Measurements of Acoustic Backscatter of the Deep Sea Floor Using a Deeply Towed Vehicle.

摘要

In 1983 an area of Copper-Nickel rich manganese nodules at 14 deg 40 min N, 126 deg 25 min W (site 'E ) was intensively studied with the Deep-Tow of the Scripps Institution of Oceanography, and 16 box cores were collected. Deep-Tow studies of the Thirtymile-Bank off the California Coast and the deep sea at the foot of the Patton Escarpment followed. The nodule coverage at site 'E varies from 0% to 80%. The nodule sizes vary between 1 and 13 cm. The nodule size distributions are best modeled by a Gaussian distribution. The three main nodule axes are related to each other at 1:0.8:0.5. The average density of individual nodules is 2.0 + or - 0.04 g/cu cm and the volumes increase on the average with the 2.8 power of the third root of the product of the three radii. Changes of the thickness of the upper acoustic unit of the sediment column correlate with changes in nodule coverage and concentration. The acoustic backscatter has been measured for frequencies of 4.5, 9, 15, 28, 60, 112 and 163 kHz and grazing angles from normal incidence to 5 degrees. The backscatter increases as the square of the frequency for sediments.