Huge waves that struck Reunion Island and coastlines across Indonesia earlier this month all originated from the same storm that occurred south of Cape Town, South Africa, and were tracked across the entire Indian Ocean for some 10,000 kilometres over a nine-day period by ESA’s Envisat satellite.
Waves reaching up to 11 metres devastated France’s Reunion Island in the Indian Ocean when it slammed into the southern port of Saint Pierre on 12 May. Six days later waves created from the same storm measuring as high as 7 metres began crashing into Indonesia coastlines from Sumatra to Bali, killing at least one person and causing some 1200 people to flee their homes.
“The extreme swell systems originated from the same storm, which moved rapidly and had two main strong wind periods,” Dr Bertrand Chapron said. “As illustrated in the animation, the resulting waves were organised into two main swell systems that followed each other across the entire Indian Ocean, hitting Reunion Island, Mauritius, Australia and Indonesia.”
Storms are capable of generating waves of different wavelengths that travel in several directions upon leaving the storm system, with the longest wavelengths travelling the fastest. As these waves cross open seas, they can accumulate energy at precise locations and become very dangerous for marine safety.
In addition, wave systems slow down as they approach the coastline, and individual waves increase to reach at least two times the mean average of their initial wave height. For instance, a 5-metre significant wave height system can hit the coast with the height of 10 metres.
The radar satellite tech used in this ESA project is pretty trick. Interesting read – and follow the links at the end of the article.
SURFs UP….YAhooooo..
I’ve heard stories about “rogue” waves that come out of the blue, but here’s a good pic of one:
http://www.naval.com/heavy-seas/3/burin.jpg
This ship had a bad day. Mark my have an anecdote about these things, being ex-CG. I can’t imagine facing a 30 ft. wave in a 55 foot fishin’ boat,
adios, muchachos.
Rogue waves are one or two gigantic waves on the order of 50-100 ft. in height that originate out of a storm wave pattern of 25-30 foot waves. The few rogue waves generated out of 30 ft. seas are explained by chaos theory. I’ve heard it explained several times and it’s still difficult to comprehend. Waves in the 30 ft. category can be explained solely as a function of wind speed and fetch, while rogue waves are, as yet, unpredictable.
A lot of bulk cargo carriers go AWOL around the Cape of Good Hope. My dad once saw a bulk carrier sink in the North Sea during WWII and said it went down like a brick. If you blinked, you would miss seeing it.
Actually, Chris, you don’t need chaos theory or anything like it for rogue waves. The same folks at ESA + NOAA have done some fine tracking of so-called rogue waves, as well.
True, there isn’t as much known about them as other aspects of marine phenomena, surface and sub-surface; but, the past few years have seen a great deal of understanding just from getting round to looking, watching, recording.
The saddest bit is that Uncle Sugar is begging off on maintaining and continuing our share of satellite meteorology. Not part of the War On Terror, y’know.
Rogue waves are now spotted by satellite (just checking the height of the oceantops via laser), and tracked with the same method. The explanations I’ve seen have also involved chaos theory. They are certainly real, and I’m not even sure they require a 25-30ft wave to trigger one although it would make it more likely.
This interested me so much, I managed to get some research done due to being clouded out again. This most interesting and simple article shows how rogue waves could occur due to natural wave interference, without Schroedinger’s equation or chaos theory needed to explain them.
Some nice photos and animated graphs too, if anyone is intrigued.
http://www.math.uio.no/~karstent/waves/index_en.html