Phase variations in short-range transmissions produced by cyclonic eddies
Robert F. Henrick, Melvin J. Jacobson, William L. Siegmann · The Journal of the Acoustical Society of America · 1979
Mesoscale cyclonic eddies are characterized by cores of low sound speed and counterclockwise rotational currents. These effects are approximated using a parametric eddy model [J. Acoust. Soc. Am. 62, 860–870 (1977)] derived by the authors. Their influence on acoustic phase variations in short-range propagation between a surfaced source and receiver is studied using ray theory. In contrast to previous acoustic investigations, eddies of arbitrary size and strength are considered, effects of both currents and horizontal and vertical sound-speed variations are incorporated and arbitrary position and orientation of the source and receiver within the eddy are permitted. Currents are shown to be responsible for up to 20% of the total phase variation, indicating their importance in eddy-acoustics problems. Significant differences in phase variations resulting from changes in source-receiver location and orientation, in an eddy of fixed size and strength, are demonstrated. Then, general results are presented to illustrate how phase variation depends on parameters characterizing eddy size and strength. [Work supported by ONR.]