Arctic Ocean Noise Generation Due to Pack Ice Kinematics and Heat Fluxes

Abstract

Noise, ice motion, and a heat flux model are used to study the generation of arctic ambient noise under pack ice. During the summer, observations indicate that most under-ice noise is generated by the ice rushing through the water. Differential ice motion appears to be insignificant in producing ambient noise. This situation changes by fall when the total deformation of the pack ice becomes important in producing lower frequency noise (10 and 32 Hz). Correlations indicate that differential motions of other forms (primarily ice convergence) become important only during winter. As for higher frequency noise (1000 Hz) during fall and winter, correlations with ice motion are low and ambiguous. The generation of higher frequency noise by the combination of ice motion and thermal microfracturing is the likely cause of the seemingly sporadic nature of this frequency band. Anomalous observations are presented which are investigated using a variety of environmental data sets. A model of thermal heat flux within a slab of ice is used to demonstrate the character of one set of observations. However, there are distinct deficiencies in that the model fails to reproduce the phase of the thermal microfracturing and certain periods during which microfracturing is absent.