The Long-range Ocean Acoustic Propagation EXperiment (LOAPEX): An overview

Abstract

The Long-range Ocean Acoustic Propagation EXperiment (LOAPEX), conducted in the NE Pacific Ocean, provided acoustic transmissions from a ship-suspended source at eight widely separated stations, and from a cabled acoustic source near the Island of Kauai, HI. The transmissions were received on several bottom-mounted horizontal hydrophone arrays distributed about the NE Pacific Ocean Basin and two, nearly colocated, vertical hydrophone line arrays spanning roughly 3500 m of the water column. Ranges varied from 50 km to several Mm. The goals of the experiment are (i) to study the evolution, with distance (range), of the acoustic arrival pattern and in particular the dependence of the spatial and temporal coherence; (ii) to investigate the nature of the deep caustics and the associated arrivals well below their turning depths; (iii) to analyze the effects of the ocean bottom near the bottom-mounted acoustic source cabled to Kauai; and (iv) to produce a thermal snapshot of the NE Pacific Ocean. The experiment goals, design, and methods are described as well as preliminary data results. [Work supported by ONR.]