Radar and Ice

Abstract

The need for investigations into the detection of ice by radar became apparent when merchant ships started reporting that ice formations were inconsistent radar targets, and that ships relying upon radar to navigate through ice areas could, in some circumstances, have their safety endangered.Certain investigations, notably those carried out by the U.S. Coast-guard Service and by the Swedish Defence Research Institute, resulted in the publication of a great deal of useful descriptive information but it was not accompanied by measurements of the actual echoing power of ice targets. With the object of carrying the matter further, a special enquiry was made during the 1950 and 1951 North Atlantic ice seasons, when a number of British ships plying North Atlantic routes completed questionnaires in which the sizes and shapes of ice formations were noted together with their radar detection ranges. This enquiry was instituted by the Operational Research Group in the Marine (Navigational Aids) Division of the British Ministry of Transport, which later analysed the data collected and issued a report. There were, however, certain limitations in this investigation. For example, the performance of the radars was not known, because of their inherent differences and the fact that none of the ships carried instruments, such as echo-boxes, for checking performance; further, propagation conditions at the time of making the observations were not established.