Listening to the waves

Oceans cover most of the earth’s surface with an average depth of more than two miles. Placing observatory equipment anywhere in the vast area is highly expensive.

Yet, oceans are as essential to humanity as the air we breathe. Understanding the same requires detailed observation. Wave glider is a sensor carrying vehicle that moves through the ocean propelled entirely by wave energy.

In the year 2005, two Silicon Valley engineers Joe Rizzi and Roger Hine began building a device that would allow them to listen to the calls of humpback whales off the coast of the big island of Hawaii.

Wave glider  helps scientists to understand climate change better and the military to monitor the high seas. According to Jim Bellingham at the Monterey Bay Aquarium Research Institute, this is a transformational development.

The engine of the glider is about five feet long and sits 22 feet below the surface, tethered to a floating instrument platform equipped with sensors and the command centre.

This glider can record wide-ranging, long-term oceanic and atmospheric observations.To record the sea surface and atmospheric conditions, scientists use various techniques. Over 80 per cent of the heat that enters the climate system goes into the ocean, according to Dean Roemmisch, a professor of oceanography. As he understands, measuring the ocean temperature is the best way to measure global warming.

How they work

These new wave gliders can be deployed from shore by two people and can be controlled via satellite through an Internet interface.

Solar panels on the surface float, power the glider’s command, control and sensor systems. Back up batteries can provide 10 days of back-up energy source.The designing of these gliders is very simple.

When the surface buoy rises with a swell, it pulls the glider upwards. When the buoy falls, so does the submerged glider. Water pushing on the glider’s wings allows it to move horizontally while it rises and falls and a tail rudder controls its direction.

Travelling in a shallow saw-tooth pattern, it can move into the wind and swell and reach speeds up to two knots.

A wave glider is a two-part vehicle. It consists of a floating platform and a submerged weighted glider joined by a cable. The solar panels on the float provide power for the instrument’s rudder and satellite commands.

The passing waves lift the float and pull the glider upward. As the glider rises, passing fins are pushed downward generating enough thrust to push the glider forward and no electrical energy is used.

As each wave passes, the float and the glider fall, causing the fins to rotate and produce more thrust waves several inches high and is sufficient to move the vehicle at top speed. Normally scientists use battery powered gliders to study the ocean but these devices are able to take measurements vertically through the water column to depths of thousands of feet while the green powered wave glider records surface condition also.

Other potential uses for the wave glider include mapping the sea floor, improving tsunami warning systems and patrolling marine reserves

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