Arctic Marine Acoustics.

• Main Author: Kutschale,H W
• Other Authors: LAMONT-DOHERTY GEOLOGICAL OBSERVATORY PALISADES NY
• Format: Text
• Language: English
• Published: 1984
• Subjects: Acoustics; *SOUND TRANSMISSION; ROUGHNESS; UNDERWATER SOUND; OCEAN BOTTOM; SEA ICE; SONAR PULSES; ARCTIC OCEAN; UNDERICE; SOFAR(Sound Fixing and Ranging); Arctic; Arctic Ocean; Sea ice
• Online Access: http://www.dtic.mil/docs/citations/ADA147492; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA147492

Wave-theoretical computer codes have been developed to model pulse propagation in the central Arctic Ocean. Pulse shapes as a function of range and depth are computed from the Pulse Fast Field Program (PFFP) and the pulse parabolic equation (PPE) code. Group- and phase-velocity dispersion and eigenfunctions are computed from the PFFP or from a corresponding normal-mode program. Good agreement has been obtained between measured and computed SOFAR signals. The effect of ice roughness on Arctic SOFAR propagation is illustrated from field data and the PFFP. Hydroacoustic signals from underwater explosions that have propagated over the Arctic abyssal plains commonly display marked frequency dispersion in pulses that are bottom-interacting and that arrive after the SOFAR signal. In the infrasonic band of 2 to 20 Hz, the temporal dispersion for each pulse that has interacted with the flat bottom of the plain can be nearly as strong as that observed in the SOFAR signal for the first mode. However, the bottom-interacting pulses correspond to a coherent summation of many higher-order normal modes in a channel bounded above by the ocean surface and below by the zone of increasing velocity in the upper 400 m of the bottom sediment.