On the Interpretation of Fetch-Limited Wave Spectra as Measured by an Airborne Sea-Swell Recorder
Abstract
A section of sea surface that had been subjected to a constant, offshore wind was profiled using an airborne radar wave profiler. The profiles extended from the coast out a distance of 190 nautical miles. From this data estimates of the spectrum of encounter of the sea surface were obtained for a number of different fetch lengths. By solving a singular Fredholm integral equation of the first kind, it was possible to retrieve the true wave spectrum as a function of fetch length. Spectral growth curves were then obtained and analyzed in light of recent theories of wave generation. The data lend support to the previous conclusions of Snyder and Cox (1966) regarding two recent theories of wave generation. Specifically, the data are consistent with the 'resonance' theory of wave growth (Phillips, 1957), but at the same time suggests that wave growth through an instability mechanism (Miles, 1957) is yet to be understood. One of the most significant results of this study was that higher frequency waves grow past or 'overshoot' their eventual equilibrium energy value. After 'overshooting' they then rapidly decay back to an equilibrium range.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1967
- Accession Number
- AD0824468
Entities
People
- J. C. Wilkerson
- T. P. Barnett
Organizations
- Naval Oceanographic Office