LONG WAVES IN AND NEAR THE SURF ZONE.
Abstract
Four sets of field measurements were made of swell in and just seaward of the surf zone off a uniform sandy beach. Power spectra computed for both the pre-breakers and the foam lines revealed long waves associated with the swell having peak periods centered at approximately 80 seconds. Long wave records were produced by filtering out the ordinary swell through computing running means of the pre-breaker and foam-line records. Computer comparison of the long-wave records at the offshore and surf-zone sites for a given field run resulted in a time-correlation curve for various time lags between the records. Curves for all of the runs reveal that the long waves arrive from the open ocean, probably as forced waves travelling with swell groups, undergo reflection at the beach, and return back to sea as free waves. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1967
- Accession Number
- AD0824132
Entities
People
- John Ford Hopper
Organizations
- Naval Postgraduate School