Bubble Exchange in the Labrador Sea - 2023

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The focus of this project is to understand how bubbles formed by breaking waves at sea can help the ocean breathe. The ocean and atmosphere are connected at the ocean surface, and huge quantities of gases like carbon dioxide and oxygen continuously cross that surface in both directions. This is an important process because it helps regulate the amount of carbon and oxygen in both atmosphere and ocean; the ocean has taken up around 25% of the excess carbon that humans have added to the atmosphere by burning fossil fuels. Understanding this breathing process for different gases is important for climate models and also to understand the influence of these gases on ocean life.When gases are transferred from the atmosphere to the ocean, they may remain dissolved near the ocean surface, or in some parts of the global ocean they may be transported further downwards and then won't return to the surface for many centuries. We know that storms at sea speed up the air-sea gas exchange across the surface, but we are not yet able to predict exactly how much gas will be exchanged at the highest wind speeds. We think that the critical missing link in our understanding is the bubbles formed by breaking waves, which help to push gas into the ocean, especially in big storms. However, we don't know exactly how many bubbles are formed in the highest winds, where they go once they're underwater and when the gas is transferred to the ocean. We also suspect that the complexities of wind and waves, and complicated water flow patterns near the ocean surface may have a strong influence on the outcome. The aim of this project is to measure the bubble processes in the top few metres of the ocean during large storms in order to understand how bubbles contribute to gas exchange.During this project, we will join an international collaboration on a German research ship in the North Atlantic. Our colleagues will be measuring gas exchange, meteorology and the processes occurring in the top few hundred metres of the ocean. We will measure the bubbles, the dissolved gas concentrations and the flow patterns in the top eight metres of the ocean. Custom-built bubble cameras, gas sensors and acoustic devices to measure water flow will be mounted on a long spar buoy which can float by itself for several days in large storms. This will enable us to follow how the bubbles move, when they give up their gas to the ocean, and how that gas moves around near the ocean surface. This data will be used to understand the mechanisms of bubble-mediated gas exchange, and will be used to test and develop computational models built by our colleagues. The advantage of this project is that between the collaborators, we can watch all the critical processes at different size and time scales simultaneously, so we will be able to learn how they influence each other. The outcome will be better understanding of why bubbles matter, so that we can improve our predictions of gas transfer for all gases.