Seaglider Breaks Record Exploring Under the Ice in Arctic Waters
An autonomous, underwater vehicle monitors ocean conditions and water parameters in treacherous, ice filled arctic waters. The information it collects supports the understanding of ocean and related climate changes.
This photo shows the seaglider clearing its antennae from the water to send off data and receive mission instructions before plunging back into the arctic waters. The photo below shows the complete glider, which is about 3 metres (10 foot) long.
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The ocean currents, which are strongly dependent on density differences in water, have a major effect on sea temperatures around the world, which in turn effects the weather. One critical water flow is that from the Arctic through the Canadian Arctic Archipelago and Davis Strait into the Labrador Sea . With climate change and the melting of the ice cap an increase in water density can be expected in the Labrador sea, which could effect currents throughout the world.
Oceanologists and climatologists need to monitor this flow, 
but the normal technique of mooring instruments to the ocean bed is difficult because of the ice in the area. Propeller driven unmanned underwater vehicles also have difficulty in operating in this environment and need much closer maintenance and management. In particular they need to be recovered within hours of surfacing while the seaglider can wait for weeks for recovery.
The University of Washington’s Applied Physics Laborator has developed and optimised an under-ice seaglider which has just operated independently for a record six months, collecting and relaying a vast amount of information. The seaglider which can operate up to 1,000 metres (3,300 feet) below the surface has no propulsion but glides, by controlling its buoyancy and its attitude (angle compared to the horizontal). The buoyancy is adjusted by inflating or deflating an oil filled bladder, while the seaglider’s attitude is adjusted by moving the weighty battery pack backwards and forwards along a longitudinal shaft.
More interesting is the intelligence system that the glider uses to carry out its mission. It continually
- use specialised beacons when under the ice and GPS to determine its position
- considers how long it has been under the ice
- decides how urgent it is to try reach an opening in the ice so that it can transmit its data
- uses an internal ice atlas to weigh the odds of having open water above
- checks as it rises to see if the water temperature indicates an opening overhead
- compares the chance of damage against the need to download data
- dives or surfaces depending on this calculation
- monitors the status of mechanical, electrical and communications systems
- tries to get out from under the ice if it expects a system failure
- signals when it on the surface and can be picked up
When seagliders are on the ocean surface they can be commanded remotely from nearly anywhere in the world via the Internet and they transmit their data via satellite telephone.
Photo Credits:
Matthew Grund on Wikimedia Commons under a Creative Commons license.
University of Washington Press Release
This is really fascinating! I have watched programs about the challenges of research in frigid ocean waters. I had not seen this one as yet. Thank you.