Thin-ice Arctic Acoustic Window (THAAW)

Abstract

Abstract : The Arctic Ocean is currently undergoing dramatic changes, including reductions in the extent and thickness of the ice cover and extensive warming of the intermediate layers. The multiyear ice is melting. Ice keels are getting smaller. With more open water, the internal wave energy level and therefore acoustic volume scattering are likely increasing, at least during summer. What was learned about acoustic propagation and ambient noise in the Arctic during the Cold War is now obsolete. The long-term objectives of this research program are to understand the effects of changing Arctic conditions on low-frequency, deep-water propagation and on the low-frequency ambient noise field. The goal is to determine the fundamental limits to signal processing in the Arctic imposed by ocean and ice processes. The hope is that these first few new steps will lead to a larger, permanent acoustic monitoring, communications, and navigation network in the Arctic Ocean (Mikhalevsky et al., 2014). This research effort was funded as an expansion of ONR Grant N00014-12-1-0226, entitled North Pacific Acoustic Laboratory: Deep Water Acoustic Propagation in the Philippine Sea. This annual report is in addition to the annual report for ONR Grant N00014-12-1-0226 that describes the research effort in the Philippine Sea.