Rogue waves

Project Rationale:

Rogue waves are ocean surface gravity waves whose waveheights are much larger than that expected given the background wave conditions (e.g. the first instrumentally recorded rogue wave was 25.6m in a background wavefield of ~12m significant waveheight). They commonly appear unexpectedly and can cause significant damage to ships and offshore installations. Recent research using an extensive data set of measurements from wave buoys (of around 1 billion waves) has shown that the probability of rogue waves occurring cannot be predicted from basic information on background wave conditions (Cattrell et al., 2018). More detailed examination of a subset of the buoy data, that spanned more than 10 years of observations, has revealed that rogue wave conditions can vary seasonally and spatially, also changing over the long-term (Cattrell et al., 2019). Unresolved questions from these studies are: how the directional properties of the rogue waves vary i.e. is there a preferred direction from which they appear at a given location? How is rogue wave occurrence related to the directional properties of the background wavefield and ocean surface currents? Can knowledge of these directional properties and background conditions help in determining the probability of occurrence of the rogue waves?

Methodology:

Previous studies (Cattrell et al., 2018, 2019) did not examine the directional properties of rogue waves nor those of the background wavefield. Using the same buoy data set, and any newly acquired observations, data on rogue waves will be re-extracted but now taking account of the directional information contained in the measurements. The resulting dataset will be analysed using a variety of standard statistical / mathematical methods (e.g. spectral analysis, multivariate regression) to examine the influence of directionality on the occurrence of rogue waves. The results obtained will be used to assess a variety of theoretical models that have been proposed for rogue wave generation and occurrence. In addition, it may be possible to exploit satellite data (from CFOSAT https://cfosat.cnes.fr/en/CFOSAT/index.htm) on wave directionality to examine the global distribution of rogue wave occurrence, by extrapolating results obtained from the analysis of the buoy data.

Training:

The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at the National Oceanography Centre, Southampton.

Specific training will include:
• computing and statistical methods required for the analysis of the buoy and rogue wave data
• basics of ocean surface gravity waves and rogue waves – theory and observations
• numerical model hindcasts and forecasts of ocean surface currents and waves