NASA satellite is rewriting what we know about ocean currents

When we picture the ocean, it’s often the massive waves that come to mind. But scientists are finding that some of the most important activity happens on a much smaller scale.

Thanks to a new satellite mission, researchers are now seeing the ocean’s tiny waves and swirling currents in clearer detail than ever before – and it’s changing the way we understand life in the sea.

In a recent study led by NASA and researchers at Texas A&M University, scientists used the Surface Water and Ocean Topography (SWOT) satellite to analyze ocean features too small for earlier satellites to detect.

These features, known as submesoscale eddies and waves, are often just a mile wide, but they play a powerful role in how heat and nutrients move throughout marine ecosystems.

What we’ve been missing

For years, scientists have known about these small ocean features. Apollo astronauts even spotted them from space nearly 50 years ago.

But the tools available – whether ship-based instruments or older satellites – could only capture bits and pieces. They either missed the full scale or couldn’t provide a global view.

SWOT is filling that gap. A joint project between NASA and the French space agency CNES, the satellite collects detailed, two-dimensional images of the ocean surface. These images help researchers track how water is moving – and what it’s carrying – around the globe.

“The role that submesoscale features play in ocean dynamics is what makes them important,” said Matthew Archer, an oceanographer at NASA’s Jet Propulsion Laboratory.

“Vertical currents move heat between the atmosphere and ocean, and in submesoscale eddies, can actually bring up heat from the deep ocean to the surface, warming the atmosphere.”

That movement goes both ways. Just as heat can rise from deep ocean layers, nutrients can, too. These nutrients are critical to marine life, acting like food trucks arriving with supplies for surface-dwelling organisms.

“Not only can we see the surface of the ocean at 10 times the resolution of before, we can also infer how water and materials are moving at depth,” noted Nadya Vinogradova Shiffer, SWOT program scientist at NASA Headquarters in Washington.

How the ocean talks to the sky

The SWOT satellite doesn’t just map where the water is. It also measures the height of ocean surfaces.

From that data, scientists can estimate wave slopes and pressure levels, which reveal how strong the forces are in these currents. This helps to determine how fast water is moving and how much heat, energy, or nutrients are being transported.

“Force is the fundamental quantity driving fluid motion,” said study co-author Jinbo Wang, an oceanographer at Texas A&M University in College Station.

Scientists will now gain a better understanding of how the ocean and atmosphere interact. A small change in one can have a big effect on the other. For example, if warmer water reaches the surface, it can influence weather patterns and even climate.

A closer look at ocean currents

To test SWOT’s capabilities, scientists focused on two ocean features. One was a swirling eddy in an offshoot of the Kuroshio Current, a major Pacific Ocean current near Japan.

SWOT was able to spot the eddy and measure how fast water inside it was moving vertically. The estimate? Between 20 and 45 feet per day.

While the measurement may sound modest, capturing this kind of motion at a global scale is new – and vital. It’s the first step toward a better understanding of how deep-sea energy and nutrients reach the ocean surface.

The second example involved a different kind of submesoscale feature: an internal solitary wave. These waves form when tidal forces move water over underwater plateaus.

SWOT caught one of these waves in the Andaman Sea near Myanmar. When researchers did the math, they found that this single wave had at least twice the energy of a typical internal tide in the area.

Better models, better predictions

Information from SWOT will help researchers refine their models of ocean circulation. According to study co-author and project scientist Lee Fu, a lot of ocean models were trained to show large features, like eddies that are hundreds of miles across.

“Now they have to learn to model these smaller scale features. That’s what SWOT data is helping with,” noted Lee.

Researchers have already started to incorporate SWOT ocean data into some models, including NASA’s ECCO (Estimating the Circulation and Climate of the Ocean).

It may take some time until SWOT data is fully a part of models like ECCO. But once it is, the information will help researchers better understand how the ocean ecosystem will react to a changing world.

Image Credit: NASA’s Scientific Visualization Studio

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–