VERTICAL NOISE COHERENCE MEASUREMENTS IN SHALLOW WATER USING LAGRANGIAN DRIFTERS

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Authors
  1. Desharnais, F.
  2. MacDonald, B.R.
  3. Mah, K.J.
Corporate Authors
Defence Research Establishment Atlantic, Dartmouth NS (CAN)
Abstract
The vertical coherence of an acoustic noise field in shallow water (at frequencies dominated by sea surface noise) can be used to infer certain ocean bottom properties such as the compressional sound speed of the upper sediment layer. Three Lagrangian Ambient Noise Drifters (LANDs) were developed for vertical coherence measurements. The drifters (drogued at 15 m depth) follow the near-surface currents, and take hourly measurements of coherence from their two hydrophones located at 50 m depth. The hydrophone separation is 1 m, and the measurements are made over a useable frequency range of 100 Hz to 1 kHz. The drifters were deployed twice consecutively at Western Bank (Scotian Shelf, Canada) and drifted for a period of up to 2.5 days.
Keywords
Vertical Coherence;Langrangian drifters
Date of publication
01 Feb 1998
Number of Pages
3
DSTKIM No
98-00621
CANDIS No
507466
Format(s):
Hardcopy;Document Image stored on Optical Disk

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