Preliminary Geoacoustic Inversion Results from SW06 Data

Ross Chapman

ONR Shallow Water Experiment 06 WorkshopJanuary, 30-31, 2007 San Diego, CA

University of Victoria, BC, Canada

ONR SW06 Workshop, January, 30-31, 2007 San Diego, CA

Low Frequency Geoacoustics (Knorr: Aug 23 – Sept 06)

- Bill Hodgkiss, Peter Gerstoft, Chenfen Huang (MPL)

- David Knobles et al (ARL)

- Ross Chapman, Yongmin Jiang, (UVic)

ONR SW06 Workshop, January, 30-31, 2007 San Diego, CA

Data sets used (at VLA1):• Low frequency tonals for 3 ranges along ‘DJ’ track• Chirps at fixed range

Objectives:• Geoacoustic model for common site

• Broad frequency band• Well surveyed range dependence

Approaches:• MFI for tonal signals

• single layer geoacoustic model• Reflection coefficient inversion of fixed range chirp data

ONR SW06 Workshop, January, 30-31, 2007 San Diego, CA

Example of matched field inversion result – parameter uncertainty estimates at WP21 (~ 1km)

75 80 85

WD: 79.466(m)

20 40 60

H: 44.168(m)

1400 1600 1800

cp1: 1574.828(m/s)

1600 1800 2000 2200 2400

cpb: 1648.879(m/s)

0.2 0.4 0.6 0.8

p1: 0.939(dB/m/kHz)

0.2 0.4 0.6 0.8

pb: 0.252(dB/m/kHz)

1.5 2 2.5

1: 1.933(g/cm3)

2 2.5 3

b: 2.532(g/cm3)

25 30 35

SD: 30.284(m)

0.5 1 1.5

Range: 1.164(km)

8 10 12 14

rdvb: 12.588(m)

1 1.5 2

fexp: 1.096

0 5 10

tilt: 1.207( )

0 50 100 150

Steer: 98.379( )

File: jd239lm00137; Date: 26-Jan-2007

ONR SW06 Workshop, January, 30-31, 2007 San Diego, CA

Example of data processing for reflectivity coefficient inversion – Fixed range high frequency chirps

• Sea floor & subbottom reflection at VLA1 site

• Sound speed and attenuation from 2000 ~ 4000 Hz

• Sound speed ~ 1580 m/s

ONR SW06 Workshop, January, 30-31, 2007 San Diego, CA

• Some problems with the data:• MFI: no information in some tonal frequencies• Significant variation in signal level• Significant variation in SSP• Array geometry: hydrophone depths uncertain?

• What other information do we need?• Chirp sonar track over DJ line; geoprobe data• Swell and wave direction & height• Source levels for LF and MF sound sources• ARL acoustic data from SWAMIs

• Preliminary low frequency geoacoustic model for ‘DJ’ track• sea floor sediment parameters over range dependent track• sediment sound speed: ~1600 m/s (50 – 900 Hz)

Collaborations for geoacoustics:- Geoacoustic models for broad frequency band for DJ track and Moray/VLA site- SWAMI site data-

ONR SW06 Workshop, January, 30-31, 2007 San Diego, CA

Collaborations for geoacoustics:- Geoacoustic models for broad frequency band for DJ track and Moray/VLA site:

MPL (LF < 4500 Hz) and APL (2 – 20 kHz)

- SWAMI site data: ARL- long and short range geoacoustic inversion at sandy site- expect less variation in SSP- LF and MF data (chirps)

- Experimental benchmark data set for inversion methods?

- Target a JASAEL collection of preliminary results (2007)?

- Hurricane Ernesto Noise data: SWAMIs

ONR SW06 Workshop, January, 30-31, 2007 San Diego, CA

Discussion Slides

ONR SW06 Workshop, January, 30-31, 2007 San Diego, CA

final energy of each frequency in optimization: 0.2338038 0.00363505 ( 53Hz) 0.21442491(103Hz) 0.56934798(203Hz) 0.40013963(253Hz) 0.57140428 (303Hz) 0.37056041(403Hz) 0.35731304(503Hz) 0.66464043(703Hz)

Energy Function:

F

F

ff mBmE

1

)()(

2)(

)(ˆ)()ˆ()(

mp

mpRmpRTrmB

f

fffff

ONR SW06 Workshop, January, 30-31, 2007 San Diego, CA

Range(km)

Dep

th(m

)

Maximum value of bartlett: 0.6419

File: jd239l00101; Date: 16-Jan-2007--"+" TRUE (0.9800km ,30.0m); "o" ESTIMATED (0.6500km ,71.5m); x=0.0100km, y= 0.8m

0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5

0

10

20

30

40

50

60

700.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

WD=79.5, Rdvb = 8.2m

Range(km)

Dep

th(m

)

Maximum value of bartlett: 0.6732

File: jd239l00101; Date: 16-Jan-2007--"+" TRUE (0.9800km ,30.0m); "o" ESTIMATED (0.6400km ,71.5m); x=0.0100km, y= 0.8m

0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5

0

10

20

30

40

50

60

70

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

WD=79.5m, Rdvb=11.8m

Range(km)

Dep

th(m

)

Maximum value of bartlett: 0.5367

File: jd239l00101; Date: 16-Jan-2007--"+" TRUE (0.9800km ,30.0m); "o" ESTIMATED (1.1200km ,29.2m); x=0.0100km, y= 0.8m

0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5

0

10

20

30

40

50

60

70

0.2

0.25

0.3

0.35

0.4

0.45

0.5

WD=78.8, rdvb =11.8m, 8fres

Range(km)

Dep

th(m

)

Maximum value of bartlett: 0.4593

File: jd239l00101; Date: 16-Jan-2007--"+" TRUE (0.9800km ,30.0m); "o" ESTIMATED (0.6800km ,73.3m); x=0.0100km, y= 0.8m

0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5

0

10

20

30

40

50

60

70

0.2

0.25

0.3

0.35

0.4

WD=78.8, rdvb =8.2m, 8fres

ONR SW06 Workshop, January, 30-31, 2007 San Diego, CA

Range(km)

Dep

th(m

) Maximum value of bartlett: 0.4350

File: jd239l00101; Date: 17-Jan-2007--"+" TRUE (0.9800km ,30.0m); "o" ESTIMATED (0.6200km ,69.3m); x=0.0100km, y= 0.8m

0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5

0

10

20

30

40

50

60

70

0.15

0.2

0.25

0.3

0.35

0.4

WD=78.8, rdvb =9.05m, 8fres

Range(km)

Dep

th(m

)

Maximum value of bartlett: 0.4666

File: jd239l00101; Date: 18-Jan-2007--"+" TRUE (0.9800km ,30.0m); "o" ESTIMATED (0.6900km ,72.5m); x=0.0100km, y= 0.8m

0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5

0

10

20

30

40

50

60

70

0.2

0.25

0.3

0.35

0.4

WD=78.8, rdvb =8.55m, 8fres

Range(km)

Dep

th(m

)

Maximum value of bartlett: 0.6832

File: jd239l00101; Date: 16-Jan-2007--"+" TRUE (0.9800km ,30.0m); "o" ESTIMATED (0.6200km ,70.9m); x=0.0100km, y= 0.8m

0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5

0

10

20

30

40

50

60

70

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

WD=78.8, rdvb =11.8m, wp21 ssp

Range(km)

Dep

th(m

)

Maximum value of bartlett: 0.6662

File: jd239l00101; Date: 16-Jan-2007--"+" TRUE (0.9800km ,30.0m); "o" ESTIMATED (0.6200km ,70.8m); x=0.0100km, y= 0.8m

0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5

0

10

20

30

40

50

60

70

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

WD=78.8, rdvb =11.8m, wp22 ssp

ONR SW06 Workshop, January, 30-31, 2007 San Diego, CA

WD=78.8, rdvb =11.8m, WP22 WD=78.8, rdvb =8.2m, WP22

WD=81.0, rdvb =11.8m, WP23 WD=81.0, rdvb =8.2m, WP23

Range(km)

Dep

th(m

)

Maximum value of bartlett: 0.5053

File: jd239l05401; Date: 18-Jan-2007--"+" TRUE (2.9800km ,30.0m); "o" ESTIMATED (2.9800km ,29.9m); x=0.0100km, y= 0.8m

2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5

0

10

20

30

40

50

60

70 0.2

0.25

0.3

0.35

0.4

0.45

Range(km)

Dep

th(m

)

Maximum value of bartlett: 0.4988

File: jd239l05401; Date: 18-Jan-2007--"+" TRUE (2.9800km ,30.0m); "o" ESTIMATED (2.9800km ,29.2m); x=0.0100km, y= 0.8m

2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5

0

10

20

30

40

50

60

70 0.2

0.25

0.3

0.35

0.4

0.45

Range(km)

Dep

th(m

)

Maximum value of bartlett: 0.4898

File: jd239l09601; Date: 18-Jan-2007--"+" TRUE (4.9800km ,30.0m); "o" ESTIMATED (5.0500km ,32.8m); x=0.0100km, y= 0.8m

4.5 4.6 4.7 4.8 4.9 5 5.1 5.2 5.3 5.4 5.5

0

10

20

30

40

50

60

70

80

0.2

0.25

0.3

0.35

0.4

0.45

Range(km)

Dep

th(m

)

Maximum value of bartlett: 0.5194

File: jd239l09601; Date: 18-Jan-2007--"+" TRUE (4.9800km ,30.0m); "o" ESTIMATED (5.1500km ,29.6m); x=0.0100km, y= 0.8m

4.5 4.6 4.7 4.8 4.9 5 5.1 5.2 5.3 5.4 5.5

0

10

20

30

40

50

60

70

80

0.2

0.25

0.3

0.35

0.4

0.45

ONR SW06 Workshop, January, 30-31, 2007 San Diego, CA

Discussion:

75 80 85

WD: 78.4009(m)

20 40 60

H: 52.4378(m)

1400 1600 1800

cp1: 1611.5787(m/s)

2000 2500

cpb: 1988.2227(m/s)

0.5 1

p1: 0.5535(dB/m/kHz)

0.5 1

pb: 0.5103(dB/m/kHz)

1.5 2 2.5

1: 1.7968(g/cm 3)

2 2.5 3

b: 2.6831(g/cm 3)

25 30 35

SD: 30.6447(m)

0.5 1 1.5

Range: 1.0724(km)

8 10 12 14

rdvb: 12.2129(m)

1 1.5 2

fexp: 1.0645

0 5 10

tilt: 1.9609( )

0 100

Steer: 114.4619( )

File: wp21lm.dat; Date: 20-Jan-2007

Way Point 21(0.98km), LF(5mins) + MF(5mins) Tonal, 8 fres

ONR SW06 Workshop, January, 30-31, 2007 San Diego, CA

75 80 85

WD: 78.6614(m)

20 40 60

H: 52.2724(m)

1400 1600 1800

cp1: 1652.5365(m/s)

2000 2500

cpb: 1889.8889(m/s)

0 0.5 1

p1: 0.9960(dB/m/kHz)

0.5 1

pb: 0.0107(dB/m/kHz)

1.5 2 2.5

1: 1.8669(g/cm 3)

2 2.5 3

b: 2.9973(g/cm 3)

20 30 40

SD: 31.3392(m)

2.5 3 3.5

Range: 3.0363(km)

10 15

rdvb: 12.0089(m)

1 2 3

fexp: 2.1332

0 5 10

tilt: 1.6897( )

0 100

Steer: 78.7805( )

File: wp22.dat; Date: 20-Jan-2007

Way Point 22(2.98km), LF(5mins) Tonal(53, 103 203, 253)Hz

ONR SW06 Workshop, January, 30-31, 2007 San Diego, CA

Way Point 23(4.98km), LF(5mins) Tonal(53, 103 203, 253)Hz

75 80 85

WD: 80.6887(m)

20 40 60

H: 61.2443(m)

1400 1600 1800

cp1: 1627.5771(m/s)

2000 2500

cpb: 1995.1620(m/s)

0 0.5 1

p1: 0.9977(dB/m/kHz)

0.5 1

pb: 0.0126(dB/m/kHz)

1.5 2 2.5

1: 2.0976(g/cm 3)

2 2.5 3

b: 2.6372(g/cm 3)

20 30 40

SD: 30.5472(m)

4.5 5 5.5

Range: 5.2361(km)

10 15

rdvb: 9.4056(m)

1 2 3

fexp: 1.4695

0 5 10

tilt: 3.6891( )

0 100

Steer: 126.3276( )

File: wp23.dat; Date: 20-Jan-2007