Simulation of acoustic reflection and backscatter from arctic sea-ice

Area of Science:

• Oceanography
• Acoustics
• Geophysics

Background:

• The Arctic ocean is rapidly warming, necessitating advanced methods for monitoring sea ice.
• Autonomous underwater vehicles equipped with upward-looking sonars present a viable solution for sea ice characterization.

Purpose of the Study:

• To investigate the potential of upward-looking sonar for characterizing Arctic sea ice.
• To analyze the relationship between acoustic signals and sea ice properties like thickness and mechanical characteristics.

Main Methods:

• Numerical simulations using wavenumber integration code were performed for sonar signals under smooth ice.
• Analysis of sonar frequency and bandwidth requirements for pulse-echo measurements.
• Simulations of acoustic reflection from rough water-ice interfaces.

Main Results:

• Significant information about sea ice properties can be extracted from acoustic signals, even in attenuating ice.
• Discrete resonance frequencies correlate with the shear wave speed-to-thickness ratio.
• Signal periodicity relates to compressional wave speed-to-thickness ratio, and decay rates indicate attenuation coefficients.
• Moderate sea ice roughness enhances acoustic signals, whereas high roughness degrades characterization.

Conclusions:

• Upward-looking sonar is a promising technology for monitoring Arctic sea ice.
• Acoustic signal analysis provides insights into sea ice thickness, mechanical properties, and attenuation.
• Sea ice surface roughness is a critical factor influencing the effectiveness of sonar-based characterization.