ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

1aAO7. Long-distance low-frequency modal propagation into the Lincoln Sea.

Rich Pawlowicz

Inst. of Ocean Sci., P. O. Box 6000, Sidney, BC V8L 4B2, Canada

David M. Farmer

Inst. of Ocean Sci., Sidney, BC V8L 4B2, Canada

Barbara Sotirin

NCCOSC-RDTE, San Diego, CA 92152-5000

Siobhan Sozard

Univ. of Victoria, Victoria, BC, Canada

One-Mm transmissions from the April 1994 trans-Arctic acoustic propagation (TAP) experiment recorded by a vertical line array deployed from an icecamp at the edge of the continental shelf in the Lincoln Sea are analyzed. The received phase is astonishingly stable, and appears to vary mainly with source/receiver motions. Travel times determined from M-sequence transmissions are less stable and are not consistent with the phase measurements. Modal decomposition shows that bottom effects strip out the higher-order modes as sound propagates onto the shelf. The amplitude of the surface-trapped first mode is also weaker than predicted by standard loss mechanisms. Some implications of this analysis for the design of future Arctic low-frequency tomography experiments are discussed.