Overlooked technology: Satellite photos used to detec oil seeps
Satellite photos used to detect oil seeps
US scientists said they have discovered they can use satellite images to detect oil seeping from oilfields beneath the seafloor of the Gulf of Mexico.
Chuanmin Hu, an optical oceanographer at the University of South Florida-St Petersburg, and colleagues from the National Oceanic and Atmospheric Administration and the University of Massachusetts-Dartmouth said they have found they can detect oil seeping naturally from the seafloor by examining satellite images of streaks amid "sun glint" -- the reflected sunlight on the ocean's surface.
The researchers said oil decreases the roughness of the ocean surface. Depending on the angles of the satellite camera and of the light reflection, oil creates contrasting swaths that can show up in the images as either lighter or darker than the surrounding waters, said a report by UPI.
Hu said the new technique can provide 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.
Using imagery from the Moderate Resolution Imaging Spectroradiometer (Modis) instruments on Nasa's Terra and Aqua satellites, Hu and colleagues assert, is far cheaper because the data is collected daily and provided freely by Nasa, without the need for special observation requests.
The description of the new technique was published in January in Geophysical Research Letters, said a Goddard Space Flight Center report.
"This capacity for detecting oil in the ocean has great potential, not just for oil seeps but for responding to oil spills," said Chris Reddy, a marine chemist at the Woods Hole Oceanographic Institution in Massachusetts
The technique could be useful for detecting and monitoring oil spills from ships and other platforms, though Hu emphasized that the spills must be large enough (at least hundreds of metres or feet) to be visible in the Modis imagery.
If there is suspicion of a large human-caused spill, for instance, researchers would be able to review ocean imagery to see if the slick was present before the alleged spill, indicating a natural seepage.
On the other hand, Modis satellite imagery collected on a regular basis could help coastal managers track and mitigate the effects of large accidental spills.
The new method is not perfect, as cloud cover or a lack of sun glint can limit its use.
Hu and colleagues suggest it may be best used as a complement to SAR, which penetrates cloud cover and can be tilted to get the necessary imaging angle.
"If you can get an image on a two- to three-day time frame and anywhere on the globe, that's pretty spectacular," said Reddy.