A Radar Profile of a Multi-year Pressure Ridge Fragment
Keywords: Pressure ridges, Ice islands, Sea ice, Radar, Thickness, Measurement, Narwhal Island waters, Alaska
Abstract... In May 1977, impulse radar was used to profile the thickness of an ice island and the first-year sea-ice near our camp site on Narwhal Island, Alaska. At this location, a small fragment of a multi-year pressure ridge was found with good access to the ridge crest. The impulse radar system was taken to the ridge so that it could be used to ascertain if thick multi-year ice could be measured and if the thickness of the ridge along the crest could be profiled. A cross-sectional profile of the ridge was not attempted, because the ice surface was buried under a thick layer of drift snow. The impulse radar profiling system consisted of an electronics console, a graphic recorder and an antenna. The system and its operational characteristics have been described in several publications. The radar antenna was pulled for a distance of 21 metres along the top of the ridge. ... The signal information shown is the travel time of the radar impulse signal to and from the various reflecting surfaces. These include the surface of the ridge, internal block structure, and the irregular surface of the keel. ... This report demonstrates the potential usefulness of impulse radar for determining the thickness of multi-year pressure ridges. ...