Glider-based seabed characterization using natural-made ambient noise

Abstract

Seabed characteristics (geoacoustic properties and scattering strength) are critical parameters for sonar performance predictions. However, this bottom information is considered very difficult and expensive to achieve in the scientific community. In this report, an efficient method for inferring the seabed properties is presented; it relies on a previous methodology using long moored or drifting hydrophone arrays. Results from sea trials demonstrate the feasibility of using the technique by deploying a hybrid autonomous underwater vehicle hosting a unique hydrophone array consisting of a five-element vertical line array and a four-element tetrahedral array. Seabed reflection and layering properties are estimated from sea surface generated ambient noise acquired during two trials in different shallowwater areas. Results from numerical modeling, data analysis and experimental measurements are presented with emphasis on comparing the seabed characterization at different locations with different bottom properties. The results obtained from both experiments demonstrate the potential of using autonomous underwater vehicles for seabed characterization and surface vessel tracking.

Tertiary Waves Measured during 2017 Pohang Earthquake Using an Underwater Glider

“…Among these platforms, underwater gliders have been actively used for measurement of environmental underwater ambient noise. The addition of a single hydrophone sensor to an underwater glider provides a capability for measurement of underwater noise level [7][8][9][10][11][12][13][14] and the addition of a hydrophone array enables surveillance of the underwater acoustic environment [15,16].…”