Sunday, November 6, 2011

Rogue Waves

What defines a rogue wave?

Rogue waves are spontaneous and unexpected waves. They are usually large and can quite often be extreme and even killer. They may not always be the biggest waves but are abnormal and large for the state of the sea in a particular area. A rogue wave is twice the significant wave height (SWH). Their occurrence is usually in deep water from which a number of factors, combined together, will cause a rogue wave to occur. These factors include strong winds and fast currents.

A rogue wave is not to be confused with a tsunami which occurs from an earthquake within the ocean bed. They are simply a natural phenomenon that occurs in the ocean and are a threat to all ships, vessels and even large cruise liners. Satellite images have shown the ferociousness of a rogue wave. Often rogue waves have been referred to as a myth but the Draupner wave is a significant wave that implied they are real.

History

Storm waves in mid-ocean can often reach between 23 feet to 49 feet. Yet there have been reports of mid-ocean waves in calm waters that have reached around 98 feet hight. Appearing with no warning and on a clear, sunny day.

What was the Draupner wave?

The Draupner wave occurred on New Years Eve off the North Coast near Norway. It occurred at what is known as the Draupner platform and measuring instruments detected it. This particular rogue wave was around 39 feet high. An Engineer, Paul Taylor, measured the Draupner wave as a one in 200,000 wave.

What are the causes?

There is much conflict surrounding the cause of rogue waves. Rogue waves are still an area that oceanographers don't know a great deal about. There is still much research about these waves and it is hard to define due to the randomness of their occurrence. They also occur in different places. One of the highest risk areas is near Cape Agulhas, off the South tip of Africa. It is thought that because the current is warm here and strong and, due to the direction of the wind, rogue waves are more likely to occur.

Many people have claimed that rogue waves are in fact, all part of the norm. Oceanographers have used a system based on maths called the Linear Model in order to predict the height of a wave. It is based on probability. So the idea of the theory is that a wave would not 'normally' be higher than 15 metres, but it could.

Meteorologists have also been involved in trying to understand the cause and probability of a rogue wave. Using the European Space Agency (ES) and the European Remote Sensing Satellite (ESR) they have tried to predict where these waves come from, why and when they might occur again. One of the theories is that of the 'Schrodinger Equation'. This is a Quantum Physics based theory which implies that waves steal energy from other waves. This is what causes some waves to remain small as their energy has been stolen and others to sap the energy from others and grow to form a rogue wave.

All in all, it just adds to the mystery of the ocean. It is another thing that sailors need to understand and be aware of. The ocean should be respected at all times and an effort should be made in order to understand it better.


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