SOFAR propagation conditions in the Subarctic Northeast Pacific Ocean

Abstract

An analysis of two extensive sound speed profile surveys (winter and summer) of the subarctic region (above 40° N) in the Northeast Pacific Ocean shows that the depth of the deep sound channel axis is symmetric about the Alaskan Gyre (centered at 53° N, 153° W). The axis depth ranges from 100 m or less in the Gyre to 400 m or more along the coast of North America. A model for axis depth contours is developed which has some interesting results. For example, a north-south track along 140° W has little change of axis depth with latitude, while an east-west track along 53° N would have a significant change in axis depth. An estimate of the yearly variability of the model is made from long-term oceanographic data obtained at weather station “Papa” (50° N, 145° W). Sound propagation loss is computed for selected tracks using a range-dependent acoustic prediction model and these results are compared to experimental data.