Tracking the attenuation and nonbreaking dissipation of swells using altimeters

Type Article
Date 2016-02
Language English
Author(s) Jiang Haoyu1, 2, Stopa Justin2, Wang He2, 3, Husson Romain4, Mouche Alexis2, Chapron Bertrand2, Chen Ge1
Affiliation(s) 1 : Ocean Univ China, Qingdao Collaborat Innovat Ctr Marine Sci & Techn, Coll Informat Sci & Engn, Qingdao, Peoples R China.
2 : IFREMER, Ctr Brest, Lab Oceanog Spatiale, Plouzane, France.
3 : State Ocean Adm, Natl Ocean Technol Ctr, Tianjin, Peoples R China.
4 : Collecte Localisat Satellites, Plouzane, France.
Source Journal Of Geophysical Research-oceans (2169-9275) (Amer Geophysical Union), 2016-02 , Vol. 121 , N. 2 , P. 1446-1458
DOI 10.1002/2015JC011536
WOS© Times Cited 4
Keyword(s) altimeter, swell dissipation, swell tracking
Abstract A method for systematically tracking swells across oceanic basins is developed by taking advantage of high-quality data from space-borne altimeters and wave model output. The evolution of swells is observed over large distances based on 202 swell events with periods ranging from 12 to 18 s. An empirical attenuation rate of swell energy of about 4 × 10−7 m−1 is estimated using these observations, and the nonbreaking energy dissipation rates of swells far away from their generating areas are also estimated using a point source model. The resulting acceptance range of nonbreaking dissipation rates is −2.5 to 5.0 × 10−7 m−1, which corresponds to a dissipation e-folding scales of at least 2000 km for steep swells, to almost infinite for small-amplitude swells. These resulting rates are consistent with previous studies using in-situ and synthetic aperture radar (SAR) observations. The frequency dispersion and angular spreading effects during swell propagation are discussed by comparing the results with other studies, demonstrating that they are the two dominant processes for swell height attenuation, especially in the near field. The resulting dissipation rates from these observations can be used as a reference for ocean engineering and wave modeling, and for related studies such as air-sea and wind-wave-turbulence interactions.
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