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Wavelength of ocean waves and surf beat at duck from array measurements

DRS at CSIR-National Institute of Oceanography

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Title Wavelength of ocean waves and surf beat at duck from array measurements
 
Creator Fernandes, A.A.
Menon, H.B.
Sarma, Y.V.B.
Jog, P.D.
Almeida, A.M.
 
Subject surface water waves
surf beats
directional spectra
computation
wave direction
wave height
wave energy
 
Description Wavelength of ocean waves and surf beat (infra gravity waves) has for the first time been computed as a function of frequency from different combinations of non-collinear 3-gauge arrays. Data at the 15-gauge polygonal array at 8 m depth at Duck, North Carolina, USA, has been used. The method used is an extension of the 3-gauge method of Esteva 1976 and 1977 for computing wave direction. Wavelength was also computed using the Singular Value Decomposition (SVD) method of Herbers et al. 1995 from (1) K sub(rms) and (2) K sub(x), K sub(y). The wavelength computed from the array measurements, using both the 3-gauge as well as the SVD (K sub(x), K sub(y)) method, is nearly identical to the wavelength predicted by the well known dispersion relation for ocean waves (DROW), viz., (2 pi f) sup(2) = kg tanh Kd, in the ocean wave regime (T is less than or equal to 11.64s spectral period); and is approximately thrice the predicted value in the surf beat regime ( T is more than or equal to 32.00 s). The implication of wavelength of surf beat at Duck being much larger than that predicted by DRDO, is that methods for determining the directional spectrum which use DROW can erroneously indicate a surf beat direction much close (approx.. 30 degrees closer) to the shore normal than it actually is in the field. For example the variational method of Herbers et at. 1995 and the 2-gauge array method of Borgman 1974 are unfortunately both tained with this error due to use of DROW
 
Date 2009-01-07T11:01:36Z
2009-01-07T11:01:36Z
2001
 
Type Conference Article
 
Identifier Ocean wave measurement and analysis. Proceedings of the Fourth International Symposium Waves 2001, September 2-6, 2001, San Francisco, California. Vol. 2, Ed by: Edge, B.L.; Hemsley, J.M. 1-10p.
http://drs.nio.org/drs/handle/2264/1604
 
Language en
 
Rights Copyright [2001]. All efforts have been made to respect the copyright to the best of our knowledge. Inadvertent omissions, if brought to our notice, stand for correction and withdrawal of document from this repository.
 
Publisher American Society of Civil Engineers, Virginia, USA