About half of the oil in the ocean bubbles up naturally from the seafloor, with Earth giving it up freely like it was of no value. Likewise, NASA satellites collect thousands of images and 1.5 terrabytes of data every year, but some of it gets passed over because no one thinks there is a use for it.
Scientists recently found black gold bubbling up from an otherwise undistinguished mass of ocean imagery. Chuanmin Hu, an optical oceanographer at the University of South Florida, St. Petersburg, and colleagues from the National Oceanic and Atmospheric Administration (NOAA) and the University of MassachusettsDartmouth (UMass), found that they could detect oil seeping naturally from the seafloor of the Gulf of Mexico by examining streaks amid the reflected sunlight on the ocean's surface.
Most researchers usually discard such "sun glint" data as if they were over-exposed photos from a camera. "Significant sun glint is sometimes thought of as trash, particularly when you are looking for biomass and chlorophyll," said Hu. "But in this case, we found treasure."
The new technique could provide a more timely and cost-effective means to survey the ocean for oil seeps, to monitor oil slicks, and to differentiate human-induced spills from seeps.
Oil decreases the roughness of the ocean surface. Depending on the angles of the camera and of the light reflection, oil creates contrasting swaths that can show up in airborne images as either lighter or darker than the surrounding waters.
The detection and monitoring of oil spills and seeps by satellite is not new. Visible, infrared, microwave, and radar sensors have all been used, with synthetic aperture radar (SAR) being the most popular and reliable method in recent years according to the study authors. SAR imagery can be very expensive, the authors note, and timely, repeat coverage is not always possible, particularly in tropical regions.
Using imagery from the Moderat
|Contact: Sarah DeWitt|
NASA/Goddard Space Flight Center