Wednesday, December 03, 2008

Rogue Waves

Imagine you're out at sea in a super tanker or stout cruise ship in heavy seas. Thirty foot swells come and go and other than praying to the porcelain idol from time to time you and your ship are no worse for wear. Then, ahead of you the sea rears up in a massive wall of water over a hundred and twenty feet tall - a rogue wave. What's worse, the trough before the wave accelerates your craft into it and lowers your bow so that all 120 feet of wave - creating over 100 tons of pressure per square meter, come crushing down on you like a fat man's sweet tooth on a crispy creme donut.
For years mariners have told of such waves- the ones lucky enough to survive them. In the past several years there have been a handful high profile losses to such waves which has piqued the curiosity of the scientific community.
The North Sea, off the coast of Norway, was angry that day, my friends. Hurricane-strong winds were blowing and twelve meter waves crashed on the Draupner oil rig. The rig’s workers were not worried, because the rig was designed to withstand hurricanes. At roughly 3 p.m. that afternoon, the order was given that all personnel must enter the rig’s structure- no one volunteered to stay outside and watch the ocean.
For this reason, no one saw the monstrous wave that hit the Draupner oil rig at 3:20 pm. The wave did not harm the rig itself (the platform was high above the water), but was recorded by a special laser-based wave-height detector. The rig’s engineers were shocked when they went over the detector's logs. The wave was almost 20 meters high. It was practically impossible- this kind of wave should only occur once every ten thousand years. Yet the laser detector was accurate to within an inch and worked
flawlessly. The wave’s existence was undeniable.
In 1899, a new lighthouse was built on a remote group of islands off the coast of Scotland, some 20 miles from the mainland. Three light house keepers were stationed at the lighthouse, and cared for the structure.
A year after the light house was erected, a supply ship came to the islands- as it did every week- to replenish the keepers' food supply. The ship's crew found the light house was empty. Its three keepers had vanished almost without a trace. Upon examining the scene, the ship's crew found that coats had been left behind, and a chair had fallen in the kitchen. These were considered as clues that hinted to a sudden catastrophe.
An examination of the lighthouse itself revealed damage to a metal box some thirty meters above the water's surface, a railing that was bent beyond repair, and a huge rock that was somehow moved from its place.
The official examiner speculated that a giant wave had hit the lighthouse- but since it was considered impossible that a wave this size might exist, alternative theories were invented to explain the men's sudden disappearance. Some speculated a fight had broken out between the keepers, others suggested murder, suicide, abduction by foreign agents, and even abduction by aliens- everything was possible.
Satellites using radar have spotted these gigantic rogue waves which occur much more frequently then anyone had imagined. The question remains what causes them?
Some distinct local weather patterns can cause inordinate swells along the coast of South Africa and in the deep water off of Norway, but what causes these waves in the open oceans? No one really knows for certain, but it appears that the monster waves siphon energy off the waves immediately adjacent to them, again why one wave does it and another does not is unclear.

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