Case study of the transformation of swells propagating into Sendai Bay

Yongliang Wei, Hiroshi Kawamura

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


A high-resolution two-dimensional map of swell wavelength and propagating direction was retrieved from a phased array type L-band synthetic aperture radar scene observed on 24 September 2006 over Sendai Bay in the Tohoku region of Japan. Features of the wavelength map were compared with a wavelength map calculated from in situ measurements of the swell period using infinitesimal amplitude surface wave theory. The maps corresponded well in most areas, although large differences appeared in the near-shore area (area I) and an area of complicated bottom topography (area II). Because the spatial resolution of swell parameters was too coarse to investigate the surface waves in area I, wavelet transform (WT) was applied along a swell ray to improve the spatial resolution. In the resulting WT wavelength map, the large difference in area I disappeared. For area II, perturbation theory was introduced for surface waves propagating obliquely on a gentle slope. The large wavelength difference in area II was well explained by the second-order solution of perturbation theory.

Original languageEnglish
Pages (from-to)163-172
Number of pages10
JournalJournal of Oceanography
Issue number1
Publication statusPublished - 2012 Feb


  • Bottom slope
  • High-resolution swell map
  • Infinitesimal amplitude surface wave theory
  • Perturbation theory
  • Wavelet transform

ASJC Scopus subject areas

  • Oceanography


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