NASA satellite shows small ocean swirls may affect climate
A NASA-led satellite mission has suggested that swirls and eddies in the middle of the ocean have a bigger influence on Earth’s climate system than scientists previously realized.
Measuring changes in the Earth’s oceans has been a huge challenge for scientists owing to their vastness and inaccessibility. While satellite data has helped revolutionize modern oceanography, there are limits to the level of detail scientists can record.
To help address the problem, in December 2022 NASA launched its Surface Water and Ocean Topography (SWOT) satellite, which aims to measure the height of water in freshwater and ocean environments.
While previous satellites’ altimetry sensors struggled to resolve ocean features smaller than 100 km, SWOT was designed [PDF] to capture them in detail. Its Ka-band Radar Interferometer scans 120-km-wide swaths of sea surface height, delivering two-dimensional measurements with far greater resolution and lower noise than earlier altimeters. The satellite’s 21-day orbit enables repeated global coverage — though with limited temporal resolution.
The paper published in Nature today marks the first global view of submesoscale ocean dynamics from the SWOT satellite. These small-scale features – spanning just 1 to 100 kilometers – include eddies and internal waves whose dynamics and energy content had never been observed from a global perspective. Though small, scientists believe they influence the transport of heat, carbon, and nutrients between surface and interior layers.
SWOT ushers in a new era of global ocean observing, placing [small-scale] ocean dynamics as a critical element of the Earth’s climate system
“These processes are crucial in regulating Earth’s climate, yet they have mostly been under the radar for oceanographers — almost literally,” said Elisa Carli, a research fellow in physical oceanography at the European Space Agency, in an accompanying article.
“These findings confirm that SWOT will be able to quantify kinetic-energy fluxes precisely, down to scales of around 10 km — a giant step in understanding ocean dynamics,” Carli said.
The researchers, led by NASA Jet Propulsion Lab research scientist Matthew Archer, said that the new data from the SWOT satellite not only confirm the characteristics of small-scale ocean features “but also suggest that their potential impacts on ocean energetics, the marine ecosystem, atmospheric weather and Earth’s climate system are much larger than anticipated.
“SWOT ushers in a new era of global ocean observing, placing [small-scale] ocean dynamics as a critical element of the Earth’s climate system,” the paper said.
However, Carli’s article points out that further work is needed to provide more detail, and calls for joint projects with other research teams.
“SWOT is a unique instrument that opens doors to explore unknown global and local ocean dynamics. The first results place [small-scale] ocean dynamics as a crucial element of Earth’s climate system. Exploiting all available data is a long process that will take years. But strong collaboration between the climate and data-science communities will lead to better understanding, prediction and protection of the ocean and of the whole climate system,” she said.
Observers of US politics of the last few months might fear for the prospect of such work. The Trump Administration is reportedly set to slash NASA’s science budget by nearly 50 percent, including significant cuts to climate research.
NASA’s JPL has been offered the opportunity to comment. ®
