Long‐range acoustic transmission in the northwest Atlantic

An acoustic propagation experiment conducted west of Bermuda during the fall of 1978 demonstrated that individual acoustic arrivals at 900‐km range were stable and identifiable over a 48‐day period. The observed arrival pattern is interpreted by geometric ray theory and by comparison with a ‘synthetic sofargram’ (equivalent to a synthetic seismogram) constructed from WKBJ theory. Using geometric ray theory, we examine the expected generation and annihilation of ray paths as a result of the seasonal erosion of the autumnal thermocline. Many rays are converted from purely refracted to surface reflected/refracted rays. The ultimate goal of this work is to interpret variability in acoustic transmission in terms of ocean variability.