File photo shows Norway’s Oil on Water exercise from 2010. Photo: NOFO
Scientists from NASA joined in on Norway’s annual oil spill cleanup exercise in the North Sea this year to test out some new oil detection equipment that could significantly help cleanup in the case of a major spill.
During the exercise held this month, NASA equipped one of its research aircraft with a specialized Uninhabited Aerial Vehicle Synthetic Aperture Radar, or UAVSAR, to monitor the release of oil into the sea, testing the radar’s ability to distinguish between more and less damaging types of oil slicks.
Norway’s Oil on Water exercise has been held annually since the 1980s and involves the controlled release of oil into the ocean, giving responders the chance to practice with existing cleanup techniques and equipment and a chance to test new technologies.
The potential for the UAVSAR’s to classify the oil in an oil slick was first observed during the 2010 BP Deepwater Horizon oil spill in the Gulf of Mexico. However, since officials only had only estimates of how much oil was being released, researchers could not fully check UAVSAR’s accuracy.
“Radar has long been thought to be useful only for telling where oil is present,” said Cathleen Jones, one of the three scientists from NASA’s Jet Propulsion Laboratory in Pasadena, California invited to attend the exercise. “That information is important, but it’s not all that’s needed to direct the response to an oil spill.”
Because the same accident can create both light sheens of oil a few hundredths of an inch thick and heavy, sticky emulsions of oil and seawater depending on factors such as the weather and length of time since the spill, it is important for responders to know what areas of a spill are of the highest priority.
“Thick emulsions hang around in the environment much longer than a sheen does,” Jones explained. “They’re more likely to make it to shore to contaminate coastal and tidal zones and to oil sea animals. If we can identify where that high-environmental-impact oil is, cleanup crews can get the most out of the time and people they have.”
NASA describes how the radar works:
Radars “see” an oil spill because of a characteristic that the Greek philosopher Aristotle first wrote about 2,500 years ago: pouring oil on water smooths the surface. To an observer, returning radar signals — called backscatter — from a smooth, oily sea surface look darker than backscatter from a normal sea surface with small, bumpy waves.
During their observations of the Gulf oil spill, the NASA scientists discovered that the extremely sensitive UAVSAR could also detect another characteristic of oil: compared with seawater, it is a very poor conductor of electricity. Radar waves are reflected well by materials with good electrical conductivity, such as seawater, and not so well by poor conductors like oil. For that reason, the strength of the backscatter from different parts of an oil slick is related to the thickness of the emulsion in each part.
In order to calibrate the UAVSAR data, the Norwegian exercise released emulsions of differing thicknesses so that the scientists could have a range of conditions to work off of. The experiment also tested the instrument’s ability to distinguish between petroleum and plant-based oil, found in algal blooms. “In the Baltic Sea you will see plenty of these, and they look like oil slicks from [radar on] a satellite,” commented Camilla Brekke, associate professor in the Department of Physics and Technology at the University of Tromsø, Norway.
NASA notes that Norway is one of a few nations worldwide that allows oil to be discharged at sea to test new cleanup technologies and procedures. This year, Oil on Water was held at the abandoned Frigg Oilfield, about 140 miles (230 kilometers) northwest of Stavanger, Norway.
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