UMaine’s Boss Participates in Study of Southern Ocean’s Role in Climate Regulation

The Southern Ocean that encircles Antarctica lends a considerable hand in keeping Earth’s temperature hospitable by soaking up half of the human-made carbon in the atmosphere and a majority of the planet’s excess heat.

Yet, the inner workings — and global importance — of this ocean that accounts for 30 percent of the world’s ocean area remain relatively unknown to scientists, as dangerous seas have hindered observations.

Princeton University and 10 partner institutions seek to make the Southern Ocean better known scientifically and publicly through a $21 million program that will create a biogeochemical and physical portrait of the ocean using hundreds of robotic floats deployed around Antarctica.

In addition, NASA awarded $600,000 to the University of Maine, in collaboration with Rutgers University and scientists from the above project, for a complementary project that equips the floats with bio-optical sensors that gather data about biological processes in the water column.

UMaine oceanographer Emmanuel Boss, an expert in marine optics and in the use of optical sensors to study ocean biogeochemistry, is leading the companion project.

The Southern Ocean Carbon and Climate Observations and Modeling program, or SOCCOM, is a six-year initiative headquartered at Princeton and funded by the National Science Foundation’s Division of Polar Programs, with additional support from the National Oceanic and Atmospheric Administration (NOAA) and NASA.

“SOCCOM will enable top scientists from institutions around the country to work together on Southern Ocean research in ways that would not otherwise be possible,” says SOCCOM director Jorge Sarmiento, Princeton’s George J. Magee Professor of Geoscience and Geological Engineering and director of the Program in Atmospheric and Oceanic Sciences.

“The scarcity of observations in the Southern Ocean and inadequacy of earlier models, combined with its importance to the Earth’s carbon and climate systems, mean there is tremendous potential for groundbreaking research in this region,” Sarmiento says.

About 200 floats outfitted with biogeochemical sensors that provide near-continuous information related to the ocean’s carbon, nutrient (nitrate, in particular) and oxygen content, both at and deep beneath the surface, are central to the study.

The floats are augmented biogeochemical versions of the nearly 4,000 Argo floats deployed worldwide to measure ocean salinity and temperature. SOCCOM marks the first large-scale deployment of these biogeochemical floats.

“These floats are revolutionary and this major new observational initiative will give us unprecedented year-round coverage of biogeochemistry in the Southern Ocean,” Sarmiento says.

The floats will increase the monthly data currently coming out of the Southern Ocean by 10 to 30 times, Sarmiento says.

The data will be used to improve recently developed high-resolution earth-system models, which will advance understanding of the Southern Ocean and allow for projections of Earth’s climate and biogeochemical trajectory.

Boss says the additional optical sensors measure backscattering of light, which provides information about particles — including bacteria and phytoplankton in the water — and measure chlorophyll fluorescence — a pigment unique to phytoplankton.

The information will help NASA verify data that its satellites glean daily, extend the product to depth, and help improve currently used algorithms.

In keeping with SOCCOM’s knowledge sharing, or “broader impacts,” component, all the information collected will be freely available to the public, researchers and industry.

SOCCOM will provide direct observations to further understand the importance of the Southern Ocean as suggested by models and ocean studies. Aside from carbon and heat uptake, models have indicated the Southern Ocean delivers nutrients to lower-latitude surface waters that are critical to ocean ecosystems around the world.

In addition, the impacts of ocean acidification as levels of carbon dioxide in the atmosphere increase are projected to be most severe in the Southern Ocean.

Boss says the Southern Ocean — the second smallest of the planet’s five primary oceans — has a disproportionate role in climate regulation. Carbon stored deep in the ocean comes to the surface here and some is released into the atmosphere — however, given the increase in atmospheric CO2 in past decades, much less is released than would be expected.

He says there is still much to learn about this ocean’s significant role in climate regulation.

“It’s a hard area to study,” Boss says of the ocean that encircles Antarctica. “Because there are no barriers, the current is extremely strong. It has some of the roughest seas in the world.”

Other than administering the project, Sarmiento and other Princeton researchers will co-lead the modeling and broader impacts components, as well as coordinated data management. Researchers from NOAA’s Geophysical Fluid Dynamics Laboratory housed on Princeton’s Forrestal Campus will carry out high-resolution earth-system simulations in support of the modeling effort, which is led by the University of Arizona and includes collaborators from the University of Miami.

The floats will be constructed at the University of Washington with sensors from the Monterey Bay Aquarium Research Institute; NOAA’s Climate Program Office will provide half of the basic Argo floats. Float deployment, observation analysis and data assimilation will be led by the Scripps Institution of Oceanography at the University of California-San Diego. Climate Central, a nonprofit science and journalism organization based in Princeton, will oversee the broader-impacts component. Researchers from Oregon State University and NOAA will develop the floats’ carbon algorithms.

Contact: Beth Staples, 207.581.3777