Path-Length Stability of the Ocean, Inferred from Ocean Temperature Measurements
JOHNS HOPKINS UNIV LAUREL MD APPLIED PHYSICS LAB
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In an extensive ocean test at the Atlantic Undersea Test and Evaluation Center AUTEC, fluctuations of acoustic path length were found to be no more than 0.001 meter rms for periods of 1 minute over a vertical path extending from an ocean depth of 60 to 320 meters. The measurements showed that the ocean is sufficiently stable to allow sophisticated coherent signal processing as would be necessary for synthetic aperture sonar at moderate frequencies 2OkHz. Path-length stability was inferred from continuous measurements of the ocean temperature profile determined by a 20-element temperature array suspended from a research vessel. Time-dependent temperature fluctuations remained after the recorded temperature was compensated for changes in depth of the array.
- Physical and Dynamic Oceanography
- Acoustic Detection and Detectors