are getting bigger

Bridie Smith

March 25, 2011 – 10:56AM

A surfer rides a large wave at Tamarama. Photo: Jon Reid

Ocean wind speeds and wave heights around the world have increased significantly over the past quarter of a century, according to Australian research that has given scientists their first global glimpse of the world’s rising winds and waves.

Published in the journal Science today, the research – the most comprehensive of its kind ever undertaken – used satellite data collected from 1985 to 2008.

It shows the extreme wave height off the coast of south-west Australia today is six metres on average, more than a metre higher than in 1985.

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“That has all sorts of implications for coastal engineering, navigation and erosion processes,” said Alex Babanin, an oceanographer at Swinburne University of Technology, Melbourne, and co-author of the paper.

However, there are greater uses for the data compiled by Professor Babanin, his Swinburne colleague Stefan Zieger and the Australian National University vice-chancellor, Ian Young.

To date scientists have largely focused on temperature as an indicator of climate change. But climate is about much more than temperature, as winds and waves control the flux of energy from the atmosphere to the ocean.

“Scientifically, this is another set of environmental properties which can be used as indicators of what is happening to the climate,” Professor Babanin said. “Temperature changes the global patterns of the pressure, pressure defines the winds, winds define the waves. It’s all connected.”

The trio established that between 1985 and 2008, global increases in wave height were most significant for extreme waves – large spontaneous waves. They increased in height by an average of 7 per cent in the past 20 years. In equatorial regions the rise was 0.25 per cent a year, while in higher latitudes the rise was up to 1 per cent a year. The mean wave height also increased, but to a lesser degree.

When analysing extreme wind speed data over the world’s oceans, the researchers found they increased by 10 per cent in the past two decades, or by 0.5 per cent a year.

Professor Babanin said waves were generated by wind. However, the data show the lift in wind speed was greater than wave height increase.

He said he doubted the 23 years of data could be immediately used to forecast future wind and wave conditions.

“These are the environmental properties which can be used as indicators for the climate behaviour along with the other properties, such as temperature and precipitation, and extrapolations have to be made with caution,” he said.

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Pathfinder subs would crawl

along the ocean floor

Philip Pauley’s proposed Pathfinder submarines would be able to crawl along the sea floor, or move through the water when necessary

The Transatlantic Seafloor Research Challenge is not a real competition, but that hasn’t stopped British designer Philip Pauley from envisioning it, and the watercraft that would take part in it. If it were to exist, the challenge would require underwater vehicles to cross from the UK to the US using whatever route their team members thought was the quickest, but they would have to stay in physical contact with the sea floor for as much of the distance as possible. Pauley’s Pathfinder submarines would be equipped with wheels or tracks for trundling along the bottom on most of the crossing, but would also theoretically be able to propel themselves up through the water when necessary.

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The designer estimates the trip taking between two and four weeks, during which time the submarines would maintain an average depth of at least 4,000 meters (2.5 miles). They would not be allowed to surface, but would instead be followed by topside support vessels that monitored their activities, and supplied life support and battery recharging power via umbilical cables. The support vessels would also be equipped with ROVs (underwater remote-operated vehicles), to assist the submarine crews in emergencies.

The Pathfinders themselves would be 10 to 15 meters (33 to 49 feet) in length, and would support a three-person crew. A lithium battery system would provide power for the wheels/tracks, and for the two-to-four side thrusters and rear propeller. All waste generated by the crew would have to be contained within the vehicle.

While the Transatlantic Challenge will presumably never happen, Pauley told us that he invented it as “a narrative to try to drive interest into the concept and engage investors.” Instead of winning races, he sees the subs being used more for scientific research and exploration.

When we asked about possible positive buoyancy issues with all those big fat tires, he replied that his hope is that they would be semi-solid. He admitted, however, that the optional heavy tracks could pose a negative buoyancy problem, and were pictured mostly to grab the attention of potential military customers. The windows, he added, were just included for wider audience appeal, and would not be part of an actual Pathfinder.

Given how such large windows would likely stand up to the pressure two and a half miles under the sea, that’s probably for the best

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Eyes, ears and brains being developed for underwater robots

Engineers from Germany’s Fraunhofer Institute for Optronics are working on an autonomous underwater vehicle (AUV) that would be inexpensive enough to use for industrial applications such as hull and dam inspection, yet independent enough that it wouldn’t require any kind of human control. Typically, more cumbersome but less costly remote operated vehicles (ROVs) are used for grunt work – they are connected to a ship on the surface by a tether, where a human operator controls them. The more technologically-advanced AUVs tend to be used more for well-funded research, but according to the engineers, one of the keys to creating “blue collar” AUVs is to overhaul the ways that they see, hear and think. Read More

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A NEW MEANING FOR ‘GOLD’ FISH
The Aquavista Dinosaur Gold Edition Aquarium – with Mammoth tusk and T-Rex bone inlays

Fancy an aquascaping and aquarium showcase in your lounge-room but don’t want the hassles of cleaning and feeding? No problems! Aquavista is pushing the envelope of automating all those tasks and its range-topping Panoramic model can be fitted with a Carbon Dioxide Generator that allows plants to photosynthesize and flourish, vastly simplifying the task of creating a ripsnorter underwater garden feature. Want to make sure you won’t be trumped by the Jones? No problems! Renowned bespoke luxury goods remanufacturer Stuart Hughes has just the ticket. Stuart’s latest creation starts with the Aquavista Panoramic, incorporates no less than 68kg of pure 24ct gold, has side veneers made from the tusk of a 14 ft Mammoth, inlaid with bone from a 17 ft T-Rex. If that doesn’t impress the visitors, mention the price-tag – GBP 3 million – around USD$4.8 million. Read More

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The Scenario: A man decided to have a quick cup of coffee. He places a cup of water in a microwave oven to heat it up (something he has done numerous times before). When the timer shut the oven off, he removed the cup from the oven. As he was about to add the coffee granules to the hot water, he noticed the water did not appear to
be boiling, but suddenly the water “blew up” into his face scalding him.
Why did this happen?

The water actually became “superheated.” Water boils at 100 degrees Celsius at normal atmospheric pressure but in a microwave oven it can be superheated without tell tale bubbles appearing. If a litre of water is superheated by only 1 degree, it is in an unstable state and can suddenly produce about 3 litres of steam while quickly returning to boiling point.
The following conditions promote this potentially dangerous event:- Using a container with a very smooth surface, such as an unscratched glass or glazed container; heating for too long; or quickly adding a substance such as coffee granules or even a spoon. Even a jarring action can cause it to “explode.”
How to avoid it:
• The best advice is not to heat water in a microwave oven. Use an electric jug or kettle or a saucepan on a stove.
• Before putting the water into the oven, insert a non-metal object with a surface that is not smooth. (e.g. a wooden stirrer).
• Use a container, the surface of which is at least a little scratched or not new.
• Do not heat for longer than the recommended time for the quantity of water used.
• Tap the outside of the container with a solid object while it is still in the microwave oven.
An explanation:

In a microwave oven, the water is usually hotter than the container, whereas parts of a kettle or saucepan are usually hotter than the water. Further, the surfaces of some containers used in microwave ovens may be very smooth, almost at a molecular scale, whereas this is not true for kettles or saucepans.
Microwave ovens heat the water directly: the microwaves pass through the container and the water, and the water itself absorbs energy from them. The container absorbs little energy directly. In a kettle or saucepan, the container itself (saucepan) or a heating element (some kettles) is hotter than the water. The hottest points cause a small amount of local superheating, boiling is initiated here, and this then stirs the water.

Received & published by Henry Sapiecha

Australia’s Moreton Bay

as Coral ‘Lifeboat’

Science (Aug. 13, 2010) — An international team of scientists has been exploring Moreton Bay, close to Brisbane, as a possible ‘lifeboat’ to save corals from the Great Barrier Reef at risk of extermination under climate change.

In a new research paper they say that corals have been able to survive and flourish in the Bay, which lies well to the south of the main GBR coral zones, during about half of the past 7000 years.

Corals only cover about 1 per cent of the Moreton Bay area currently, and have clearly been adversely affected by clearing of the surrounding catchments and human activities on land and sea, says lead author Matt Lybolt of the ARC Centre of Excellence for Coral Reef Studies and The University of Queensland.

“The demise of tropical coral reefs around the world is due mainly to overfishing, pollution and climate change. There is also plenty of historical evidence that coral reefs can move from one environment to another as the climate and other conditions change,” Matt explains.

“In view of this, various places — including Moreton Bay — are being investigated as possible refuges in which coral systems can be preserved should they begin to die out in their natural settings. Indeed, some people have even talked of relocating and re-seeding corals in other locations that better suit their climatic needs.”

The team’s study of Moreton Bay reveals that it is not exactly ideal coral habitat, being cold in winter, lacking sufficient direct sunlight, subject to turbid freshwater inflows and — more recently — to a range of human impacts.

“Even before European settlers came on the scene the Bay underwent phases in which corals grew prolifically — and phases in which they died away almost completely. We understand what causes corals to die back, but we are less clear about what causes them to recover,” Matt says.

“Broadly, the corals seemed to do well at times when the climate, sea levels and other factors were most benign and stable — and to decline when El Nino and other disturbances made themselves felt.”

The Moreton Bay corals have been in an expansionary phase during the last 400 years, initially dominated by the branching Acropora corals but, since the Bay’s catchment was cleared and settled, these have died back leaving mainly slow-growing types of coral.

“Under climate change we expect winters to be warmer and sea levels to rise — and both of these factors will tend to favour the expansion of corals in Moreton Bay,” Matt says.

“However this expansion of corals may not occur unless we make a major effort to improve water quality in the Bay, by not allowing effluent, polluted runoff or sediment to enter it, and also by regrowing mangrove forests and seagrass beds within the Bay. ”

The team concludes that Moreton Bay’s potential as a good ‘lifeboat’ for corals is limited by four major factors:

• It is highly sensitive to what the 2 million residents of its catchment do that affects it
• It presently has very few branching corals left
• The area on which corals can grow is limited, both naturally and by human activity
• Finally, the historical record suggests the Bay is only a good coral refuge about half of the time.

Matt says that there is nevertheless scope for changes in the management of the Bay and its surrounding catchments that can improve its suitability as a coral environment. “The reefs of today don’t look anything like they did in the past, so it’s really a question of ‘What sort of coral reef do you want?’,” he says.

However there needs to be a clearer scientific understanding of the drivers that have caused corals to boom and bust within the Bay over the past seven millennia before we can be sure it is worthwhile attempting to make Moreton Bay a ‘lifeboat’ for the GBR, he cautions.

Matt noted that there are very few suitable coral habitats south of the southern end of the GBR to which corals can migrate, should the northern parts of the reef become untenable for corals due to the impact of global warming.

Their paper “Instability in a marginal coral reef: the shift from natural variability to a human-dominated seascape” by Matt Lybolt, David Neil, Jian-xin Zhao, Yue-xing Feng, Ke-Fu Yu and John Pandolfi appears in the latest issue of the journal Frontiers in Ecology and Environment.

Sourced & published by Henry Sapiecha

Mimicking Insects to Avoid Sinking

Using Surface Tension

July 1, 2006 — A new robot made of ultralight carbon-fiber can stand or slowly walk on water. The principle it uses is borrowed from insects — surface tension tends to prevent the water’s surface from breaking, and the robot’s legs from sinking in.

PITTSBURGH — Nature inspires many things, from fashion to perfume to furniture. Now, technology gets a little inspiration.

After watching tiny bugs like these walk on water, Carnegie Mellon University mechanical engineer Metin Sitti wanted one of his own.

“We tried to make a robot to simulate the insect,” he tells DBIS. He tried and succeeded. This new tiny, lightweight, spindly legged creature is a robot that can propel itself across water in all directions. It can turn even sharp corners like the insect does, so it’s very agile.

The robot’s body is made of a super-light carbon fiber material. Its steel legs are coated with non-stick Teflon to repel water. A tiny battery gives it power.

“Right now we move by five centimeters per second, and the real insect can go up to one meter per second. So we are like around 20-times less speed,” Sitti says.

It might be slower, but just like insects, the robot doesn’t float. It stands on top of water thanks to the physics of surface tension. The surface is so strong that the robot’s feet only dent the water without breaking the surface while supporting the weight of the robot without sinking.

“When they put their legs on the surface of the water surface, they repel each other,” Sitti says. “And that repulsion can lift the body because it’s so light bodyweight.”

In the near future, Sitti says his creation could carry sensors to detect toxins in water supplies. “We can make many of them, like tens or hundreds of them, and cover a wide range and give you constant, continuous, water quality report,” he says.

Researchers have already received interest in the robot as an educational toy, to educate students and the public about water surface effects, and to provide entertainment.

LONDON (UPI) — A new ocean is being born in Africa that will eventually split the continent in two, British researchers say.

Scientists at Britain’s Royal Society say a 40-mile crack in the Earth opened in Ethiopia in 2005 and has been growing ever since, the BBC reported Friday.

The crack will eventually became the sea bed of a new ocean that will divide Africa in two, though the process will require about 10 million years, scientists say.

Used to understanding planetary changes on timescales involving millions of years, scientists say the crack in the remote Afar region of Ethiopia is dramatic in the speed at which it is growing.

The 40-mile crack opened to a width of 22 feet in just 10 days, they say.

Ultimately, they say, the horn of Africa will split from the continent, and the crack, in a region below sea level, will fill with salt water.

“It will pull apart, sink down deeper and deeper and eventually … parts of southern Ethiopia, Somalia will drift off, create a new island, and we’ll have a smaller Africa and a very big island that floats out into the Indian Ocean,” said Dr. James Hammond, a seismologist from the University of Bristol.

Copyright 2010 by United Press International

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New Study Helps Explain

Decompression Sickness

Science(June 28, 2010) — As you go about your day-to-day activities, tiny bubbles of nitrogen come and go inside your tissues. This is not a problem unless you happen to experience large changes in ambient pressure, such as those encountered by scuba divers and astronauts. During large, fast pressure drops, these bubbles can grow and lead to decompression sickness, popularly known as “the bends.”

A study in the Journal of Chemical Physics, which is published by the American Institute of Physics (AIP), may provide a physical basis for the existence of these bubbles, and could be useful in understanding decompression sickness.

A physiological model that accounts for these bubbles is needed both to protect against and to treat decompression sickness. There is a problem though. “These bubbles should not exist,” says author Saul Goldman of the University of Guelph in Ontario, Canada.

Because they are believed to be composed mostly of nitrogen, while the surrounding atmosphere consists of both nitrogen and oxygen, the pressure of the bubbles should be less than that of the surrounding atmosphere. But if this were so, they would collapse.

“We need to account for their apparent continuous existence in tissues in spite of this putative pressure imbalance,” says Goldman.

If, as is widely believed, decompression sickness is the result of the growth of pre-existing gas bubbles in tissues, those bubbles must be sufficiently stable to have non-negligible half-lives. The proposed explanation involves modeling body tissues as soft elastic materials that have some degree of rigidity. Previous models have focused on bubble formation in simple liquids, which differ from elastic materials in having no rigidity.

Using the soft-elastic tissue model, Goldman finds pockets of reduced pressure in which nitrogen bubbles can form and have enough stability to account for a continuous presence of tiny bubbles that can expand when the ambient pressure drops. Tribonucleation, the phenomenon of formation of new gas bubbles when submerged surfaces separate rapidly, provides the physical mechanism for formation of new gas bubbles in solution. The rapid separation of adhering surfaces results in momentary negative pressures at the plane of separation. Therefore, while these tiny bubbles in elastic media are metastable, and do not last indefinitely, they are replaced periodically. According to this picture, tribonucleation is the source, and finite half-lives the sink, for the continuous generation and loss small gas bubbles in tissues.

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WASHINGTON (UPI) — U.S. researchers say they’ve determined undersea forces produced by strong hurricanes are powerful enough to rupture underwater oil pipelines.

The scientists at the U.S. Naval Research Laboratory said the pipelines could crack or rupture unless they are buried or their supporting foundations are built to withstand hurricane-induced currents.

“Major oil leaks from damaged pipelines could have irreversible impacts on the ocean environment,” the researchers said, noting a hurricane’s winds can raise waves 66 feet or more above the ocean surface.

Based on unique measurements taken during a powerful hurricane, the researchers said their study is the first to show hurricanes propel underwater currents with enough force to dig up the seabed, potentially creating underwater mudslides and damaging pipes or other equipment resting on the bottom.

They said they’re not sure what strengths of forces underwater oil pipelines are built to withstand. However, “Hurricane stress is quite large, so the oil industry better pay attention,” said Hemantha Wijesekera, who led the study.

The findings are to appear in the June10 issue of the journal Geophysical Research Letters.

Sourced and published  by Henry Sapiecha