Significant wave height

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Significant wave height, also known as SWH, or Hs, is the average height (trough to crest) of the one-third largest waves. A well developed significant wave is approximately equal to Hm0, defined as four times the standard deviation of the instantaneous displacement from the mean sea level. The American Meteorological Society defines SWH as Hm0[1].

The original definition resulted from work by the oceanographer Walter Munk during World War II.[2][3] The significant wave height was intended to mathematically express the height estimated by a "trained observer". It is commonly used as a measure of the height of ocean waves.

A related notation, Hn, where n is a percentage or a fraction, describes the wave height of the nth percent highest waves.[4] Hn is used to estimate the average maximum wave size (H0.99) and for certain other analysis. To eliminate any confusion with this Hn notation, the notation H1/3 is used by the IMO, the U.S. Code of Federal Regulations, most classification societies, as well as many scientific papers. Hs is a special case of Hn.

Other statistical measures of the wave height are also widely used. The RMS wave height, which is defined as square root of the average of the squares of all wave heights, is approximately equal to Hs divided by 1.4.

According to the Irish Marine Institute, 'at midnight on 9/12/2007 a record significant wave height was recorded of 17.2m at with a period of 14 seconds'.[5]

[edit] See also

[edit] References

  1. ^ Significant wave height. Glossary of Meteorology. Retrieved on 2007-06-30.
  2. ^ Denny, M.W. (1988). Biology and the Mechanics of Wave-swept Shores. Princeton, New Jersey: Princeton University Press. ISBN 0691084874. 
  3. ^ Munk, W.H. (1944). Proposed uniform procedure for observing waves and interpreting instrument records. La Jolla, California: Wave Project at the Scripps Institute of Oceanography. 
  4. ^ Sorenson, Robert M. (1993). Basic Wave Mechanics: For Coastal and Ocean Engineers. New York, NY: John Wiley & Sons. ISBN 0471551651. 
  5. ^ web site of the Irish Marine Institute. Retrieved on 2008-01-13.

[edit] External links

Finnish Institute of Marine Research: Significant wave height

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