Extreme wave heights

Image of the Month - June 2011

Extreme wave height statistics for a 20-year return time depending on the season. Top, Northern hemisphere winter, with the highest waves at about 17 m at high latitude; in the Southern hemisphere winter (bottom), the equivalent latitudes also show high waves, even if slightly less so. (Credits IH Cantabria - Universidad de Cantabria)

 
Altimetry not only provides with sea surface height, but also with wave heights. With now nearly twenty years of data available, significant statistics on extreme wave heights are now possible, as well as correlations between wave heights and ocean-atmosphere oscillations (ENSO, NAO...).
A model enables to estimate the distribution of the extreme wave heights in space and time from the altimetry data series. Extreme wave height corresponding to a 20-year return period are thus estimated. They depend, of course, of the season. They also depend on the latitude, with the highest values in the North Atlantic and Pacific (with heights up to 17 m) in the boreal Winter, and in the Southern Ocean (in the austral Winter).

Altimetry satellites will continue providing such information in the coming years, with several missions planned. Moreover, the CFOSat  mission will test new sensor concepts dedicated to such applications.

Influence of the Artic Oscillation (left) and of ENSO (NINO3 index) on wave heights. yellow-red means that the index is positively correlated to wave heights, and strongly so (up to 60 cm of wave height per unit of the index); green means that when the index is negative, waves are higher. (Credits IH Cantabria - Universidad de Cantabria)

See also:

References:

  • Izaguirre, C., F. J. Méndez, M. Menéndez, and I. J. Losada (2011), Global extreme wave height variability based on satellite data, Geophys. Res. Lett., 38, L10607, doi:10.1029/2011GL047302.