Abstract:
Bubbles injected by breaking waves move under the influence of buoyancy, near-surface turbulence and Langmuir circulation and are subject to gas transfer across the bubble skin. In order to study these effects a resonator has been developed for in situ measurement of bubble size distributions and has been deployed with other instrumentation in the open ocean at wind speeds up to 18 m/s. The resonator differs from the Medwin design in its use of two identical reflector plates to form a 1/2(lambda) cavity immune to flow-induced or hydrostatic pressure fluctuations. Separate inversion of both sound speed and attenuation over a broad frequency range provides a useful consistency check on results. Measurements with a coherently operated array of self-contained resonators in drifting or moored configurations have yielded a database for detailed investigation of bubble size distributions. Turbulent diffusivity in the wave enhanced layer, vertical and horizontal velocity structure, and dissolved N[inf 2] and O[inf 2] were measured simultaneously with the bubble size distributions. Data are analyzed and interpreted with the aid of a two-dimensional model of the flow dynamics, incorporating representative turbulent diffusivity and advection and accounting for both primary gas constituents.