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Recherche et développementpour la défense Canada Canada

DRDC Aspects of SW06 – 2007 Workshop

Sean Pecknold, Paul Hines, John Osler, Victor Young, and Dale Ellis

Maritime Environmental Awareness Group, DRDC Atlantic31 January, 2007

Defence R&D Canada – Atlantic • R & D pour la défense Canada – Atlantique

Outline

• Data acquired

– Propagation loss

– Swath bathymetry

– FFCPt

– WBS and WARBL

• Data needed

• Anticipated output/collaborative efforts

• Other results

Defence R&D Canada – Atlantic • R & D pour la défense Canada – Atlantique

Propagation loss

• Sources

– MSM

– Shipboard projector

• CWs, 200 Hz LFMs @ 1.2 and 3 kHz

• Receivers

– 2 GPS enabled SBs

– Moored UAT – 8 h/p between 22 m and 51 m depth – 24kHz sampling rate

Defence R&D Canada – Atlantic • R & D pour la défense Canada – Atlantique

Propagation loss runs

38.9

39

39.1

39.2

39.3

39.4

-73.40 -73.30 -73.20 -73.10 -73.00 -72.90 -72.80 -72.70WBS (bottom)

Current moorings

New ADCP

cHIRPS

BBNs

Mooring lines

UATdep

FFCPT drops

sonobuoys

BBNs

ADCP

39.01.176N 73.03.276W

39.07.170N 73.16.638W

39.13.182N 72.54.462W

Defence R&D Canada – Atlantic • R & D pour la défense Canada – Atlantique

Local measurements

Next Figure

2000 m

Reson 8125

• 455 kHz, 120 metre range

• 240 cross-track beams (0.5º)

• 1º along-track beam width

• 6 mm depth resolution

• DGPS, Gyro, pitch-roll-heave

• Pole mount on Quest

Hull mounted EdgeTech X-Star Chirp Profiler (2-16 kHz)

Defence R&D Canada – Atlantic • R & D pour la défense Canada – Atlantique

Defence R&D Canada – Atlantic • R & D pour la défense Canada – Atlantique

XSV Aug 1XBT Aug 1BBN Targets

Multiple drop FFCPT transectsseabed and water column measurements

0

10

20

30

40

50

60

70

80

1470 1480 1490 1500 1510 1520 1530

Sound speed (m/s)

Dep

th (

m)

.

CTD 2

CTD 3

CTD 4

CTD 5

CTD 6

CTD 7

CTD 8

CTD 9

CTD 10

CTD 11

CTD 12

CTD 13

CTD 14

Defence R&D Canada – Atlantic • R & D pour la défense Canada – Atlantique

Initial scattering results from SW06

SW06 Energy Time Series – in process of calibration

Strataform ScatteringStrength Result

Hines et al., (2005)

Defence R&D Canada – Atlantic • R & D pour la défense Canada – Atlantique

Wide Angle Reflection and Bottom Loss

• Bottom loss is the angle-fitted source level, calculated from direct arrival, minus received level minus theoretical transmission loss from a perfectly reflecting bottom (technique of Holland and Osler, 2000).

BL = SL - RL - TL

RECEIVER

DIRECT SOURCE

BOTTOM REFLECTED

Range

Time

1-12 kHz source

FFCPt1

FFCPt2

WBS July 24

WBS July 25

sonobuoys

Defence R&D Canada – Atlantic • R & D pour la défense Canada – Atlantique

Data needed

• Sensor data from moorings (23 July – 2 August)

• Shipboard met data, CTDs/XBTs (available on DVD)

• Other acoustic data from 25 July – 2 August; ambient noise and propagation (available from WHOI)

• MSM source levels

• Sediment acoustic properties

– Chirp runs along propagation paths/WBS area (Turgut)

– Sediment mapping (Miller)

• Roughness measurements (IMP) in APL-UW area (Tang)

• Core data from FFCPt drop areas for comparison

Defence R&D Canada – Atlantic • R & D pour la défense Canada – Atlantique

Anticipated output/collaborative efforts

• Scattering strengths and roughness, with Tang

• Analysis of WARBL data for bottom loss at varying angles and comparison w. Dahl

• Comparison of FFCPt measurements to inversion results (Chapman and others)

• Propagation sensitivity to oceanographic and geoacoustic parameters, with Dosso (UVic)

• Improvement of model predictions based on REA – 2007 Maritime Acoustic Symposium (CFMWC/METOc)

Defence R&D Canada – Atlantic • R & D pour la défense Canada – Atlantique

Other results

• Successful REA operation with reachback to DRDC

• Auralization data from BBN targets

• In-air vs. in-water sound levels for Convair flyover

• Ship noise levels

Defence R&D Canada – Atlantic • R & D pour la défense Canada – Atlantique

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