5aAO10. Surface wave parameters for the prediction of breaking waves and acoustic backscatter.

Session: Friday Morning, December 6

Time: 10:45

Author: Jeffrey L. Hanson
Location: Johns Hopkins Univ., Appl. Phys. Lab., Laurel, MD 20723
Author: Michael D. Mandelberg
Location: Johns Hopkins Univ., Appl. Phys. Lab., Laurel, MD 20723


Results from the acoustic surface reverberation experiment (ASREX) and critical sea test 7 (CST-7 phase 2) are examined to determine if surface wave parameters can be used to augment wind speed in air--sea process models. The wave parameters are extracted from directional wave spectra using a fully automated spectral partitioning approach. Isolated directional wind--sea spectra provide the basis for estimating the total rate of energy dissipation by breaking waves. The method employs Phillips' equilibrium range theory and extends Felizardo and Melville's recent work obtaining wave dissipation estimates from one-dimensional wave spectra. Preliminary results are encouraging; wave dissipation reduces the scatter in whitecap fraction observations by several orders of magnitude when wind speed is replaced with wave dissipation as the independent variable in the standard power-law model for whitecap fraction. It will be demonstrated that the success of this approach is partially attributed to a wind history bias that is automatically compensated for in the wave parameters. Results of similar on-going investigations using an extensive ambient noise and surface scatter observation set, collected during ASREX by the University of Miami, will also be discussed. [Work supported by ONR Code 32OA.]

ASA 132nd meeting - Hawaii, December 1996