1 Detection and quantification of oil under sea ice: the view from below 1

Abstract 11 Traditional measures for detecting oil spills in the open-ocean are both difficult to 12 apply and less effective in ice-covered seas. In view of the increasing levels of 13 commercial activity in the Arctic, there is a growing gap between the potential need 14 to respond to an oil spill in Arctic ice-covered waters and the capability to do so. In 15 particular, there is no robust operational capability to remotely locate oil spilt under 16 or encapsulated within sea ice. To date, most research approaches the problem from 17 on or above the sea ice, and thus they suffer from the need to ‘see ’ through the ice 18 and overlying snow. Here we present results from a large-scale tank experiment 19 which demonstrate the detection of oil beneath sea ice, and the quantification of the 20 oil layer thickness is achievable through the combined use of an upward-looking 21 camera and sonar deployed in the water column below a covering of sea ice. This 22 approach using acoustic and visible measurements from below is simple and effective, 23 and potentially transformative with respect to the operational response to oil spills in 2