ANNUAL MEASUREMENT OF SEA-ICE THICKNESS USING AN UPWARD-LOOKING SONAR

THE difficulties in collecting reliable data in polar regions are nowhere more acute than in sampling sea-ice growth and thickness. Yet ice dynamics and the forms the ice takes are of great importance to operators in polar conditions. Offshore rigs, harbours and icebreaking ships, for example, depend on reliable estimates of the sizes, distributions and mechanical properties of pressure ridges and undeformed floes. Here I report measurements of sea-ice thickness in the Canadian Beaufort Sea, using a bottom-mounted upward-looking sonar device operated for 250 consecutive days. Although carried out over a decade ago, the project is, as yet, the only successful experiment of its kind. © 1990 Nature Publishing Group.