Small ocean currents play a huge role in Earth's climate

What if some of the ocean’s smallest currents turned out to be some of the most powerful forces shaping Earth’s climate? New research is finally giving scientists a detailed look at these elusive ocean features.

The research was led by scientists from Texas A&M University, working in collaboration with NASA’s Jet Propulsion Laboratory (JPL), the Centre National d’Études Spatiales (CNES), and Caltech.

The findings mark a major step forward for a $1 billion international mission that’s been over 20 years in the making.

The hidden power of ocean eddies

An eddy is like a giant whirlpool in the ocean. Imagine the swirling water you see behind a rock in a river. Now picture that on a massive scale.

Some ocean eddies stretch hundreds of kilometers and help move heat, nutrients, and energy around the planet. They play a vital role in weather, climate, and marine ecosystems.

While larger eddies have been studied for years, smaller ones – known as submesoscale eddies – have remained largely invisible.

These eddies, which range from a few kilometers to about 100 kilometers wide, are difficult to detect. For scientists, they’ve been the missing pieces of the ocean’s climate puzzle.

A clear view of small ocean currents

Using new data from the Surface Water and Ocean Topography (SWOT) satellite, the team was finally able to capture a clear picture of these small, swirling currents.

“For the first time, we can directly observe small-scale ocean processes across the globe. And it turns out they are a lot stronger than we thought,” said Jinbo Wang, associate professor in the Department of Oceanography at Texas A&M University.

The SWOT satellite carries a Ka-band radar interferometer that measures tiny changes in sea surface height with millimeter precision. This technology has revealed swirling eddies and internal ocean waves that had never been seen from space before.

“These smaller currents carry surprisingly large amounts of energy,” Wang explained. “They play a huge role in moving heat between the upper and deeper parts of the ocean and shaping how the ocean sustains its ecosystem and interacts with the atmosphere.”

‘That means they can influence marine food webs and weather patterns, like how hurricanes form and where they go, or how events like El Niño and La Niña develop. These are not just ocean features – they connect directly to the climate systems that impact all of us.”

Surprising performance of SWOT

The satellite’s performance exceeded many scientists’ expectations. Although SWOT was designed to meet strict science requirements, there was uncertainty about whether it could detect such subtle changes.

“I was pessimistic about the expected outcome before the satellite launch,” Wang said. “But the satellite performed four times better than expected. That surprise is what made this breakthrough possible.”

With these high-quality observations, the researchers showed that small-scale motions – especially the spiral-shaped eddies and long internal solitary waves – are much stronger and more common than once thought.

These movements mix warm and cold waters and move energy across vast distances, influencing ocean circulation, weather, and climate. The new data will help scientists refine their climate prediction models.

Teamwork across decades

This research stems from the SWOT mission, a collaboration between NASA and CNES, with support from the U.K. and Canadian space agencies. It took over two decades of teamwork, testing, and innovation to reach this point.

“We’re building on work that started two decades ago,” said Dr. Shari Yvon-Lewis, head of the Texas A&M Oceanography Department. “Many people who helped design this satellite and the science have since retired. It’s a tribute to long-term vision, teamwork and dedication.”

Beyond this project, Wang also leads a NASA Ocean AI working group that explores how artificial intelligence and machine learning can improve the analysis of satellite data and aid the design of future missions. He is already thinking about the next steps for satellite technology.

For now, having this work is a milestone to celebrate – and a reminder of how much more the ocean has to reveal. “This is just the beginning,” Wang said. “We finally have the tools to see what’s been hiding in plain sight.”

The full study was published in the journal Nature.

Image Credit: NASA/JPL/SWOT/CNES

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