Bimodal Directional Distribution of the Second Kind: Resonant Propagation of Wind-Generated Ocean Waves
Abstract
Over the last several decades, it has been accepted that under steady forcing, wind-generated waves travel in the direction of wind. Last year, we presented two-dimensional (2D) spectral analysis of 3D ocean wave topography at equilibrium stage. The results demonstrate unequivocally a robust bimodal directionality in wave components shorter than the dominant wavelength. The generation mechanism of the bimodality is clarified to be nonlinear wave-wave interaction. Continued investigation reveals a second kind of bimodal directional distribution produced by resonant propagation of waves with the forcing wind field. In this situation, the dominant waves in a young sea align in oblique angles with the wind direction to maintain propagation resonance for a more efficient air-sea momentum transfer. As a result, two symmetric wave systems straddle the wind vector. The results from these analyses will revise our fundamental understanding of the physics of wind-wave generation and the forcing functions governing the dynamics of ocean waves. The implications of these directional observations on remote sensing (directional characteristics of ocean surface roughness) and air-sea interaction (directional properties of mass, momentum, and energy transfers) are significant.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2001
- Accession Number
- ADA596946
Entities
People
- D. W. Wang
- J. M. Kaihatu
- J. Yungel
- P. A. Hwang
- R. N. Swift
- W. B. Krabill
- W. E. . Rogers
Organizations
- Naval Meteorology and Oceanography Command