array), will collect observations of ocean chemistry and biology between the surface and a depth of 2,000 metres. Data streaming from the float array will be made freely available within a day of being collected, and will be used by scores of researchers, educators, and policy makers around the world.

These data will allow scientists to pursue fundamental questions about ocean ecosystems, observe ecosystem health and productivity, and monitor the elemental cycles of carbon, oxygen, and nitrogen in the ocean through all seasons of the year.

Such data can improve computer models of ocean fisheries and climate, and to monitor and forecast the effects of ocean warming and ocean acidification on sea life.

Ocean-health observations only cover a tiny fraction of the ocean at any given time, leaving huge ocean regions unvisited for decades or longer.

A single robotic float costs the same as two days at sea on a research ship. But, floats can collect data autonomously for over five years, in all seasons, including during winter storms.

This illustration shows how biogeochemical floats spend most of their time 1,000 meters below the surface, then collect data and send it back to shore via satellite every 10 days. Image: Kim Fulton-Bennett 2020 MBARI

Argo

The first of these programs, the Argo array, consists of 3,900 robotic floats that drift through the deep ocean basins, providing information on temperature and salinity in the water column. The Argo array has done an incredible job of measuring the physical properties of our ocean, but Argo floats do not provide information about the ocean’s vital chemical and biological activity.

SOCCOM

Starting in 2014, the Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) program deployed a large array of robotic “biogeochemical” floats, based on the Argo design, but carrying sensors to monitor the chemical and biological properties of the ocean. These floats have already provided new information about how the Southern Ocean interacts with the Earth’s atmosphere and winter sea ice.

Similar to the SOCCOM floats, the new GO-BGC floats will carry a number of sensors in addition to the core Argo sensors for temperature, depth, and salinity. These include instruments to measure oxygen concentration, pH (ocean acidity), nitrate (an essential nutrient for microscopic algae), sunlight (required for algal growth), chlorophyll (an indicator of algal populations), and particles in the water (including microscopic algae).

The New Floats

Over the last few years, researchers have been testing, refining, and calibrating these sensitive instruments as part of the SOCCOM program and other international efforts.

The instruments on these floats will allow researchers to monitor the health of the ocean, including the growth and respiration of phytoplankton (drifting algae and microbes that use sunlight as a source of energy) and the nutrients and light that control these processes. In addition to supporting most of life in the ocean, including commercial fisheries, phytoplankton supply oxygen to and remove carbon dioxide from the ocean and the atmosphere. These microscopic plankton have huge impacts on our climate through their control on carbon dioxide.

The new floats will also provide first-hand data on long-term changes in the ocean, including ocean acidification and the expansion of low-oxygen zones.

This five-year effort involves five research institutions. MBARI will coordinate the project, refine the sensors, take the lead in processing data from the floats, and perform outreach for the program. The University of Washington, the Scripps Institution of Oceanography, and the Woods Hole Oceanographic Institute will build and deploy floats in collaboration with commercial partners. Finally, researchers at Princeton University will contribute to the array design and project management, and ensure that the data are linked to global computer models of the Earth’s ocean and climate.

This program will also have a significant impact on the ocean technology industry, including a number of commercial suppliers of ocean sensors and profiling floats.

The researchers hope that GO-BGC will inspire other countries to contribute similarly instrumented floats, as part of the new global biogeochemical ARGO effort. Ideally, this expanded network would grow to a sustained array of 1,000 biogeochemical floats uniformly distributed around the world ocean, and spaced about 1,000 kilometers (620 miles) apart.

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