Oil Slick Characterization with UAVSAR

Although radar has long been used for mapping the spatial extent of oil slicks, its capability for characterizing oil, e.g., to discriminate thicker from thinner oil or mineral slicks from look-alikes, is far less well defined. In fact, the capability of SAR to quantify the oil-to-water ratio of emulsions within slicks on the open water was first demonstrated using UAVSAR data acquired over the 2010 Deepwater Horizon spill in the Gulf of Mexico [Minchew et al., 2012]. UAVSAR's capability was made possible by the airborne instrument's high signal-to-noise ratio, which enabled it to measure low backscatter signals from oil-smoothed water that are often near or below the noise floor of satellite SAR instruments. Since 2010, UAVSAR has been used to study oil slicks through experiments in Norway (2015) and the Gulf of Mexico. In November 2016, UAVSAR took part in a NOAA-led experiment to study remote sensing of oil slicks, which took place at the site of a persistent seep in the Gulf of Mexico. The goal was to use remote sensing to identify zones of thicker oil, which is the type of information that could direct emergency responders for more effective clean-up. The objectives of the experiment were to validate and compare different remote sensing methods' capabilities for measuring the thickness of oil within a slick on open water under environmental conditions typical of oil spills. In this presentation, we show the results from UAVSAR for determining oil thickness within a slick, and relate them to the standard method of oil slick classification, the Bonn Agreement oil appearance code used by trained observers in the field. This work was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under contracts with the California Dept. of Water Resources and with the National Aeronautics and Space Administration.