Calibration and application of high-frequency submersible sub-bottom profiler for deep-sea surficial sediment measurement.

We developed a high-frequency submersible sub-bottom profiler (HF-SSBP) instrument for taking deep-sea sediment measurement. In order to evaluate the reliability of profile data, a laboratory calibration method (LCM) was developed using illuminated acrylic standard boards in anechoic tank to form multi-layer reflections and evaluate the errors of the HF-SSBP. Two layer reflections induced by single boards in different thicknesses and ranges were performed and recorded, after which four layer reflections induced by two boards with an adjusted water crack were set and logged. The results showed that the HF-SSBP resolution was 44.9 mm in acrylic and its equivalent in the sediment was 28.5 mm. The absolute measure error was 7 mm with an acrylic board thickness of 100 mm, and the maximum measure error was 3.5 mm in different water thicknesses. As a test and application, deep-sea sediment measurement of the HF-SSBP was launched and compared with in situ sampling cores in the same site. The measurement thickness for sections A and B are 39.4 cm and 23.2 cm, respectively, corresponding to the sampling core of 39.8 cm and 23.7 cm. The two results are close as we expected. This work demonstrates the reliability and accuracy of the HF-SSBP measurement, thus providing a good choice for deep-sea submergence vehicles to carry this sonar instrument to obtain high-resolution stratum in deep-sea surficial sediments. [ABSTRACT FROM AUTHOR]