NASA Jet Propulsion Laboratory (JPL) researchers have developed a method of using a specialized 3-D imaging radar to "characterize" the oil in oil spills. This represents the first time it has been demonstrated that such a radar system can be used to distinguish thin films, such as oil sheen, from from thick oil emulsions.
The technique was developed in part in 2010, during the BP Deepwater Horizon oil spill. Researchers used the JPL-developed Uninhabited Aerial Vehicle Synthetic Aperature Radar (UAVSAR) to collect radar imagery (such as that seen above) over the main slick of the BP spill on three deployments between June 2010 and July 2012. A NASA C-20A piloted aircraft was used to transport the UAVSAR, which was mounted in a pod beneath the aircraft.
"Our research demonstrates the tremendous potential of UAVSAR to automate the classification of oil in a slick and mitigate the effects of future oil spill tragedies," said Cathleen Jones, a researcher at JPL. "Such information can help spill incidence response commanders direct cleanup operations, such as the mechanical recovery of oil, to the areas of thick oil that would have the most damaging environmental impacts."
Current oil classification techniques rely on visual surveys from experts. Remote sensing with UAVSAR can cover larger areas and is available at night or during poor weather conditions when visual surveys are not an option.
The UAVSAR categorizes an oil slick by detecting variations in the roughness of its surface and for a thick slick it measures the changes in electrical conductivity of its surface layer. NASA states that UAVSAR "sees" oil spills at sea as a radar-dark area against the rougher ocean surface because most of the radar energy hitting a smoother surface is deflected away from the radar antenna.
In June 2010, the UAVSAR collected data over an area of more than 46,330 square miles along the Gulf Coast. The data showed researchers that, at the time, much of the main oil slick from the BP spill was made up of thick emulsions of oil and seawater.
"We knew we were going to detect the extent of the spill," said Ben Holt, another researcher at JPL. "But we had this great new instrument, so we wanted to see how it would work in this extreme situation, and it turned out to be really unique and valuable, beyond all previous radar results for spills."
(Image courtesy NASA/JPL-Caltech)