A groundbreaking international study published in Nature in April 2025 has unveiled the critical role of previously elusive small-scale ocean features in global marine dynamics. Utilizing data from the Surface Water and Ocean Topography (SWOT) satellite—a collaborative mission between NASA and the French space agency CNES—scientists have gained an unprecedented two-dimensional view of ocean waves and currents as small as a mile across. These so-called submesoscale phenomena are now shown to play a vital part in transporting heat, nutrients, carbon, and energy within the ocean, reshaping our understanding of the ocean’s influence on Earth’s climate and ecosystems.
Unlocking the Dynamics of Submesoscale Ocean Features
“The role that submesoscale features play in ocean dynamics is what makes them important,” explained Matthew Archer, an oceanographer at NASA’s Jet Propulsion Laboratory in Southern California. The SWOT satellite captures sea surface height at resolutions ten times finer than previous instruments, enabling researchers to identify and analyze eddies, internal waves, and currents too small to observe with earlier satellites or ship-based tools. These features generate vertical currents that move heat between the deep ocean and the surface, influencing how heat escapes into the atmosphere. Archer adds that such vertical circulation can actually bring deep ocean heat upward, which has direct consequences for atmospheric warming and climate regulation.
The satellite’s ability to detect these submesoscale structures across the Indian, Atlantic, and Pacific Oceans—as well as the Mediterranean Sea—has led to new insights about how marine ecosystems receive essential nutrients from below. These upward nutrient fluxes support surface food webs much like a constant supply chain, feeding marine life and sustaining ocean biodiversity. Prior to SWOT, understanding these dynamic processes was limited to localized measurements, but now global-scale observations allow for much broader, detailed analysis.
Advancing Ocean Modeling with High-resolution Data
“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,” said Nadya Vinogradova Shiffer, SWOT program scientist at NASA Headquarters in Washington. The rich data sets provided by SWOT enable oceanographers to calculate water pressure and current speeds by measuring water height and slopes. This foundational information on the forces driving fluid motion allows researchers to refine existing ocean circulation models, which previously focused on much larger-scale features.
The integration of SWOT data is already influencing models like NASA’s ECCO (Estimating the Circulation and Climate of the Ocean), helping to predict how energy, heat, and nutrients transfer within the ocean. Understanding these processes is critical for anticipating changes in marine ecosystems and the ocean-atmosphere interaction under shifting climate conditions. As SWOT data continues to feed into modeling efforts, it will enhance our capacity to forecast ocean behavior and its broader environmental impacts with greater precision.
Measuring Vertical Circulation and Energy Transport
One notable achievement of SWOT was detecting a submesoscale eddy off Japan in the Kuroshio Current, where researchers estimated vertical circulation speeds of 6 to 14 meters per day. Though modest, this vertical movement plays a significant role in transferring heat and nutrients between the ocean depths and surface. These measurements are now possible on a global scale thanks to SWOT’s advanced radar interferometer system, providing a new window into vertical ocean dynamics previously difficult to quantify.
The satellite also recorded an internal solitary wave in the Andaman Sea with energy at least twice that of a typical internal tide in the region, illustrating the variability and strength of these smaller-scale features. These insights allow scientists to better grasp the energy contained within ocean waves and their influence on mixing processes critical to ocean health and climate feedback loops.
