Accession Number : AD0739743

Title :   Sea Ice Thickness Measurements Using Shear Wave Reflections,

Corporate Author : COAST GUARD ACADEMY NEW LONDON CONN

Personal Author(s) : Vance,George P. ; Benefield,Daniel D. ; Egan,Dennis M.

Report Date : DEC 1971

Pagination or Media Count : 160

Abstract : Because of the lack of success in measuring sea ice thickness with normal acoustic means, a method utilizing shear waves or 'S' waves was tried during the summer of 1971 off Point Barrow, Alaska. A 551A*Textronic oscilloscope and polaroid camera were used to record the signals received. Two Columbia High Capacity accelerometers were used for triggering the scope and obtaining the return signal. A three pound sledge-hammer impacting on a six inch diameter steel plate was used as the 'S' wave source. Results were obtained in ice thicknesses from 7.0 feet to 21.0 feet thick. An average 'S' wave speed in sea ice of 6.56 feet per millisec was used. In comparing the recorded signals with physically measured thicknesses, the average error was found to be 6.6%. (Author)

Descriptors :   (*SEA ICE, THICKNESS), (*ALASKA, SEA ICE), MEASUREMENT, SEISMIC WAVES, REFRACTION, ULTRASONIC RADIATION, ACCELEROMETERS, OSCILLOSCOPES

Subject Categories : Snow, Ice and Permafrost

Distribution Statement : APPROVED FOR PUBLIC RELEASE