British scientists have discovered waves that flow deep in the Pacific Ocean. Using ocean-going robots they detected the waves flowing eastwards almost a mile deep.
Scientists identify origins of freak waves
The waves – known as Kelvin waves – are much larger, longer and slower than waves seen at the beach and are triggered by changes in the weather patterns above the tropical ocean.
|A man watches huge waves at Great Yarmouth
They were known to occur on or near the ocean’s surface but the scientists were surprised to find them in the deep ocean.
Prof Karen Heywood, an oceanographer at the University of East Anglia (UEA) and co-author of the research, said: "We were both surprised and delighted.
"We expected to find something at about 50m because satellite imagery indicated it was there but we were really excited when we got a result at 1,500 metres. It opens up the possibility that there may be more waves even deeper down."
Dr Adrian Matthews, a meteorologist in UEA’s School of Environmental Sciences and lead author of the new research, said: "Everyone thought that there would be nothing to see below about 200m.
"Much to our delight, however, we found that even at 1,500 metres there was a regular wave in temperature and saltiness, moving east every couple of months across the tropical Pacific."
The finding may be important for predicting climate change and for weather forecasting in the tropics.
The scientists believe the ocean waves are caused by the climatic variation known as the Madden Julian Oscillation (MJO) – which may in turn be a trigger for an El Nino – the ocean-atmosphere system in the tropical Pacific which influences weather worldwide.
"The Madden Julian Oscillation is one of the main sources of changes in weather and climate in the tropics, said Dr Matthews.
"It makes a big difference to people’s lives in places like Indonesia and India.
One week there will be lots of rain, and then a few weeks later it’s abnormally dry, then a few weeks later it’s back to rain again."
The scientific team made the discovery using free-floating robots known as Argo floats. These operate at around 1km depth but surface every 10 days, measuring temperature and salinity as they go. At the surface they transmit their data via satellite before descending back to the deep ocean.
Prof Heywood said: "In the last couple of years there has been a revolution in the way we can find out about what is going on in the ocean.
"Oceanographers all over the world got together to deploy an armada of 3000 Argo floats and as a result there have been more observations of the ocean climate in the last few years than all the measurements put together since oceanography began as a science about 100 years ago."