Wave characteristics
Wave characteristics

In fluid dynamics, the wave height of a surface wave is the difference between the elevations of a crest and a neighboring trough.[1] Wave height is a term used by mariners, as well as in coastal, ocean and naval engineering.

At sea, the term significant wave height is used as a means to introduce a well-defined and standardized statistic to denote the characteristic height of the random waves in a sea state, including wind sea and swell. It is defined in such a way that it more or less corresponds to what a mariner observes when estimating visually the average wave height.


Depending on context, wave height may be defined in different ways:

Significant wave height

In physical oceanography, the significant wave height (SWH, HTSGW[3] or Hs) is defined traditionally as the mean wave height (trough to crest) of the highest third of the waves (H1/3). Nowadays it is usually defined as four times the standard deviation of the surface elevation – or equivalently as four times the square root of the zeroth-order moment (area) of the wave spectrum.[4] The symbol Hm0 is usually used for that latter definition. The significant wave height (Hs) may thus refer to Hm0 or H1/3; the difference in magnitude between the two definitions is only a few percent.

SWH is used to characterize sea state, including winds and swell.

RMS wave height

Another wave-height statistic in common usage is the root-mean-square (or RMS) wave height Hrms, defined as:[2]

with Hm again denoting the individual wave heights in a certain time series.

See also


  1. ^ a b c Kinsman (1984, p. 38)
  2. ^ a b Holthuijsen (2007, pp. 24–28)
  3. ^ "About earth :: A global map of wind, weather, and ocean conditions".
  4. ^ Holthuijsen, Leo H. (2007). Waves in Oceanic And Coastal Waters. Cambridge University Press. p. 70. ISBN 978-0-521-86028-4.


  • Holthuijsen, Leo H. (2007), Waves in Oceanic and Coastal Waters, Cambridge University Press, ISBN 978-0-521-86028-4, 387 pages.
  • Kinsman, Blair (1984), Wind waves: their generation and propagation on the ocean surface, Dover Publications, ISBN 0-486-49511-6, 704 pages.
  • Phillips, Owen M. (1977), The dynamics of the upper ocean (2nd ed.), Cambridge University Press, ISBN 0-521-29801-6, viii & 336 pages.