Relating Arctic ambient noise to thermally induced fracturing of the ice pack

Abstract

Thermally induced stresses within pack ice floes are simulated using a viscoelastic model that accounts for the time variation of the atmospheric forcing parameters and the temporal and spatial variations of snow cover. To relate the model-predicted stresses to the observed 500 Hz under-ice noise variations, a fracturing paradigm was developed. The fracturing paradigm includes factors related to ice tensile strength given its salinity and temperature and stress relief as a result of fracturing. A fracture count time history was produced using the thermal stress model and the fracturing paradigm for the fall of 1988 in the eastern Arctic Ocean. The results were compared with the observed 500-Hz noise. The fracture count shows increases for 11 of 13 under-ice noise episodes. Most of the observed under-ice noise episodes were of the type identified in previous studies; i.e., those associated with nightly cooling. In addition, this study identifies under-ice noise episodes related to longer-term occurrences associated with sustained cooling over several days after the passage of a cold front.