ASA 126th Meeting Denver 1993 October 4-8

1pAO10. Relating Arctic ambient noise to thermally induced fracturing of the pack ice---An ability to monitor climate change?

James K. Lewis

Atlantic Appl. Res. Corp., 207 S. Seashore Ave., Long Beach, MS 39560

Thermally induced fracturing of pack ice can be simulated using a viscoelastic model and a fracturing paradigm for predicting the stress state of the ice. Under a given set of circumstances, the fracturing paradigm simulates conditions that exceed the tensile strength of the ice as well as the associated stress relief as a result of fracturing. The thermal stress--ice fracturing model was used to produce a fracture count time history for the ice pack during the fall of 1988 in the eastern Arctic Ocean. The count was compared to the observed 500-Hz under-ice noise in which 13 distinct noise episodes were identified. The simulation showed increases in predicted fracturing levels for 11 of the 13 noise episodes. Some of the fracturing was associated with nightly cooling. Others occurred as a result of sustained cooling over several days following the passage of cold fronts. The stress--fracturing model can be used to study changes in under-ice noise as a result of global warming. Examples are presented based on warming as predicted by various climate models. The results indicate that climate changes could be monitored using winter-time under-ice ambient noise observations from the Arctic.