Sonar Detection of Oil in and under Ice

Scope of Work:

A practical system for oil spill response in the sea ice environment must be capable of rapidly mapping the extent and quantity of oil over large areas and under a range of ice and weather conditions. This project will test and validate the detection of oil under ice using a single beam sonar and underwater cameras that can be readily mounted on an unmanned underwater vehicle (UUV). The aim is to develop a system for direct detection and quantification of oil from below so that oil spilled under broken or continuous sea ice can be detected, quantified, and its spill trajectory can be mapped. Such a system will have the advantages of being deployable in a range of ice conditions and capable of detecting and monitoring an oil spill in conditions that preclude traditional detection from above.

This project builds on previous successful tests performed by the present team and funded by OSRI. These tests carried out in the outdoor ice tank facility at the US Army Cold Region Research and Engineering Laboratory in Hanover, New Hampshire demonstrated that thin slicks of oil can be detected under ice using a combination sonar and camera system. This project will perform further tests using the combined sonar/camera system in controlled laboratory ice tank experiments to 1) Determine the acoustic signature of oil under sea ice, for both warm and cold oil, 2) Determine the evolution of the acoustic signature over time as the oil percolates into the porous structure and/or melts the ice underside, thus determining the coevolution of acoustic signature and oil/ice structure, 3) Determine the ability of sonar to detect oil as it becomes encapsulated in the ice, 4) Determine whether a camera system can reliably detect encapsulated ice (alone, or in conjunction with sonar), and 5) Provide recommendations for an optimized sensor system for deployment on a UUV. Results of this study will allow us to construct quantitative models of the sensor response to oil under, or encapsulated within, ice and provide an empirical basis for interpretation of under-ice measurements. These experiments will allow us to develop a complete sensor system to be integrated into UUVs for under-ice operations at WHOI.