An experiment to measure low-frequency acoustic backscatter from the ocean wave surface: The Acoustic Surface Reverberation EXperiment, ASREX.

摘要

The design and analysis of data from a surface reverberation experiment that was performed in the North Atlantic Ocean during the winter of 1993-94 is presented. Observations of acoustic backscatter from the ocean surface were made from a moored vertical array at frequencies ranging from 100 to 800 Hz at twelve minute intervals during a three month period. Other investigators (from Scripps Institution of Oceanography, Woods Hole Oceanographic Institution, and the Institute of Ocean Science in British Columbia, Canada) simultaneously made measurements of a variety of environmental parameters, including wind speed and direction, wave spectra, air and sea temperature and current fields, and the presence and nature of bubble clouds were observed with high frequency side scan sonars and devices that detected anomalies in the near surface sound speed. Analysis of the 400 and 800 Hz data is presented here. Comparisons with results from other recent observations (P. M. Ogden and F. T. Erskine, J. Acoust. Soc. Am. 95(2), February, 1994) and the Chapman-Harris empirical formula (R. P. Chapman and J. H. Harris, J. Acoust. Soc. Am. 34(10), October, 1962) are made. Multivariate analysis of backscattering strength as a function of ambient noise and various other environmental parameters is performed and discussed. Wind speed is seen to be the dominant variable for both frequencies analyzed, but does not account for all the variance in the power spectra of the backscattered energy. Wave parameters become increasingly important for the 400 Hz data. There are also indications in the data that ambient noise is a strong indicator of scattering strength.