Author: James H. Getman
Publisher:
ISBN:
Category : Sea ice
Languages : en
Pages : 209
Book Description
An experimental apparatus for the measurement of the thickness of sea-ice by the use of a shear wave reflection technique was designed and constructed. The apparatus was tested extensively in the Arctic during the summer of 1972. A portion of the apparatus, the horizontal impact source, produced reliable and repeatable excitation of the ice. Unfortunately, the measurement of the thickness of sea ice by the use of a shear wave reflection technique was not as simple as was anticipated, primarily due to the difficulty of properly exciting the ice and to the mode conversion of the acoustic energy by external and internal features of the ice.
Development of a Sea-Ice Thickness Gage. An Attempt to Use Shear Waves
Author: James H. Getman
Publisher:
ISBN:
Category : Sea ice
Languages : en
Pages : 209
Book Description
An experimental apparatus for the measurement of the thickness of sea-ice by the use of a shear wave reflection technique was designed and constructed. The apparatus was tested extensively in the Arctic during the summer of 1972. A portion of the apparatus, the horizontal impact source, produced reliable and repeatable excitation of the ice. Unfortunately, the measurement of the thickness of sea ice by the use of a shear wave reflection technique was not as simple as was anticipated, primarily due to the difficulty of properly exciting the ice and to the mode conversion of the acoustic energy by external and internal features of the ice.
Publisher:
ISBN:
Category : Sea ice
Languages : en
Pages : 209
Book Description
An experimental apparatus for the measurement of the thickness of sea-ice by the use of a shear wave reflection technique was designed and constructed. The apparatus was tested extensively in the Arctic during the summer of 1972. A portion of the apparatus, the horizontal impact source, produced reliable and repeatable excitation of the ice. Unfortunately, the measurement of the thickness of sea ice by the use of a shear wave reflection technique was not as simple as was anticipated, primarily due to the difficulty of properly exciting the ice and to the mode conversion of the acoustic energy by external and internal features of the ice.
Selected Water Resources Abstracts
Sea Ice Thickness Measurements Using Shear Wave Reflections
Author: George P. Vance
Publisher:
ISBN:
Category : Sea ice
Languages : en
Pages : 160
Book Description
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).
Publisher:
ISBN:
Category : Sea ice
Languages : en
Pages : 160
Book Description
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).
Selected Water Resources Abstracts
Sea Ice Analysis and Forecasting
Author: Tom Carrieres
Publisher: Cambridge University Press
ISBN: 1108417426
Category : Science
Languages : en
Pages : 263
Book Description
A comprehensive overview of the science involved in automated prediction of sea ice, for sea ice analysts, researchers, and professionals.
Publisher: Cambridge University Press
ISBN: 1108417426
Category : Science
Languages : en
Pages : 263
Book Description
A comprehensive overview of the science involved in automated prediction of sea ice, for sea ice analysts, researchers, and professionals.
Physical Measurements of Sea Ice
Author: J. H. Brown
Publisher:
ISBN:
Category : Ice
Languages : en
Pages : 26
Book Description
During the Winter 1954 Bering Sea Expedition and the Winter 1955 Bering Sea Expedition, measurements were made of the longitudinal plate-wave velocity. In 1954, the location of the ice sheet in which measurements were made was 60 deg 20 min N, 168 deg 38 min W; and in 1955 the ice sheet, although variable in position during the several days measurements were being made, occupied the position 63 deg 05 min N, 166 deg 09 min W. In 1955, in addition to the measurement of the longitudinal plate-wave velocity, other physical properties of the ice which might be of scientific interest were measured. The investigation of other sea-ice parameters included: (1) sampling profiles of density, temperature, salinity, air bubble, and crystal grain; (2) measurement of the longitudinal wave velocity in ice rods; (3) measurement of the frequency of air-coupled flexural waves to determine ice thickness; and (4) resistivity measurements.
Publisher:
ISBN:
Category : Ice
Languages : en
Pages : 26
Book Description
During the Winter 1954 Bering Sea Expedition and the Winter 1955 Bering Sea Expedition, measurements were made of the longitudinal plate-wave velocity. In 1954, the location of the ice sheet in which measurements were made was 60 deg 20 min N, 168 deg 38 min W; and in 1955 the ice sheet, although variable in position during the several days measurements were being made, occupied the position 63 deg 05 min N, 166 deg 09 min W. In 1955, in addition to the measurement of the longitudinal plate-wave velocity, other physical properties of the ice which might be of scientific interest were measured. The investigation of other sea-ice parameters included: (1) sampling profiles of density, temperature, salinity, air bubble, and crystal grain; (2) measurement of the longitudinal wave velocity in ice rods; (3) measurement of the frequency of air-coupled flexural waves to determine ice thickness; and (4) resistivity measurements.
United States Coast Guard Technical Reports, 1945-1974
Author: United States. Coast Guard. Office of Research and Development
Publisher:
ISBN:
Category : Naval art and science
Languages : en
Pages : 174
Book Description
Publisher:
ISBN:
Category : Naval art and science
Languages : en
Pages : 174
Book Description
Government Reports Announcements
Surface Temperatures and Growth of Sea Ice
Author: Michael A. Bilello
Publisher:
ISBN:
Category : Atmospheric temperature
Languages : en
Pages : 20
Book Description
Sea-ice surface temperatures observed at Eureka, N.W.T., Canada, during 1949-50 and 1950-51 were used to compute the numerical value of the expression k/L rho, where k = thermal conductivity, L = latent heat of fusion and rho = density. The numerical value for these combined physical properties of sea ice was found to increase from approximately 0.000047 to 0.00007 during ice growth (between 6 November and 22 December) from 0.6 to 1 m thickness. During the increase from 1.1 to 1.3 m (between 20 January and 10 February) the value of k/L rho ranged from 0.00007 to 0.00008 and then decreased slightly during the rest of the growth period. These variations in the value of k/L rho throughout the winter season were considered as changes in the effective conductivity caused by physical changes and distribution of brine in the sea ice. Since no observations on sea-ice salinity were made at Eureka, it was not possible to investigate the effect of the physical properties separately. A study on the relation between sea-ice accretion and temperature gradient disclosed a correlation coefficient of r = 0.73. (Author).
Publisher:
ISBN:
Category : Atmospheric temperature
Languages : en
Pages : 20
Book Description
Sea-ice surface temperatures observed at Eureka, N.W.T., Canada, during 1949-50 and 1950-51 were used to compute the numerical value of the expression k/L rho, where k = thermal conductivity, L = latent heat of fusion and rho = density. The numerical value for these combined physical properties of sea ice was found to increase from approximately 0.000047 to 0.00007 during ice growth (between 6 November and 22 December) from 0.6 to 1 m thickness. During the increase from 1.1 to 1.3 m (between 20 January and 10 February) the value of k/L rho ranged from 0.00007 to 0.00008 and then decreased slightly during the rest of the growth period. These variations in the value of k/L rho throughout the winter season were considered as changes in the effective conductivity caused by physical changes and distribution of brine in the sea ice. Since no observations on sea-ice salinity were made at Eureka, it was not possible to investigate the effect of the physical properties separately. A study on the relation between sea-ice accretion and temperature gradient disclosed a correlation coefficient of r = 0.73. (Author).