Research investigating rogue wave trends could improve safety at sea and inform industry

Rogue waves can pose a danger to ships and offshore structures. They are unpredictable and are ocean surface waves larger than the surrounding sea that suddenly appear. There is a need for fast predictors and Alex Cattrell, PhD student is leading research at the University of Southampton to investigate this phenomenon. Research findings show that they are occurring less often, but are becoming more extreme.

Waves are defined as ‘rogue’ when they are more than double the significant wave height of the background sea state (the average height of the top third of the highest waves). From trough to peak, past viewings have put some at over 30 metres high. The most severe ones can damage or sink ships, wound or kill crew members and carry people off the shoreline and out to sea.

It is a globally significant issues for the shipping industry and rogue waves occur several times every day. Alex and a team of engineers and oceanographers from Southampton, together with researchers from the National Oceanography Centre, researched over 20 years of data (1994–2016) from 15 buoys, which provide surface data along the US western seaboard.

On average, the team found instances of rogue waves (across the two decade window) fell slightly, but that rogue wave size, relative to the background sea, increased by around one per cent year-on-year. Interestingly, rogue waves occur more often and increase in severity in the winter months and, happen with increasing frequency within calmer background seas.

Rogue waves have been known to fatally carry people out to sea at Point Reyes, Maverick’s beach and Arcata, in California and Depoe Bay, in Oregon along the western coast of the USA. In 2000, the US National Oceanic and Atmospheric Administration’s research vessel RV Ballena capsized off Point Conception, California, and in 2006, MV Westwood Pomona encountered a rogue wave off Port of Coos Bay, injuring one person and damaging the vessel.

Research supervisor, Professor Meric Srokosz, adds: “Ports along the west coast of America handle almost half of the country’s container trade and, together with shipping connected to the Californian oil industry, there is a high volume of tanker, cargo, fishing and passenger vessel activity in the region.

“Our research can help inform these industries and suggests that if data on rogue waves is to prove useful, geographical, seasonal and year-on-year variations need to be taken into account.”

Alex Cattrell and the team hope more work can be done using their research method in other parts of the world, adding to existing research sources, to better understand how, and predict when, these destructive forces may strike.