Acoustical measurements of bubble production by spilling breakers

The surface bubble spectral density of newly created bubbles has been measured under spilling breakers in a laboratory facility. This has been accomplished acoustically by passively identifying the radius, position, and time of creation of several hundred individual bubbles as their shock‐excited pulsations radiate damped spherical waves of sound. The measured bubble spectrum ranges from radius 50 μm to 7.4 mm with a peak of 6 bubbles per square meter in a 1‐μs‐radius increment at radius 150 μs. The rate of bubble production has an exponential fall‐off with time and 97% of the bubbles are produced in the first 500 ms after the breaker passes. The results supplement recent ocean data for low sea states.