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Underwater radiated noise levels of a research icebreaker in the central Arctic Ocean
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10.1121/1.4790356
/content/asa/journal/jasa/133/4/10.1121/1.4790356
http://aip.metastore.ingenta.com/content/asa/journal/jasa/133/4/10.1121/1.4790356
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

Bathymetric map of the area for measurements of U.S. Coast Guard Cutter Healy in the deep water (>3000 m) Arctic Ocean. Sonobuoy deployments are indicated by black squares and the depth contour interval is 250 m. Data provided by the International Bathymetric Chart of the Arctic Ocean ( Jakobsson et al., 2008 ).

Image of FIG. 2.
FIG. 2.

Sound speed profile (left) and ray path diagram (right) used to estimate launch angles for the bottom-bounce and direct path intersection at the sonobuoy depth. The horizontal range at which this occurs allows derivation of the slant range for transmission loss modeling.

Image of FIG. 3.
FIG. 3.

(Color online) During transit in variable ice cover on August 27, 2008: (A) Healy's ship track (gray line) relative to the sonobuoy deployment (small black circle), range estimate of the sonobuoy to the ship (large circle), as well as position and heading of Healy at 05:58:40 (arrow). The sonobuoy drifted with speeds over 1 knot (0.5 m/s), depending on surface currents, wind, and pack ice dynamics. Coordinate system origin is at 81° 42.82′N, 143° 59.65′W. (B) Images every 5 min (time in upper left corner) from the Aloft-Conn camera provide an estimate of local sea ice coverage (×/10 in upper right corner).

Image of FIG. 4.
FIG. 4.

During August 27 transit: (A) vessel speed-over-ground (solid) and propeller shaft rotational speeds (starboard = dashed; port = dotted). (B) Source level estimates (dB re: 1 μPa at 1 m) centered around 55.6 Hz (49–62 Hz band) for 1/3 octave band and 56.6 Hz (40–80 Hz band) for 1-octave band. Sea ice coverage estimates are shown at 5-min intervals along the top of the graph.

Image of FIG. 5.
FIG. 5.

During August 27 transit: (A) estimated source level of Healy transiting in 8/10’s ice cover at 05:26:30; range to the sonobuoy was approximately 2 km. (B) Estimated source level of Healy transiting in 3/10’s ice cover at 05:51:20; range to the sonobuoy was approximately 4 km.

Image of FIG. 6.
FIG. 6.

(Color online) During backing-and-ramming operations on August 28, 2008: (A) ship track (gray line) relative to the sonobuoy deployment (small black circle), range estimate to the sonobuoy (large circle), as well as the position and heading of Healy at 23:10:10 (arrow). Coordinate system origin is at 82° 3.73′N, 142° 28.40′W. (B) Images every 5 minutes (time in upper left corner) from the Aloft-Conn camera estimate local sea ice coverage (×/10 in upper right corner).

Image of FIG. 7.
FIG. 7.

During August 28 backing-and-ramming operations: (A) vessel speed-over-ground (solid) and propeller shaft rotational speed (starboard = dashed; port = dotted). (B) Source level estimates (dB re: 1 μPa at 1 m) centered around 11.3 Hz (10–13 Hz), 55.6 Hz (49–62 Hz), 111 Hz (98–123 Hz), 1.12 kHz (0.985–1.24 kHz), and 11.3 kHz (9.93–12.5 kHz) for 1/3 octave bands, respectively. Spectral estimates for full octave bands are centered around 14.1 Hz (10–20 Hz), 56.6 Hz (40–80 Hz), 113 Hz (80–160 Hz), 0.905 kHz (0.640–1.28 kHz), and 7.24 kHz (5.12–10.24 kHz), respectively. The ship was consistently in 8/10’s ice cover.

Image of FIG. 8.
FIG. 8.

(Color online) During backing-and–ramming on August 28–29, 2008: (A) ship track (gray line) relative to the sonobuoy deployment (small black circle), range estimate to sonobuoy (large circle) as well as the position and heading of Healy at 00:25:00 (arrow). Coordinate system origin is at 82° 3.27′N, 142° 30.27′W. (B) Images every 5 min (time in upper left corner) from the Aloft-Conn camera estimate local sea ice coverage (×/10 in upper right corner).

Image of FIG. 9.
FIG. 9.

During backing-and-ramming on August 28–29: (A) vessel speed-over-ground (solid) and propeller shaft rotational speed (starboard = dashed; port = dotted). (B) Source level estimates (dB re: 1 μPa at 1 m) centered around 55.6 Hz (49–62 Hz), 111 Hz (98–123 Hz), and 1.12 kHz (0.985–1.24 kHz) for 1/3 octave bands, respectively. Spectral estimates for full octave bands are centered around 56.6 Hz (40–80 Hz band), 113 Hz (80–160 Hz band), and 0.905 kHz (0.640–1.28 kHz band), respectively (gray section indicates loss of acoustic data). The ship was in consistent 9/10's ice cover.

Image of FIG. 10.
FIG. 10.

(Color online) During deep-sea dredging operations on August 31, 2008: (A) ship track (gray line) relative to the sonobuoy deployment (small black circle), sonobuoy range estimate (large circle) as well as the position and heading of Healy (arrow). Coordinate system origin is at 81° 24.14′N, 151° 58.40′W. (B) Images every 5 min (time in upper left corner) from the Aloft-Conn camera estimate sea ice coverage (×/10 in upper right corner).

Image of FIG. 11.
FIG. 11.

Source level of Healy on August 31, while using its bow thruster in 9/10's ice cover; range to the sonobuoy was approximately 500 m.

Image of FIG. 12.
FIG. 12.

Source levels averaged from the August 27–29 recordings, together with the ship's port and starboard propeller shaft speeds (RPM) as (A) two-dimensional plot and (B) three-dimensional plot. The point-size increases and the color of each point changes (scale bar on right) in 5 dB increments. The ship frequently transitioned from reverse to forward motion, and the propeller shaft rotation quickly changed direction.

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/content/asa/journal/jasa/133/4/10.1121/1.4790356
2013-04-03
2014-04-18
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Underwater radiated noise levels of a research icebreaker in the central Arctic Ocean
http://aip.metastore.ingenta.com/content/asa/journal/jasa/133/4/10.1121/1.4790356
10.1121/1.4790356
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