Detection and Mapping of Oil Spills under Sea Ice

FY 2011 | 3 – Inform | 11/10/09

Detection and Mapping of Oil Spills under Sea Ice

Jeremy Wilkinson
Scottish Association of Marine Science

Hanumant Singh
Woods Hole Oceanographic Institute

Contract Term: 7/1/11-6/30/12
Award: $70,307

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. To date, no surface-based technique has proven reliable for the detection of oil from above. Such methods are slow, labor-intensive, and most importantly, impractical to impossible in the dynamic, marginal ice conditions that will often be found in areas where oil exploration and ship traffic is most likely to occur. Airborne systems suffer from the need to effectively see through ice and snow cover for continuous ice. The only feasible means for detection and accurate mapping of oil distribution under sea ice over large areas and all ice conditions is from below. DAMOS will develop and test a suite of sensors for mounting on an autonomous underwater vehicle (AUV) for detection and mapping of oil under the full range of ice conditions and oil conditions expected to occur. This approach has the advantage of being independent of ice conditions and allows direct measurement of the oil (both under the ice and in the water column), unlike surface-based methods. The objectives of DAMOS are:
  1. Desk study: Theoretically examine and understand the benefits and limitations of sensors capable of detection and mapping of oil under the ice for the full range of conditions. This includes hydrocarbons under thin or thick ice with a snow cover, continuous or broken scattered floes, and under calm or highly dynamic conditions.
  2. Tank experiments: Perform realistic experiments with this sensor suite in an ice tank under a variety of hydrocarbons and sea ice (with snow) conditions
  3. Analysis: Determine the efficacy and accuracy of each sensor, including possible sensor combinations, for mapping hydrocarbons in varying conditions, and identify the most promising strategies for future development of an expert system that can interpret sensor data in near-real-time and the deployment of an AUV system dedicated to hydrocarbon detection.

The sensor suite will include three existing sensors: 1) a low-light and active camera system for positive visual detection of hydrocarbons under ice, 2) a multibeam sonar for detection and quantification of slick and pooling thickness, and 3) an optical system for detection of fluorescence from oil in and under sea ice. The anticipated final suite on an AUV platform will include an already proven mass spectrometer for the detection of hydrocarbons dispersed in the water column. First, a comprehensive theoretical desk study will evaluate each sensor so that the requirements for each can be refined prior to testing. To evaluate the success and limitations of each sensor, or combination of sensors, realistic and repeatable in situ testing will be conducted in an ice tank facility at the US Army Cold Regions Research and Engineering Laboratory. Through tests using varying ice and oil properties, the feasibility and accuracy of the system to detect hydrocarbons located under, or encapsulated within, sea ice will be quantified. A primary focus will be not just on the detection of hydrocarbons, but also a quantitative mapping of their distribution. This analysis will point the way for the future development of an expert, a multi-sensor system for near-real-time detection of both the extent and volume of hydrocarbons and for future AUV deployment strategies. Based on these results, the DAMOS group will pursue further funding for the development and testing of a complete AUV system. This approach will not only lead to an effective system for oil spill response, but an instrumented AUV will also characterize the three-dimensional environment of the hydrocarbon distribution under the ice with the potential to greatly advance our understanding of the behavior of oil dispersal in the sea ice environment.