High-frequency broadband acoustic current tomography in shallow water

Abstract

To study current tomography in very shallow water regions a simultaneous oceanographic and broadband (1-25 kHz) acoustic experiment was conducted in the Delaware Bay. The mean water depth was 15 m and the source-receiver range was 760 m. In this paper, we discuss the feasibility of using reciprocal acoustic transmission for current tomography applications. A beamforming technique is used to resolve the arrival time of direct and surface-bounced rays since in shallow water the received acoustic signals are more complicated due to multiple interactions with bottom and sea surface. Using the experimental data, the accuracy of travel time measurements for variable environmental conditions is examined for different center frequencies and bandwidths. The current velocity prediction results are compared with ADCP measurements to determine the feasibility of current tomography in shallow water.