Abstract: The air-sea interface is a very complex boundary, and those complexities have an especially strong influence on the transfer of gases between the atmosphere and the ocean. The bubbles formed by breaking waves are thought to have a significant effect on gas transfer, particularly for carbon dioxide and oxygen. However, our knowledge of the detailed processes responsible is very limited at higher wind speeds, when breaking waves, turbulence and complex flow patterns (like Langmuir circulation and Stokes drift) interact to create a highly inhomogeneous situation. Current parametrizations of these processes are empirical global averages, mostly based only on wind speed, and are not suitable for assessing more localised exchange. The recent “Bubble Exchange in the Labrador Sea” project was a large international experiment designed to address this gap by studying directly the mechanisms of gas transfer in the top few metres of the ocean. It took place in November and December 2023 in the central Labrador Sea, in conditions with wind speeds up to 30 m/s. We will present an outline of the bubble, dissolved gas, and flow data collected, and consider how this relatively small-scale physics could inform revised parametrizations of gas transfer.
Short Bio: Dr Helen Czerski is a physicist and oceanographer based at University College London. Her scientific research focuses on the physics of breaking waves and bubbles at the ocean surface. She has spent months working on research ships in the Antarctic, the Pacific, the North Atlantic and the Arctic, and is an experienced field scientist. She is also a writer and broadcaster, including as a regular presenter of radio and tv science programmes for the BBC since 2010. She currently co-hosts Rare Earth on BBC Radio 4.
Short Bio: Dr. Intesaaf Ashraf is an experimental fluid dynamicist whose current research focuses on bubble dynamics in the ocean surface layer, examining how wind, wave breaking, and turbulence shape bubble size distributions, void fractions, and air-sea gas exchange. He uses high-resolution oceanographic data, advanced image processing, and statistical analysis to understand bubble-mediated transport in dynamic marine environments. His past research spans a broad range of topics in unsteady fluid mechanics, including fluid-structure interaction, aeroelasticity in flapping wings, and bio-inspired locomotion, combining laboratory experiments, PIV, and CFD simulations to investigate flow-structure coupling in turbulent regimes