Abstract
A multifrequency acoustical-backscatter technique is described for determining the size distribution of bubbles with radii between 8 and 130 µm. The method makes use of the resonance in the microbubbles and operates at six frequencies ranging from 28 to 400 kHz. It has the advantage that vertical profiles of the bubble-size distribution can be obtained for extended periods without need for in situ instrumentation. Algorithms have been developed for real-time calculation, including correction for wave orbital displacement, bubble attenuation of the transmitted pulse, and other effects.