An extended surface target for high-frequency multibeam echo sounder calibration.

Area of Science:

• Marine geophysics
• Acoustic oceanography
• Seafloor characterization

Background:

• Accurate intensity calibration is vital for multibeam echo sounders (MBES).
• Existing calibration methods may lack extended surface targets suitable for MBES.
• Seafloor backscatter data quality depends on precise instrument calibration.

Purpose of the Study:

• To develop and evaluate an extended calibration target for MBES intensity output.
• To assess the target's performance in calibrating a 200 kHz MBES.
• To validate MBES backscatter measurements using the new calibration tool.

Main Methods:

• Construction of a chain-link curtain-like target with a mean scattering strength of -17.8 dB at 200 kHz.
• Calibration of a 200 kHz MBES using the developed target.
• Collection of seafloor backscatter data over sand and gravel environments.
• Comparison of field results with calibrated split-beam echo sounder measurements at a 45° incidence angle.

Main Results:

• The chain-link target demonstrated a mean scattering strength of -17.8 dB at 200 kHz.
• The calibrated MBES successfully collected seafloor backscatter data.
• Field results showed good agreement when compared with split-beam echo sounder data.
• The extended target proved effective for MBES calibration.

Conclusions:

• The developed chain-link target is a viable tool for calibrating multibeam echo sounder intensity.
• This method enhances the reliability of seafloor backscatter measurements.
• The target facilitates more accurate acoustic surveys and seafloor mapping.