What question did this study set out to answer?

To measure acoustic bottom and subbottom reflections in the Canada Basin of the Arctic Ocean over one year.

May 14, 2026

Low-frequency bottom and subbottom reflections in the Arctic Ocean

Key Points

To measure acoustic bottom and subbottom reflections in the Canada Basin of the Arctic Ocean over one year.
Analyzed data recorded by the Scripps Institution of Oceanography at a 4000 m deep mooring.
Utilized a vertical array of hydrophones and a sound source to capture reflections from the bottom and subbottom layers.
Normal bottom reflection loss was approximately 13.5 dB with annual variation.
First subbottom return may indicate free gas beneath a hydrate layer, and third return showed strong variability in both travel time and amplitude.

Abstract

Using data recorded and made available by the Scripps Institution of Oceanography, acoustic bottom reflection beneath a mooring in the Canada Basin of the Arctic Ocean was measured over a period of 1 year. The data were collected at a mooring in a water depth of 4000 m, which contained a sound source and a vertical array of hydrophones. The latter was used to form up and down-looking end-fire arrays. Reflections from the bottom and three subbottom layers were detectable. The sound path between the array and the bottom was very stable consistent with a very homogeneous water mass below 400 m called the Canada Basin Deep Water. The normal bottom reflection loss was approximately 13.5 dB, with a small annual sinusoidal variation. The subbottom returns were less stable. The first subbottom return may be due to free gas beneath a stable hydrate layer. The third subbottom return was very strong and variable in both travel time and amplitude. Work supported by the US Navy’s Office of Naval Research, Code 322OA, grant N00014-23-1-2522.

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