A global climatology of the wave age parameter, based on the ERA-40 wave reanalysis, is presented in the present study. The annual and seasonal climatological patterns of the wave age are shown, confirming, in line with previous studies, the global predominance of swell waves in the World Ocean. The interannual variability of the wave age fields are studied by means of an EOF (empirical orthogonal function) analysis. The leading modes of variability of the wave age demonstrate that the areas of higher explained variability (the centers of action) occur mostly along the equator, coinciding with the so called swell pools, where long waves coincide with light winds.
A Semedo, A Rutgersson, A Sterl, K Sušelj. The global wave age climate
Marine Engineering and Technology, 2012, Taylor and Francis Group