Measurements of bubbles, drops, and dry aerosol particles in laboratory experiments on spray generation by bubble bursting*

Bubbles entrained by breaking waves rise to the ocean surface, where they reside before bursting and releasing droplets into the atmosphere. The ejected aerosols affect the climate, motivating study of the controlling parameters behind bubble bursting at the ocean surface. To investigate the effect of salinity on spray production, experiments were conducted in a 50x50x60 cm³ bubbling tank filled with solutions of artificial seawater with salt concentrations ranging from 1.3 to 42 g/L. Combined measurements of bulk bubbles, surface bubbles, drops, and dry aerosol particles were made at each salinity level. Cases were run for bubbles rising in both quiescence and turbulent flow, where turbulence leads to bubble breakup in the bulk and a broad size distribution of bubbles rising to the surface. Bulk and surface bubbles were captured using planar shadowgraph techniques, while drops were imaged with an in-line holographic system and a shadowgraph technique with a telecentric lens. Dry particles were measured using a scanning mobility particle sizer. We discuss resulting distributions of sizes and volumes of the bubbles, drops, and particles and links between the different measurements and the production mechanisms.