Measurements of excess attenuation from near-surface bubbles from the Shallow Water '06 experiment are reported. These are transmission measurements made over the frequency range 1-20 kHz, and they demonstrate a frequency, grazing angle, and wind speed dependence in attenuation. Data modeling points to bubble void fractions of order 10-6 in effect for wind speeds 10-13 ms. Simultaneous measures of wind speed made within 1.5 and 11 km of the open water experimental location differed by 2 ms in their respective 30 min average; this has cautionary implications for empirical models for bubble attenuation that are a strong function of wind speed.
ASJC Scopus subject areas
- Acoustics and Ultrasonics