Direct inference of first-year sea ice thickness using broadband acoustic backscattering

Area of Science:

• Geophysics
• Climate Science
• Oceanography

Background:

• Accurate sea ice thickness measurements are crucial for climate change research, maritime safety, and Arctic community resilience.
• Current methods for measuring sea ice thickness are often invasive (ice cores) or indirect (altimetry, sonar, electromagnetic techniques), limiting regular, widespread assessment.
• Remote sensing of sea ice thickness remains a significant challenge in polar regions.

Purpose of the Study:

• To explore the viability of broadband acoustic techniques as an alternative method for measuring total sea ice thickness.
• To develop and validate a time-domain acoustic model for sea ice thickness estimation.
• To investigate optimal acoustic frequencies for in situ sea ice thickness measurements.

Main Methods:

• Laboratory-grown sea ice samples were used to compare acoustic thickness estimations with traditional ice core measurements.
• A time-domain acoustic model was developed to simulate scattering mechanisms and invert echo time delays (water-ice and ice-air interfaces) for thickness.
• Experimental measurements were compared with model predictions to validate the acoustic technique.

Main Results:

• Acoustic thickness estimations derived from the time delay between water-ice and ice-air echoes showed good agreement with ice core measurements.
• The developed time-domain model accurately captured dominant scattering mechanisms relevant to sea ice.
• The acoustic method successfully decoupled sea ice thickness estimates from variations in water column properties.

Conclusions:

• Broadband acoustic techniques show significant promise for accurate, non-invasive measurement of total sea ice thickness.
• This method offers an alternative to traditional techniques and can potentially be integrated with ice draft measurements.
• Further research into optimal frequencies can enhance the in situ application of acoustic sea ice thickness monitoring.