A statistical analysis of rogue waves in the southern North Sea

Abstract

A new wave dataset from the southern North Sea covering the period 2011–2016 and composed of wave buoy and radar measurements sampling the sea surface height at frequencies between 1.28–4 Hz was quality controlled and scanned for the presence of rogue waves. Here rogue waves refer to waves whose height exceeds twice the significant wave height. Rogue wave frequencies were analysed, compared to Rayleigh and Forristall distributions, and spatial, seasonal and long-term variability was assessed. Rogue wave frequency appeared to be relatively constant over the course of the year and uncorrelated among the different measurement sites. While data from buoys basically correspond with expectations from the Forristall distribution, radar measurement showed some deviations in the upper tail pointing towards higher rogue wave frequencies. Number of data available in the upper tail is, however, still limited to allow a robust assessment. Some indications were found that the distribution of waves in samples with and without rogue waves were different in a statistical sense. However, differences were small and deemed not to be relevant as attempts to use them as a criterion for rogue wave detection were not successful in Monte Carlo experiments based on the available data.