Development of acoustic remote sensing techniques for sea ice, oil under sea ice, and oil encapsulated in sea ice

Recent decreases in sea ice cover have provided new opportunities for the shipping industry and stimulated further interest in hydrocarbon extraction in Arctic waters, thereby also increasing the risk of an oil spill in ice covered waters. To support oil spill response there is a need to develop practical remote sensing techniques to detect, quantify, and map oil that is under or encapsulated in sea ice. To address this need, a series of experiments were conducted at the Cold Regions Research and Environmental Laboratory (CRREL, Hannover, NH). During these experiments, different amounts of crude oil were injected underneath artificially grown sea ice of different thicknesses. The ice and oil were monitored by a suite of instruments located in the water column, including cameras, laser fluorometers, and multibeam, narrowband, and broadband acoustic backscattering systems. In addition, temperature and salinity profiles were conducted routinely, and ice cores were collected and imaged using a micro-CT scanner. Results from the broadband acoustic backscattering system are presented, and the relative merits of this approach for the remote detection and quantification of oil under and in sea ice are discussed. In addition, the utility of the acoustic systems for studies of ice physics are also discussed.