Acoustic inference of sea ice mechanical properties using flexural wave phase speed dispersion generated by coherent sources

Arctic environmental trends are important regionally and globally, in terms of effects on commercial activities, native coastal communities, and global temperatures and sea level. The Arctic energy budget is driven by atmospheric temperatures, cloud cover, wind patterns, freshwater discharge, oceanic forcing and sea ice cover. Sea ice cover is particularly important because it buffers air-sea heat flux and strongly influences Earth’s absorption of solar radiation through the ice-albedo feedback mechanism. Understanding the relative contributions of all these factors to the Arctic environment is challenging; our observations and modeling are incomplete. To that end, work in the 1980s demonstrated that mechanical properties of Arctic sea ice can be inferred by observation of the speeds of compressional, shear and flexural waves generated through in-ice conversion of impulsive energy. The work presented here (a) advances the work from the 1980s and 1990s by making use of coherent sources with which broadband signals can be generated to replace the manually generated hammer-drop signals, leveraging processing gain and improving temporal resolution via matched filter; and (b) demonstrates the potential for remote, autonomous monitoring of sea ice mechanical properties via acoustic inference based on observed flexural wave phase speed dispersion in the ice sheet in the Beaufort Sea.