Modeling of acoustic waveguides in floating ice sheets with vertical temperature profiles

The structure of Arctic sea ice is commonly simplified as a homogeneous plate for acoustic modeling. Under the influence of environmental factors, with temperature being the most critical, the acoustic characteristics of sea ice exhibit spatiotemporal variations. In this work, the variation in propagation velocity caused by differences in the upper and lower surface temperature of Arctic sea ice is considered through the virtual stratification of a leaky waveguide. An empirical model is established using experimental observations relating propagation velocity with temperature. To balance accuracy against flexibility, a nested matrix method is developed, incorporating the air-ice-water structure, formed with physical interfaces, and the vertical temperature change, represented by virtual stratification in ice. The model is validated against numerical simulation results using a spectral element method, demonstrating the inadequacy of the monolayer model based on effective medium theory. Two stratification protocols, namely, equal thickness and equal velocity change, are proposed and tested using temperature data from Arctic sea ice, and their performance is analyzed for various numbers of virtual stratification sublayers. Having demonstrated the importance of including environmental impacts in the modeling of an elastic waveguide in sea ice, further improvements, such as the presence of a snow layer, are discussed.