A laser-equipped ocean platform has uncovered two rival wind-wave energy exchanges, each shaping the sea's surface in surprising ways.
The discovery offers a clearer window into how the atmosphere and ocean share heat, gases, and momentum.
Laser Mapping Exposes Hidden Air-Sea Dance
A research collaboration led by Dr. Marc Buckley of the Hereon Institute of Coastal Ocean Dynamics has developed a powerful new way to visualize the interaction between air and sea. Working aboard the FLIP (Floating Instrument Platform) in the Pacific Ocean, the team used a custom-built laser measurement system to record highly detailed images of airflow occurring just millimeters to one meter above the water's surface. This approach allowed them to identify two distinct wind-wave coupling processes that occur at the same time but behave in very different ways.
Short waves, roughly one meter long, travel more slowly than the wind above them. As the wind strikes these crests, it separates, creating a pressure difference that transfers energy directly into the wave. In contrast, long waves, which can stretch up to 100 meters, actually move faster than the wind. Their motion produces its own unique airflow patterns. Both of these mechanisms take place simultaneously in different parts of the wave field, an insight that could significantly improve the accuracy of atmospheric and ocean circulation models.
Airflow Insights Supercharge Climate Models
The exchange of energy, heat, and greenhouse gases between the ocean and atmosphere is a central driver of global climate and weather systems. Although scientists have long recognized the importance of these interactions, the fine-scale physical mechanisms behind them have remained largely unexplored. The research team aims to enhance their system so that it can also track movement beneath the water's surface with greater precision.
"Until now, no one has measured the airflow this close to the ocean surface, let alone mapped the mechanisms of energy exchange at such a fine scale," says lead author Buckley. "Our observations shed light on a physical frontier. This will enable us to advance the theoretical framework and develop more accurate descriptions of air-sea exchange processes, which have so far been only partially understood."
PIV Laser Captures Ocean Surface in 3D
The imagery is based on a laser that passes through both air and water: the green beam hits water droplets introduced into the air -- similar to mist illuminated by sunlight. These droplets follow the motion of the airflow, scatter the laser light, and make even the smallest movements in the air visible. At the same time, the laser penetrates the water surface. At the wind-driven surface, the light is refracted -- revealing the structure of the water surface.
This combination allows both the air and water sides to be visualized. The method is based on Particle Image Velocimetry (PIV), an established technique in fluid dynamics. PIV provides precise information about flow structure and wind speeds. This marks the first time the technique has been used over the open ocean.
Reference: "Direct observations of airflow separation over ocean surface waves" by Marc P. Buckley, Jochen Horstmann, Ivan Savelyev and Jeff R. Carpenter, 31 June 2025, Nature Communications.
DOI: 10.1038/s41467-025-61133-1