As part of a year-long experiment led by scientists from the UK’s National Oceanography Centre (NOC), a fleet of ocean robots and instruments has been deployed to explore the climate-regulating mechanism at the depths of the Labrador Sea.
Project goals
The ReBELS project (Resolving Biological Carbon Export in the Labrador Sea) is a four-year program funded by the Natural Environment Research Council (NERC). By deploying technology, the project is investigating the biological carbon pump, an ocean process that helps remove carbon dioxide from the atmosphere and store it in the deep sea; without it, atmospheric CO2 would be 50% higher. The aim is to provide new insights into the ocean’s important climate-regulating mechanism and improve the ability to predict and respond to global climate change.
Using a combination of moored sensors, drifting profiling floats and autonomous underwater vehicles, the project seeks to understand how carbon-rich particles sink through the water column and how physical ocean processes, such as deep convection currents, might enhance carbon storage in this remote and understudied region.
Technology deployed
Two FluxCAM marine snow camera systems were installed on a deep-sea mooring in the Labrador Sea to measure the sinking speeds of different-sized particles and reduce uncertainties about how much carbon the ocean absorbs from the atmosphere. The cameras were fixed at depths of 100-300m on a 3,300m-long mooring in the sea between Newfoundland and Greenland. They were deployed with a specially programmed drifting profiling float and autonomous underwater gliders, which will measure ocean properties and carbon flux for five to six months.
“The biological carbon pump plays a crucial role in regulating Earth’s climate,” said Dr Filipa Carvalho, project lead at NOC. “Microscopic marine plants, known as phytoplankton, absorb carbon dioxide from the atmosphere and convert it into organic material.
“This material is then consumed by marine organisms, with remnants eventually sinking as ‘marine snow’ – tiny carbon-rich particles that settle in the deep ocean, where the carbon can be stored for centuries.
“However, the rate at which these particles sink and how much carbon is ultimately locked away remain uncertain. The ReBELS project is using cutting-edge technology to answer these questions. This combination of fixed and mobile instruments will allow us to track how carbon is transported and transformed in the Labrador Sea over time.”
The ReBELS float has been programmed to carry out more frequent and varied depth profiles than standard floats and is also equipped with advanced sensors, including an optical sediment trap to help researchers understand the amount of sinking particles when the float is drifting at the same depth.
One of the gliders will stay near the mooring while another will follow a drifting profiling float, capturing detailed, high-resolution data on particle movement, ocean circulation and biological activity.
“This combination of moored sensors, drifting instruments and mobile gliders is designed to overcome the challenges of studying carbon flux in the ocean,” added Dr Louis Clément, co-investigator and also at NOC.
“While moored instruments provide long-term, fixed-location data, they do not capture the movement of water masses. The drifting float follows ocean currents, providing a dynamic perspective on sinking particles, while the gliders add another layer of insight, especially into small-scale turbulence effects on the biological carbon pump. By integrating data from these platforms, we hope to build the most accurate picture yet of carbon transport and storage in the Labrador Sea.”
In related news, Caltech recently conducted a research project using the submarine robot CARL-Bot (Caltech Autonomous Reinforcement Learning roBot) to study how ‘vortex rings’ in the oceans could help small autonomous underwater vehicles navigate better, and therefore improve their measurements of the deep. Click here to read the full story.