Cross-hole acoustic tomography of Arctic sea ice: insights into temperature-driven velocity and attenuation variations

Abstract Sea ice, as a complex and highly variable medium covering the ocean surface, exhibits intricate internal structural variations that significantly affect the ocean’s thermodynamic, dynamic, and acoustic properties. However, the extreme conditions of the polar environment pose major challenges for conducting in-situ surface experiments, resulting in limited research on the acoustic structure of Arctic sea ice. This paper presents the results obtained from cross-hole acoustic measurements conducted during the 13th Chinese National Arctic Research Expedition. A traveltime tomography method is employed to invert the acoustic velocity distribution within sea ice. The Dijkstra algorithm is used for ray tracing, and damped least-squares inversion is applied to enhance solution stability and control ray path curvature to model acoustic wave propagation paths accurately. Additionally, the attenuation characteristics of sea ice are analyzed by monitoring changes in signal amplitude. This study also investigates the influence of temperature on sound speed and amplitude. The findings of this work contribute valuable insights to future studies on sea ice-climate interactions and acoustic wave propagation in polar ocean environments.