Airborne radar tracks slicks via sea state analysis

Sources of oil pollution off the Norwegian coast stand less chance of escape thanks to the use of airborne radar by the Norwegian Pollution Control Authority - Statens Forurensningstillsyn (SFT). Light aircraft now maintain patrols over the Norwegian sector of the North Sea which they monitor with MSS 5000 SLAR (side looking airborne radar) systems supplied by the Swedish Space Corporation.

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Th Manfig2
An oil spill detected on a routine mission is immediately located on the digital map when the SLAR image is superimposed.
Click here to enlarge image

Sources of oil pollution off the Norwegian coast stand less chance of escape thanks to the use of airborne radar by the Norwegian Pollution Control Authority - Statens Forurensningstillsyn (SFT). Light aircraft now maintain patrols over the Norwegian sector of the North Sea which they monitor with MSS 5000 SLAR (side looking airborne radar) systems supplied by the Swedish Space Corporation. The entire Norwegian coastline is patrolled by aircraft every week while the country's oil fields are flown over daily.

The air crews have the job of spotting oil spills and identifying their source from the air. They are supported in this task by images supplied by satellites in polar orbits, the tracks of which regularly follow the Norwegian coast. The high altitude of the satellites and the resolution of the images they supply enable huge areas of the North Sea to be observed in a single pass. The satellite images are received in Tromso where they are studied for any indications of oil pollution. If anything is spotted by the trained observers an alert goes to the SFT which will then send an aircraft to take a closer look.

Oil pollution is not always easy to spot from the air but the SLAR overcomes any difficulties by looking not at the oil, but at the sea that surrounds it. From an altitude of just 2,500 ft, the radar carried by the small pollution control aircraft monitors a swath of sea extending to more than 40 nautical miles on either side. The predominant reflections received by the SLAR take the form of enhanced clutter generated by the irregular surface of the sea. The calming effect of oil on troubled sea water consequently betrays the existence of an oil slick as it reduces the amount of clutter from the affected area.

Because the aircraft is able to cover such a wide expanse of sea, polluting vessels or platforms may not be aware that they have been observed until the aircraft appears directly overhead. The advanced battery of conventional and infra-red cameras that form part of the MSS 5000 package carried by the aircraft is used to identify the offending installation and to provide the evidence needed for a successful conviction.

"Oil spills are being spotted all the time," said Olov Fäst, airborne systems manager for the Swedish Space Corporation. "The system is being used quietly every day so it is a healthy reminder to the offshore operators that they must keep to their agreements."

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The Swedish Space MS 5000 system has been designed to give an effective working environment onboard the aircraft (photo by Arne Nesheim).
Click here to enlarge image

The SLAR system was first used for pollution monitoring in the North Sea in the 1980s. It has been subjected to continual improvement since then and is now being delivered to the Greek and Polish maritime authorities in addition to the Swedish Coastguard which recently purchased an upgrade of its existing system. The most prestigious recent contract has come from the US Coast Guard which has been using the SLAR system for several years and has recently ordered an upgrade package of the monitoring equipment which it can also use for search and rescue operations around the North American coastline.

For further information contact Olov Fäst, Swedish Space Corporation. Tel +46 8 98 70 69, Fax +46 8 98 70 69, Email: olov.fast@ssc.se

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