Inferring first-year sea ice thickness using broadband echosounders

• Published in: The Journal of the Acoustical Society of America Vol. 144; no. 3; p. 1819
• Main Authors: Bassett, Christopher, Lavery, Andone C., Wilkinson, Jeremy P., Maksym, Ted, Courville, Zoe R.
• Format: Journal Article
• Language: English
• Published: 01-09-2018
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.5068024

Sea ice thickness is sparsely observed in situ. Under-ice acoustic techniques are a useful, but are generally used measure ice draft as a proxy for ice thickness. Using measurements of broadband acoustic backscattering (75–130 kHz) from laboratory-grown sea ice up to 80 cm thick, individual echoes from the water-ice and ice-air interfaces were isolated. Using the time delay between the echoes and a sound speed profile in the ice, total thicknesses were inferred and agree well with lengths of ice cores. This approach requires no ancillary data (i.e., water sound speed or pressure measurements). A temporal-domain model combining backscattering from both interfaces and from bubbles suspended within the brine channels also compares favorably with the measurements. This model is used to study the feasibility of applying the technique to first-year sea ice and to identify the bandwidths that best balance the constraints imposed by the scattering physics and practical considerations.