Scientists Crack the Code to Sharpen Satellite View of Ocean Eddies
A new method using a U.S. Navy ocean model strips away the "noise" of internal tides from satellite data, revealing small-scale eddies critical to understanding Earth's climate.
Ann Arbor, MI – Researchers at the University of Michigan have developed a powerful new technique that significantly improves the clarity of ocean observations made by the Surface Water and Ocean Topography (SWOT) satellite. By leveraging the U.S. Navy’s Hybrid Coordinate Ocean Model (HYCOM), the team can now predict and remove the signal of internal tides, which have long obscured satellite views of smaller ocean features.
The Problem: Ocean "Noise" Hiding Climate Clues
Internal tides are vertical movements of water generated when large-scale surface tides interact with seafloor features like ridges and mountains. These movements leave a subtle signature on the ocean surface, acting as "noise" that masks the smaller, critical signals of eddies measuring 5–10 kilometers in size.
Why It Matters:
These small eddies are vitally important for:
- Understanding the transport of heat and carbon in the ocean.
- Improving the accuracy of global weather forecasting models.
The Breakthrough: A 60% Improvement
The research team, led by former University of Michigan postdoctoral fellow Yadidya Badarvada (now at Florida State University), used HYCOM to estimate the sea-surface height signature of internal tides. They then compared these estimates with actual data from SWOT, a joint NASA and CNES mission launched in 2022.
The result is dramatic: The new approach accounts for 60% more of the internal tide signal than previous methods. This provides a far clearer and more accurate view of the small-scale eddies that SWOT was designed to observe.
A Two-Way Street: Navy Models and NASA Data
The study, published in Science Advances, highlights a productive feedback loop between defense and scientific institutions.
"The Navy forecast model improves NASA observations, and those observations in turn improve Navy predictions." — Yadidya Badarvada, lead author
Co-author Brian Arbic, a professor at the University of Michigan, emphasized the broader implications:
"This work demonstrates the use of Navy ocean forecast models to map tides at high accuracy, aiding the SWOT mission in obtaining clearer images of ocean features." He noted that this is a "great story of climate relevance," as internal waves significantly affect ocean circulation and biology.
Background and Funding
The integration of tidal data into HYCOM required decades of prior research. The project was funded by the Office of Naval Research, Naval Research Laboratory, NASA, and CNES.