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Broadband matched-field sourceBroadband matched-field sourcelocalization in the East China Sea*localization in the East China Sea*

RenheRenhe Zhang Zhang ZhenglinZhenglin Li LiJin Jin Yan ZhaohuiYan Zhaohui Peng FenghuaPeng Fenghua Li Li

National Laboratory of Acoustics, Institute of Acoustics,National Laboratory of Acoustics, Institute of Acoustics,Chinese Academy of Sciences, Beijing, ChinaChinese Academy of Sciences, Beijing, China

** The work was supported by the National Natural The work was supported by the National NaturalScience Foundation of China and ONRScience Foundation of China and ONR

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OutlineOutline

nn IntroductionIntroductionnn Experiment descriptionExperiment descriptionnn Environment of oceanEnvironment of oceannn Matched field processingMatched field processingnn Sound propagation modelSound propagation modelnn MFP source localization resultsMFP source localization resultsnn ConclusionConclusion

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IntroductionIntroduction

nn ASIAEx2001was performed in the EastASIAEx2001was performed in the EastChina Sea.China Sea.

nn The environment is some complicatedThe environment is some complicated

nn The effects of water depth mismatch onThe effects of water depth mismatch onMFP source localization are investigatedMFP source localization are investigatedexperimentally.experimentally.

nn The effects of simplified The effects of simplified SVPsSVPs on MFP on MFPsource localization are investigated also.source localization are investigated also.

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Experiment descriptionExperiment description

Shiyan2

32-elements VLA

Shiyan3

38g WBS(50m)

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The actual WBS drop locationsThe actual WBS drop locations

O: the site of Shiyan3

Direction O-E: Fromcenter(O) to Southwest (E)

Direction F-O-G-J : FromNorthwest to Southeast

Given by Jim MillerGiven by Jim Miller

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The Ocean EnvironmentThe Ocean Environment

nn Experiment site is a continental slopeExperiment site is a continental slopeenvironment. the sea depth vary from 96menvironment. the sea depth vary from 96mto 150m in 80km range.to 150m in 80km range.

nn The temperature of sea water has some The temperature of sea water has somefluctuation from sea surface to 70m depth.fluctuation from sea surface to 70m depth.

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SVP of sea water used in MFPSVP of sea water used in MFPsource localizationsource localization

From 2001/06/03/20:50 to 2001/06/03/23:50

1518 1520 1522 1524 1526 1528 1530

0

20

40

60

80

100

Sound speed (m/s)

Dep

th (

m)

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Sea-water depth from center(O)Sea-water depth from center(O)to southwest (E)to southwest (E)

0 5 10 15 20 25 30

95

100

105

110

115

Sea depth of direction O-E

Range(km)

Dep

th(m

) O(29D40'N, 126D49'E)

E(29D26'N, 126D41'E)

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Sea-water depth from northwestSea-water depth from northwest(Site F) to southeast (Site J)(Site F) to southeast (Site J)

-30 -20 -10 0 10 20 30 40 50

80

90

100

110

120

130

140

150

Sea depth of direction F-O-G-J

Range(km)

Dep

th(m

)

F(29D48'N, 126D33'E)

O(29D40'N, 126D49'E)

J(29D29'N, 127D17'E)

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Matched field processorMatched field processor

=

∑∑

∑

==

=

N

i jci

N

i jei

N

i jijei

jMF

fpfp

fpfpfzrB

1

2

1

2

1c*

)()(

)()(),,(

∑ == fM

j jMFf

MF fzrBM

zrB1

),,(1

),(

2 Broadband MFP

1 Single frequency linear Bartlett MFP

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Sound propagation modelSound propagation modelnn The coupling normal mode-parabolic equationThe coupling normal mode-parabolic equation

theory based on the WKBZ approximationtheory based on the WKBZ approximation

[ ]∑∞

=

−−=

1

21

21

),;(),(),(),,(n

nnnc frzfrufrkrfzrp φ

uiKuAru

r

rvr

+−=∂∂

is the eigenvalue at local range rnk

nu is the normal mode coefficient, and satisfies

),,( frznφ is the eigenfunctionSolved by WKBZ

solved by split step PE method

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The geo-acoustic parameters ofThe geo-acoustic parameters ofsea bottomsea bottom

nn Sound speed Sound speed 1610.8m/s1610.8m/snn Density Density 1.86g/cm1.86g/cm33

nn Attenuation Attenuation 0.1dB/wavelength0.1dB/wavelength

nn Replica fields calculation parameters• Range step: 100m• Depth step: 2m• Frequency band : 100Hz - 200Hz.

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The range-depth ambiguousThe range-depth ambiguousfunction of a WBS at range 7.0kmfunction of a WBS at range 7.0km

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The range-depth ambiguousThe range-depth ambiguousfunction of a WBS at range 18.9 kmfunction of a WBS at range 18.9 km

MFP range 18.5km and depth 46m

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MFP results from center(Site O) toMFP results from center(Site O) tosouthwest(Site E) with a flat bottomsouthwest(Site E) with a flat bottom

0 5 10 15 20 25 30

0

20

40

60

80

100

GPS Range / km

MFP

Dep

th /

km

Direction O-E

MFP range results MFP depth results

0 5 10 15 20 25 300

5

10

15

20

25

30

GPS Range/km

MF

P R

ange

/km

Direction O-E

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MFP range results fromMFP range results fromnorthwest(F) to southeast(J)northwest(F) to southeast(J)

-30 -20 -10 0 10 20 30 40 50-30

-20

-10

0

10

20

30

40

50

GPS Range / km

MF

P R

ange

/ k

m

Direction F-O-G-J

Shiyan3

S ite F

S ite G

Site J

-30 -20 -10 0 10 20 30 40 50-30

-20

-10

0

10

20

30

40

50

GPS Range/km

MF

P R

ange

/km

Direction F-O-G-J

Flat bottom

Shiyan3

Slope bottom model Flat bottom model

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MFP depth results from northwestMFP depth results from northwest(Site F) to southeast(Site J)(Site F) to southeast(Site J)

Slope bottom model Flat bottom model

-30 -20 -10 0 10 20 30 40 50

0

10

20

30

40

50

60

70

80

90

100

GPS Range / km

MFP

Dep

th /

m

Direction F-O-G-J

Slope bottom

-30 -20 -10 0 10 20 30 40 50

0

10

20

30

40

50

60

70

80

90

100

GPS Range / kmM

FP D

epth

/ m

Direction F-O-G-J

Flat bottom

Shiyan3

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Simplification of the mean soundSimplification of the mean soundspeed profilespeed profile

1518 1520 1522 1524 1526 1528 1530

0

20

40

60

80

100

120

1

2 34

Speed (m/s)

Dep

th (

m)

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MFP range results MFP range results from Site O tofrom Site O to

Site J Site J with the simplified profileswith the simplified profiles

0 10 20 30 40 500

10

20

30

40

50

GPS Range (km)

MF

P R

ange

(km

)

0 10 20 30 40 500

10

20

30

40

50

GPS Range (km)

MF

P R

ange

(km

)

0 10 20 30 40 500

10

20

30

40

50

GPS Range (km)

MF

P R

ange

(km

)

0 10 20 30 40 500

10

20

30

40

50

GPS Range (km)

MF

P R

ange

(km

)

SVP1

SVP3 SVP4

SVP2

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SummariesSummaries

nn Broadband matched-field source localization isBroadband matched-field source localization isapplied to the VLA signals received in theapplied to the VLA signals received in thejointed ASIAEX 2001jointed ASIAEX 2001

nn For the slope bottom ocean environment, if weFor the slope bottom ocean environment, if wecalculate the replica fields using the flat bottomcalculate the replica fields using the flat bottommodel, significant errors can be introduced intomodel, significant errors can be introduced intothe range and depth localization predictions. Ifthe range and depth localization predictions. Ifthe depth mismatch is too large, it can notthe depth mismatch is too large, it can notlocalize the source properly.localize the source properly.

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SummariesSummaries

nn The accuracy of the source localization is largelyThe accuracy of the source localization is largelyimproved with the consideration of the slope ofimproved with the consideration of the slope ofthe bottom. The range estimates of the mostthe bottom. The range estimates of the mostsignals by MFP in the range from -30.0km tosignals by MFP in the range from -30.0km to50.0km are consistent with the GPS measured50.0km are consistent with the GPS measuredones well.ones well.

nn The effects of water sound speed profile on theThe effects of water sound speed profile on thematched field source localization are also studiedmatched field source localization are also studiedin the paper. For the four types of simplifications,in the paper. For the four types of simplifications,MFP processor could still give stable andMFP processor could still give stable andreliable estimation of source location.reliable estimation of source location.

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Thanks !Thanks !