A relationship between ocean circulation and volume reverberation in the subarctic northeast Pacific Ocean (Gulf of Alaska)

Abstract

Earlier investigations have shown a significant change in integrated scattering [J. A. Scrimger and R. G. Turner, J. Acoust. Soc. Am. 54, 483–493 (1973)] and spectral characteristics [R. P. Chapman et al., J. Acoust. Soc. Am. 56, 1722–1734 (1974)] when transmitting into the subarctic (above 40 north latitude) northeast Pacific Ocean. An analysis of an extensive series of volume reverberation measurements obtained by Turner indicates a strong influence of the counterclockwise circulation around the Alaskan Gyre on the distribution of scattering strengths. At higher frequencies (5–20 kHz) the greater scattering strengths are found in the relatively warm California undercurrent water which flows around the perimeter of the gyre. At lower (1.25–5 kHz) frequencies the greater scattering strengths are found in the relatively cold water such is found in the upwelled subarctic water at the center of the gyre. This implies a significant change in the type of scatterers between these frequency domains. [Work supported by ONT and DREP.]