Measurements of the travel-time bias caused by internal waves

Abstract

Theoretical work and computer simulations predict that the travel-time of acoustic signals is biased by the ocean internal wave field. The path integral theory for scattering predicts that the size of the travel time bias depends on the logarithm of the center frequency of the acoustic signal. A recent experiment, in which two acoustic signals with different center frequencies were transmitted simultaneously, makes it possible to measure the bias experimentally. Preliminary results suggest that the bias is about 50 ms at 3500-km range, which is roughly as large as expected. a)The AST group is T. G. Birdsall (U. Michigan), B. M. Howe (U. Washington), J. A. Mercer (U. Washington), K. Metzger (U. Michigan), R. C. Spindel (U. Washington), and P. F. Worcester (SIO).