A New Solution for the Return Period of a Sea Storm in Which the Largest Wave Height Exceeds a Fixed Threshold

A new analytical solution for the return period of a sea storm in which the largest wave height exceeds a fixed threshold is obtained, by applying the Boccotti’s Equivalent Triangular Storm (ETS) model. An expression is then given for the probability that a wave, which is both higher than a fixed threshold and the highest of its own storm, will occur during a sea storm with a given intensity (the storm intensity being the maximum significant wave height during the storm). In the applications it is shown that the new solution has a simpler form than the Boccotti’s original one (two integrals to solve numerically, compared with the four integrals of the Boccotti’s solution), and that they give identical results. Finally it is achieved that the extreme waves of given height H, with large probability will occur in a sea storm with maximum significant wave height Hs max close to 0.5H.