The Wave That Changed ScienceMonday, March 03, 2008 - Ran Levi
Over the centuries many sailors described seeing huge ocean waves, monsters of the seas that towered to heights of 30 meters and more. Those Rogue Waves, as they were called, appeared suddenly and rammed into the unfortunate vessel. Scientists tended to ignore these stories. They considered them to be legends, fairy tales that sailors tell each other to pass the time on long journeys. They had good reason to doubt these stories: contemporary mathematical models predicted that the biggest possible ocean storm wave could be twelve to fifteen meters high.
But those tales, passed from one sailor to another in pubs or late at night on the ship's bridge, told also of a massive ‘hole’ in the water, tens of meters deep. This hole was followed by a nearly-vertical wall of water - a wave so steep no ship could 'climb' it. According to the stories, when a ship was hit by such a wave it usually drowned within seconds.
For a long time, scientists thought their understanding of ocean waves was reasonably good. The way they saw it, the mathematical models that were developed for other kinds of waves, like sound waves and electromagnetic waves, could be applied to waves in the ocean. And why should these models not be appropriate? A wave is just a wave, after all - an interference making its way from point A to point B, energy being transported from one place to another. Based on these mathematical models, scientists believed a thirty meter may exist, but is likely to occur only once every thirty-thousand years. Thus, Rogue Waves reports were placed in the same category sea-dragon stories, Bermuda Triangle oddities, and mermaid tales.
A single wave that crashed on a tall oil-rig in the northern Atlantic Ocean shocked the foundations of these scientific models.
In 1978, the merchant ship ‘Munich’ set sail on a regular voyage across the Atlantic Ocean, transporting goods from Germany to the United States. The Munich was the jewel in the German merchant fleet's crown; it was over two hundred meters long and equipped with the best technology money could buy. No storm or hurricane could possibly harm the Munich.
At 3 A.M, on December 12th, 1978, a Greek ship received an S.O.S message from the Munich. An emergency task force of almost a hundred ships and planes combed the Atlantic, but no trace of the Munich was ever found.
The Munich’s disappearance was a great mystery. The weather had been rough, but should not have posed any serious danger to the large vessel. The matter became even more mysterious when the search party located an empty life boat that had belonged to the Munich, floating in the water. Bent and broken pins on the life boat’s side indicated that the boat was not purposefully lowered to from the ship by the Munich’s crew, but was thrown over-board as a result of a massive impact. However, the Munich’s life boats usually hanged twenty meters above the water's surface! What tremendous force could have reached that height, knocking the raft out of place and possibly sinking the entire ship?
The formal investigation team concluded that the Munich drowned as a result of an unknown weather-related event, but many suspected that a Rogue Wave was the real culprit. Since no proof was available, this view was never adopted by the authorities.
This all changed on New Year’s Eve, 1995.
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.
Where then did the Draupner Wave, as it came to be known, come from?
It could not have been a Tsunami wave, since Tsunami waves grow large only when approaching land. It could not have been a Tidal Bore, a wave caused by tidal forces, since these only occur near the shore and are a much more localized phenomena.
It became obvious that a new theory must be developed to explain Rogue Waves. The first stage of every theory development is searching for facts. When the researchers looked back at all the data collected from sea buoys and ocean-waves radars, they were amazed at what they found. Instead of one report of a giant wave every thirty thousand years, Rogue Waves seemed to occur very often. Why, then, did ships encounter them only rarely? The answer was obvious- Rogue Waves exist for several minutes only, and disappear almost as soon as they are formed.
It was now also possible to open the history books and re-examine past mysteries in the light of the new knowledge. One such historical enigma is the ‘Flannen Island Mystery;’
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.
It is now believed that two of the keepers were working near the water, when the third spotted a Rogue Wave approaching the island. He ran outside to warn the others, not stopping to pick up the fallen chair or take his coat with him, but the monstrous wave washed all three.
A different, even more famous case involved the ‘Queen Mary’, a giant passenger ship. During the second world-war it was used to transport troops from the U.S. to Europe. In December 1942, with sixteen-thousand soldiers on board, it was hit by a huge wave. This monster wave, almost thirty meters high, crashed into the ship’ side and caused it to reach a 52 degrees tilt.
The ship slowly straightened, and barely managed to sail back to harbor. The engineers who examined the damage remarked that had the ship tilted by just three more degrees it would have capsized, killing everyone on board. This incident had the potential to end so tragically that it would have made the Titanic disaster seem negligible.
Using satellite imagery, it became obvious the there are certain areas around the globe that are more prone to Rogue Wave activity. Places where ocean currents meet waves that travel at opposite directions are especially dangerous. Those areas were quickly removed from shipping lanes listings.
But Rogue Waves occur in other places as well, places that have no strong currents or high waves. Today, the scientists' opinions remain divided as to the source of these waves. Generally speaking, two kinds of theories are competing for supremacy: linear theories versus non-linear theories.
Linear theories explain Rogue Waves as the additive sum of two smaller waves: that is, when a ten meters high wave ‘climbs’ upon another ten meter high wave, we get a single monster wave that reaches a height of twenty meters. For example, it is well know that high frequency waves travel slower over the ocean than low frequency waves. It is possible for a slow frequency series of waves to ‘chase’ and overtake a higher frequency group of waves, and 'climb' over them.
Critics of the linear theories say that these theories can only explain how under a very specific set of circumstances a Rogue Wave is produced. These are circumstances that occur very rarely, and can not account for the high number of Rogue Waves that have been reported over the years.
Non-linear theories take a very different approach. They try to explain Rogue Waves using equations and ideas taken from quantum mechanics. Schrodinger’s Equation, for example, is a famous equation used to explain and predict the behavior of electrons in orbit around the atom’s nucleus. It does so by treating the electrons as waves traveling around the atom. A version of this equation, known as the Non-Linear Schrodinger Equation, is highly effective when used in optics, and - as it turns out- in explaining Rogue Waves. According to this equation, an ocean wave might start to ‘suck’ energy from nearby waves, gaining height at the expense of the surrounding waves. This could account for the ‘hole in the water’ phenomenon reported by sailors who survived encounters with Rogue Waves.
As mentioned above, all Rogue Wave theories are still very much a work in progress. Technological advances might have given us the impression that we have managed to ‘tame’ the sea, that our huge ships and sophisticated radars have made the voyage over the ocean safe, almost boring.
However, nature proves time and again that we are neither as smart nor strong as we like to think we are. At least for the near future, sailors still need to keep their binoculars close at hand, and should keep scanning the horizon for Rogue Waves, and maybe for other sea monsters science has yet to recognize.
WEATHER NOTES
Whirlwind Strikes West Java, destroys 294 houses
Filed under: Storm
Whirlwind devastated at least 294 houses, school and local hospital buildings at Sukabumi district, West Java province, on Friday at 16:15 pm local time, leaving no victims.
The afternoon whirlwind which damaged three villages at Parung Kuda sub district had cost the local population material loss amounting to Rp 369 million, said the sub district officer Tendy Hendrayana.
Hendrayana reported that the whirlwind which struck Bojongkokosan, Langensari as well as Kompa villages, had left hundreds of buildings without electricity for hours.
The local government officers accompanied with villagers had been repairing the devastated buildings, he said.
To date, Sukabumi government and Indonesian Red Crescent Institute (BSMI) had been contributing 600 kg of rice as well as medicines and instant noodles to the villagers.
We urged the government to distribute the assistances to correct the situation, Hendrayana saidMethod To Estimate Sea Ice Thickness
ScienceDaily (Mar. 7, 2008) — Scientists recently developed a new modeling approach to estimate sea ice thickness. This is the only model based entirely on historical observations.
The model was developed by scientists with the U.S. Geological Survey and the Russian Academy of Sciences, Moscow.
Using this new technique, the thickness of Arctic sea ice was estimated from 1982 to 2003. Results showed that average ice thickness and total ice volume fluctuated together during the early study period, peaking in the late 1980s and then declining until the mid-1990s. Thereafter, ice thickness slightly increased but the total volume of sea ice did not increase.
Scientists propose that the volume stayed constant during the study's latter years because while the ice was thickening in the high latitudes of the Arctic, the surrounding sea ice was melting. Sea ice, however, can only become so thick, and if Arctic sea ice continues to melt, the total volume of sea ice in the Arctic will decrease.
The most dramatic losses in sea ice cover have occurred since 2003, and as scientists acquire newer data, they will apply the new model to study recent years of ice thickness and volume change.
This modeling approach uses sea ice motion data to follow parcels of ice backward in time at monthly intervals for up to 3 years while accumulating a history of the solar radiation and air temperature to which the ice was exposed. The model was constructed by fitting these data with an ice parcel's known thickness to determine how the thickness of sea ice changes in response to different environmental conditions. Data on the known thickness are obtained from measurements by submarine cruises and surface coring missions.
"Sea ice is affected by the accumulation of environmental factors to which it has been exposed," said USGS Director Mark Myers. "Understanding the natural variability of sea ice thickness is critical for improving global climate models. Sea ice regulates energy exchange and plays an important role in the Earth's climate system."
This model, built on historical observations, complements thermodynamic models that simulate ice thickness. Science benefits from having different models. Comparing different model outputs can help improve predictive capabilities. Many scientists worldwide are using satellite and ground observations of the Arctic's atmosphere, ice and ocean to gain a better understanding of how changes at the top of the world affect ecosystems both locally and globally.
The report "Fluctuating Arctic sea ice thickness changes estimated by an in-situ learned and empirically forced neural network model" was recently published in the Journal of Climate and can be found at the American Meteorological Society's journal site.
Adapted from materials provided by United States Geological Survey.
MARITIME NOTES
Then and Now: Under the Riverdance ferry
THOUSANDS of visitors - and locals - are still flocking to the seafront to view the stranded ferry Riverdance. But when they walk along Princess Way how many know what lies beneath their feet?
The answer is the former Little Bispham underground car, with spaces for 90 cars, which opened in 1935.
Passers-by might see metal doors at the bottom of a slope but will have no idea how big the subterranean space is.
Memory Lane reader John Knowles, now 77, recalls that before the Second World War his family had a box type Austin and they went down to the beach for a walk and a picnic with sandwiches and, his favourite, a bottle of Tizer. It was quite exciting, he says, as a young boy, to be driven into an underground car park.
Edmund Wynne, former "father" of Blackpool Council, and real-life dad of current Mayor Robert Wynne, actually ran the underground car park, as well as the West Street multi-storey, when he took over the lease of several council car parks in the early 1960s.
He paid the council an annual rent of £10,000, immediately cut the charges to motorists and managed to turn a £15,000 loss into a profit, giving his staff, mainly ex-servicemen, a regular bonus.
Edmund says some councillors thought he was out of his mind but he knew he could do it.
The council eventually voted to take the lease back and, as he says, car park prices rocketed.
These days the huge vault is leased to Fylde Boat Angling Club to store boats, tractors and other equipment.
And if motorists were down there, not only would they get a ticket from a warden for overstaying their time, but there would also be a free car wash as the high tide floods up through the drains twice a day!
RS
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