Open-File Report 2010-1107
This report describes a method to create color-composite images indicative of thick oil:water emulsions on the surface of clear, deep ocean water by using normalized difference ratios derived from remotely sensed data collected by an imaging spectrometer. The spectral bands used in the normalized difference ratios are located in wavelength regions where the spectra of thick oil:water emulsions on the ocean’s surface have a distinct shape compared to clear water and clouds. In contrast to quantitative analyses, which require rigorous conversion to reflectance, the method described is easily computed and can be applied rapidly to radiance data or data that have been atmospherically corrected or ground-calibrated to reflectance. Examples are shown of the method applied to Airborne Visible/Infrared Imaging Spectrometer data collected May 17 and May 19, 2010, over the oil spill from the Deepwater Horizon offshore oil drilling platform in the Gulf of Mexico.
First posted July 21, 2010
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Kokaly, R.F., and others, 2010, A rapid method for creating qualitative images indicative of thick oil emulsion on the ocean’s surface from imaging spectrometer data: U.S. Geological Survey Open-File Report 2010–1107, 16 p.
Reflectance spectra of oil:water emulsions and normalized difference ratios
Color-composite images indicative of oil