How the oceans breathe: Field measurements of bubble-mediated gas exchange processes in the Labrador Sea

The Labrador Sea in the northwest Atlantic presents conditions that favor the co-existence of deep convection and Langmuir circulations that facilitate deep overturning of gases and bubbles resulting from breaking waves on the air-sea interface. The rates and mechanisms of gas exchange in strongly convective conditions are still poorly known due to the lack of detailed measurements in these conditions and incomplete knowledge of bubble processes in gas transfer. Here we present observational results from the Bubble Exchange in the Labrador Sea (BELS) experiment conducted in December 2023, where air-sea invasion rates of O2/N2 are measured using autonomous underwater vehicles (AUVs) equipped with dissolved gas sensors and gas tension sensors. We also present concurrent measurements of bubbles and currents using forward-looking sonars and acoustic Doppler current profilers (ADCP), which enables novel spatiotemporal imaging of bubble volume fractions, sizes, and distributions, as well as measurements of bubble generation from wave breaking and their interactions with Langmuir circulations and convective turbulence. These data sets are used to estimate bubble-mediated gas transfer rates using 1D and 3D budgeting approaches. The goal is to incorporate the model into a more accurate parametrization of air-sea gas exchange to reduce uncertainties in global climate models.