Environmental correlates of Arctic ice-edge noise

Temporal variations of low-frequency, broadband ambient noise measured in early summer under drifting ice floes of the marginal ice zone (MIZ) are cross correlated with local environmental forces and ice field descriptors. Surface gravity wave forcing is the primary correlate of the noise; its interaction with ice floes generates ound, most likely via flexural floe failure, and unloading motion, within a few kilometers of the ice edge. Ice concentration is also well correlated with the noise, most likely parametrically. That is, as ice concentration increases, so does the density of potential sound sources in the ice field. Ice stress, ice moment, and wind stress magnitude, while highly correlated with low-frequency noise in the fully icecovered Arctic, are poor correlates in the MIZ. Lateral melt rate, as a surrogate for thermally induced ice stress, is also poorly correlated with low-frequency MIZ noise. When surface wave forcing is weak, about 1/2 the time in this experiment, episodes of high noise are sometimes observed. These episodes are roughly 3-6 h in duration and 12 h in periodicity. Evidence suggests hat they are related to the formation and advection of bands of highly concentrated ice by internal waves during off-ice winds.