Operational Techniques for Oil Detection on the Ocean's Surface with Satellite Imagery

The Satellite Analysis Branch (SAB) within the satellite line office (NESDIS) of the National Oceanic and Atmospheric Administration (NOAA) provides real-time satellite based analyses of tropical cyclones, volcanic ash, wildfires and smoke, manmade oil spills, marine debris, and heavy precipitation. SAB operates on a 24x7x365 basis. The Branch's primary mission is to employ satellite analysis techniques needed to support disaster mitigation and warning services for U.S Federal agencies and the international community. The newest and most rapidly developing effort in SAB is the Marine Pollution Satellite Program. Analysts manually examine moderate and high resolution optical and Synthetic Aperture Radar (SAR) imagery over US waters (and international waters, when requested) to meet the NOAA Emergency Response Division's (ERD) request for analysis support for oil spills. Other clients include the US Coast Guard, the Bureau of Ocean Energy Management (BOEM) and the Bureau of Safety and Environmental Enforcement (BSEE). Optical imagery from MODIS (NASA), Sentinel-2 (ESA) and Landsat (USGS), as well as SAR imagery from Sentinel-1A (ESA) and RADARSAT-2 (CSA) are routinely scanned for possible oil anomalies. The advantage of optical imagery is the ability to generate composites that help distinguish oil from vegetation and other false positives. Disadvantages include being limited to daylight hours and cloud free weather conditions. SAR imagery allows for the detection of oil overnight and through clouds. Disadvantages associated with SAR include difficulty in positively identifying the substance on the ocean surface. Once a possible oil anomaly is identified, a wide array of ancillary data is consulted to help confirm the presence of oil. The ability to differentiate oil thicknesses in multispectral imagery will soon be implemented into future analysis. Ground truth experiments in conjunction with BSEE are planned to take place in FY17 within a controlled tank and the open ocean in order to determine the minimum detectable threshold of oil thickness with varying satellite spatial resolutions. Once identified, the areas of thicker oil will help to direct oil spill responders to locations so they may concentrate recovery efforts.