An Experimental Investigation of an Acoustic Technique to Determine Shallow Water Bottom Boundary Impedance
1992
Maiocco-Dillman, Lynne M.
Acoustic propagation is highly dependent on bottom properties, particularly in shallow water. In the past, bottom properties have been determined directly (e.g., using core samples). An alternate method of determining bottom properties uses inverse techniques, obtaining geophysical parameters by means of acoustic data. Calibrated acoustic measurements were made on the New Jersey continental shelf in an area with known geophysical properties. The experiment was conducted under known oceanographic conditions that were shown by measurements-of temperature, salinity, and sound speed versus depth. The acoustic measurements were performed with a vertical array of 24 equally spaced hydrophones, one of which was positioned on the bottom. A calibrated source transmitted discrete frequencies between 10 and 600 Hz for the collection of data. Low frequencies between 10 and 50 Hz were transmitted at discrete locations close to the measurement array. The water/sediment boundary impedance was calculated from the ratio of velocity to pressure.
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