| Autor: |
Stanton, T. K., Jezek, K. C., Gow, A. J. |
| Zdroj: |
Journal of the Acoustical Society of America; 1986, Vol. 80 Issue 5, p1486-1494, 9p |
| Abstrakt: |
Acoustical reflection and scattering properties of the underside of undeformed sea ice which was grown in an outdoor pond were studied. Echo amplitude fluctuations of normal incidence sonar pings (100-800 kHz) were measured as the sonars moved horizontally under the ice and accumulated into echo amplitude histograms. The Rice probability density function (PDF) was fit to the data and the resultant statistical parameter was combined with the Eckart acoustical scattering theory to estimate an rms roughness of the water/ice interface to be 0.3 mm. Because the ice thin sections showed the ice to be porous and permeable at the interface with dendrites 0.5 mm thick, it appeared that the dendrites controlled the scattering. The average reflection coefficient was of the order 0.05. The low reflection coefficient (low compared to the 0.35 value which is predicted from the bulk properties of sea ice) was attributed to the dendritic structure which was porous and permeable at the water/ice interface. From the data and modeling done, scattering, and, hence, echo fluctuations, for normal incidence sonars of various frequencies and beamwidths were also predicted. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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