Near surface bubble, gas and flow measurements during the Bubble Exchange in the Labrador Sea (BELS) cruise – early results

The bubbles formed by breaking waves are thought to play an important role in increasing gas transfer across the atmosphere-ocean surface during high wind conditions (>15 m/s).  However, real world data on near-surface bubbles with sufficient resolution in space, time and bubble size to understand exactly how the transfer mechanisms work is rare. In addition, there are almost no data showing the relationship between bubble size distributions and the local flow and gas saturation conditions, although data from the HiWinGS cruise suggests that these structures could be very important for gas transfer. The BELS project data was collected during five weeks in November/December 2023, and includes tracer-based gas flux measurements, physical oceanography, and ocean chemistry.  Hourly averaged wind speeds were 5-30 m/s, with maximum significant wave height of 11 m.  Here, we will present early results from the part of the project monitoring near-surface bubbles and their relationship to flow patterns and dissolved gas concentrations in the top five metres of the ocean. Data will be presented from a free-floating buoy carrying specialised bubble cameras at 1m and 3m, ADCPs and oxygen optodes. We will show measured bubble size distributions, and the spatial relationship of these bubbles to Langmuir circulation patterns and dissolved oxygen concentrations. We will also present an early analysis of the relationships between gas carried by both the water itself and the bubbles, and how this relates to the advection of these two gas reservoirs in the top few metres of the ocean.