Measurements of near-surface bubble plumes in the open ocean with implications for high-frequency sonar performance

PDF

Authors
  1. Trevorrow, M.V.
Corporate Authors
Defence R&D Canada - Atlantic, Dartmouth NS (CAN)
Abstract
This study examines near-surface bubble data obtained with a self-contained 200-kHz inverted echo-sounder deployed at Ocean Station Papa (NE Pacific, 1400 km west of Vancouver Is.) over an 81-day period in the spring of 1996. The instrument operated continuously, recording calibrated volume scattering profiles from near-surface bubbles with 3-s and 30-cm resolution. The data show the frequent occurrence of bubbles organized into vertical, plume-like structures, presumably drawn downwards by turbulence and other near-surface circulations. Average bubble plume penetrations of up to 15 m were observed, with maximum penetrations up to 25 m. Within the plumes, the backscatter cross section exhibited an exponential decay with depth, with e-folding scale in the range 0.5 to 3 m, increasing proportionally to the square of average plume depth. Using standard models for bubble scattering, and incorporating recent acoustic resonator measurements of bubble-size distributions along with actual bubble plume data, high-frequency near-surface sonar performance models were developed. These models show that on a ping-to-ping basis the bubble plume structures can induce significant spatial variations in the reverberation level and path-integrated extinction losses to near-surface targets.
Report Number
DRDC-ATLANTIC-SL-2002-173 — Scientific Literature
Date of publication
03 Sep 2003
Number of Pages
13
Reprinted from
J. Acoust. Sco. Am, vol 114, no 5, 2003, p 2672-2684
DSTKIM No
CA034012
CANDIS No
533428
Format(s):
Document Image stored on Optical Disk

Permanent link

Document 1 of 1

Date modified: