Wireless sensor networks work well in monitoring the oceans. The concept has been tested and found to be watertight.
Norwegian research- and industry groups achieved attention in 2007 when they claimed that wireless sensor networks could help with the lack of effective environmental monitoring in the Arctic.
The institutions said it would be smarter to use such networks to get trustworthy, fast information rather than further manual monitoring with costly research cruises.
Last winter a small group of scientists found themselves testing the technology on board a boat off Horten in the Oslo fjord. With them, they had five yellow metre-long plastic tubes packed with electronics and batteries. The cylinders were dropped into the sea at intervals of several hundred metres. This gave the scientists a network of sensor nodes capable of both sending and receiving information.
“The whole thing is rather like building a subsea GSM system,” explains SINTEF scientist Tor Arne Reitan. “For example, if one of the sensors registers a high concentration of a particular environmental pollutant, it could trigger the whole network to monitor for the same chemical. This would provide more rapid and reliable mapping of such occurrences than a single sensor that could only provide the same warning several weeks or months later.”
The tests showed that the network was capable of configuring itself, and that it automatically included new nodes as these were dropped into the sea.
Special events and regions
Although the network of sensors could mean a cheaper and more reliable way of acquiring marine data, a network of five or six sensors will not cover much of the Barents Sea or any other of the Arctic’s areas in need of oversight.
Hundreds or even thousands of units might be needed, and even then, that would still only cover a limited area. For this reason, the scientists believe that the best solution would be to monitor particularly important areas and events. The units would not need to be moored in fixed positions, but could be released wherever they are needed.
“If there was an oil-spill in the Lofoten area, for example, 10 or 20 nodes could be dropped into the sea in order to monitor where the oil is being driven and how it breaks down. If we wanted to measure the number of cod on their spawning migration to Lofoten, we could place a line of sensors across their migration route,” says Reitan.
The research is now being taken a step further via two EU projects in which Kongsberg Marine and SINTEF are participants. SINTEF has also launched a group project called Ocean Space Surveillance, in which data from subsea sensor networks are combined with sophisticated ocean models in order to improve the interpretation of the measurements.
This technology will be highly relevant as an element of BarentsWatch, the Norwegian government’s programme for an integrated monitoring system for the oceans of the Arctic region.