Amplitude and phase front variations for individual modes in Shallow Water 2006 Experiment.

Abstract

Using modal selection techniques, developed for an L‐shaped array, the amplitude and phase front variations for individual modes are considered for shallow water waveguides in the presence of internal waves (IWs). Experimental data collected during the Shallow Water 2006 Experiment include acoustic transmissions during several IW events. In this paper, we focus on one of these IW episodes (i.e., event 50) where a train of nonlinear IW was moving approximately across an acoustic track. Low‐frequency LFM signals with band 270–330 Hz were transmitted from a source moving with the advancing IW front and were received by an L‐shaped array for few hours. During this time, the angle between the acoustic track and the IW front changed while transmissions continued. The waveguide in the presence and the absence of a train of IW was observed providing excellent environmental input for modeling. Fluctuations of the intensity as well as the modal phase are studied using experimental data and modeling of the waveguide during this period. [Work supported by ONR321OA and CRDF].