Azimuthal dependent intensity fluctuations during Event-50 J. Luo, - - PowerPoint PPT Presentation

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Azimuthal dependent intensity fluctuations during Event-50 J. Luo, - - PowerPoint PPT Presentation

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Azimuthal dependent intensity fluctuations during Event-50 J. Luo, M. Badiey, and E. A. Karjadi J. Luo, M. Badiey, and E. A. Karjadi College of Marine and Earth Studies, University of College of Marine and Earth Studies, University of Delaware

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SLIDE 1

Azimuthal dependent intensity fluctuations during Event-50

  • J. Luo, M. Badiey, and E. A. Karjadi
  • J. Luo, M. Badiey, and E. A. Karjadi

College of Marine and Earth Studies, University of College of Marine and Earth Studies, University of Delaware Delaware

  • B. Katsnelson
  • B. Katsnelson

Voronezh University, Russia Voronezh University, Russia

  • J. F. Lynch
  • J. F. Lynch

Woods Hole Oceanographic Institution Woods Hole Oceanographic Institution

  • J. N. Moum
  • J. N. Moum

College of Oceanic & Atmospheric Sciences, Oregon College of Oceanic & Atmospheric Sciences, Oregon State University State University

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SLIDE 2

Acknowledgements Acknowledgements

We wish to thank the Office of Naval Research particularly Drs. Ellen Livingstone and Robert Headrick from 321 OA Program.

Research collaborators:

  • J. Lynch (Woods Hole Oceanographic Institution)
  • B. Katsnelson (Voronezh State University)
  • W. Seigmann (Rensselaer Polytech Inst.)
  • Harry DeFerrari (RSMAS, Univ. Miami)
  • D. Rouseff (APL, University of Washington)
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SLIDE 3

Objectives Objectives

Investigate 3D effects of internal wave (IW) on the broadband acoustic propagation:

  • Azimuthal dependency of the field due

Azimuthal dependency of the field due to IW propagation. to IW propagation.

  • Study different regimes of propagation:

Study different regimes of propagation: adiabatic, horizontal refraction, mode adiabatic, horizontal refraction, mode coupling, and the transitions between coupling, and the transitions between them them

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Background Background

  • Oceanographic observations of shallow water

Oceanographic observations of shallow water internal waves [Zhou internal waves [Zhou et al. et al. (1991), Rubenstein (1991), Rubenstein et al. et al. (1991), Rubenstein (1999)]. (1991), Rubenstein (1999)].

  • SWARM95 observation of acoustic effects

SWARM95 observation of acoustic effects [Badiey [Badiey et al. et al. ( 2002)]. ( 2002)].

  • Theoretical explanation and hypothesis

Theoretical explanation and hypothesis [Badiey [Badiey et al. et al. JASA 117(2), 2005 and JASA JASA 117(2), 2005 and JASA 122(2), 2007]. 122(2), 2007].

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SLIDE 5

Experiment Experiment Waveguide Waveguide Internal Internal solitons solitons Signal Signal Results Results

Zhou et al. (1991). JASA 90(4), 2042-2054 Yellow sea L= 28 km; D=40 m Hypothesized α > 45o Broadband 100-1000 Hz

  • Freq. fluct. > 20 dB

Resonant mode Coupling Rubenstein & Brill, Ocean Variability and Acoust., 215-228 (1991). Washington coast L=18.5km; D=150m N~10 cph Ampl ~ 10 m α ~ 10-15o Narrowband f = 400 Hz

  • Temp. intens. fluct. ~ 3 dB

Adiabatic fluctuations Rubenstein, D. (1999) IEEE J. Oceanic Eng. 24(3), 346-357. Gulf of Mexico L= 30km; D=185m N ~ 15–20 cph Ampl ~ 10 m α ~ 30o Narrowband f = 240 Hz

  • Temp. intens. fluct. ~ 2 dB

Mode coupling Badiey, Lynch, et al. (2002). IEEE J. Oc.Eng., v.27, N1, 117-129. New Jersey shelf L=15 km; D=70 m N ~ 10-15 cph Ampl ~ 12 m α ~ 5o Broadband 30-160 Hz and LFM 50-250 Hz Space-time int. fluct.~ 6-7dB 3D effects (horizontal refraction) Badiey, Lynch, et al. (2002). IEEE J. Oc.Eng., v.27, N1, 117-129. New Jersey shelf L=19 km; D=70-100m N ~ 10-15 cph Ampl ~ 12 m α ~ 35-40o Broadband 30-160 Hz and LFM 50-250 Hz Space-time int. fluct.~2-3 dB Mode coupling Badiey, Katsnelson, Lynch, et al. JASA 2005 - 117(2), 613-625. 2007 - 122(2), 747-760. New Jersey shelf L=15 km; D=70 m N ~ 10-15 cph Ampl ~ 12 m α ~ 5o Broadband 30-160 Hz Space-time int. fluct.~ 6-7dB 3D effects Frequency dependence Luo, Badiey, Katsnelson, Lynch, et al. JASA EL 2008 - 124(3) New Jersey shelf L=20 km; D=70 m N ~ 10-15 cph Ampl ~ 12 m α ~ 3o - 5o Broadband 270-330 Hz Space-time int. fluct.~15dB 3D effects Frequency dependence

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SLIDE 6

Shark VHLA Shark VHLA

Vertical linear array (VLA)

16 hydrophones 3.5 m spacing 64 m of vertical aperture

  • Horizontal linear array (HLA)

32 hydrophones 15 m spacing 478 m of horizontal aperture

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SLIDE 7

Previous study Previous study

 Before & During IW event

Before & During IW event

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IW reconstruction IW reconstruction

 Radar image

Radar image

 Interpolation using

Interpolation using thermistor farm record thermistor farm record

R/V Sharp radar R/V Oceanous radar Thermistor farm R/V Sharp radar R/V Oceanous radar Thermistor farm

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Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Shark array

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Received Signal on VLA Received Signal on VLA 21:11 -21:29 (no IW)

21:11 -21:29 (no IW)

Depth = 69.75 m Depth = 47.25 m Depth = 39.75 m Depth = 28.50 m

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SLIDE 11

Depth = 69.75 m Depth = 47.25 m Depth = 39.75 m Depth = 28.50 m

21:41 -21:59 (angle <5 21:41 -21:59 (angle <5o

  • )

)

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SLIDE 12

Depth = 69.75 m Depth = 47.25 m Depth = 39.75 m Depth = 28.50 m

22:41 -22:59 (angle = 15 22:41 -22:59 (angle = 15o

  • - 27
  • 27o
  • )

)

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Acoustic wave propagation mechanisms governed by the direction

  • f acoustic track relative to the internal wave front.

Preliminary analysis of acoustic data Preliminary analysis of acoustic data

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Angular distribution of acoustic Angular distribution of acoustic intensity intensity

Zone 1 Zone 2 Zone 3 Zone 4 Zone 5

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SLIDE 15

Zone 1 Zone 2 Zone 3

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SLIDE 16

Zone 4 Zone 5

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SLIDE 17

track, m antenna, m time-0min-frequency-100-Hz-mode-1 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

  • 1000
  • 800
  • 600
  • 400
  • 200

200 400 600 800 1000

  • 2.2
  • 2
  • 1.8
  • 1.6
  • 1.4
  • 1.2
  • 1
  • 0.8
  • 0.6
  • 0.4
  • 0.2

track, m antenna, m time-2min-frequency-100-Hz-mode-1 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

  • 1000
  • 800
  • 600
  • 400
  • 200

200 400 600 800 1000

  • 1.2
  • 1
  • 0.8
  • 0.6
  • 0.4
  • 0.2

track, m antenna, m time-0min-frequency-100-Hz-mode-2 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

  • 1000
  • 800
  • 600
  • 400
  • 200

200 400 600 800 1000

  • 1.6
  • 1.4
  • 1.2
  • 1
  • 0.8
  • 0.6
  • 0.4

track, m antenna, m time-2min-frequency-100-Hz-mode-2 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

  • 1000
  • 800
  • 600
  • 400
  • 200

200 400 600 800 1000

  • 1.4769
  • 0.8384
  • 0.2
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SLIDE 18

Summary Summary

 New data set is analyzed from a moving

New data set is analyzed from a moving source to chase the IW for depicting source to chase the IW for depicting refraction refraction

 Appearance of the unexpected intensity

Appearance of the unexpected intensity fluctuation can be related to the fluctuation can be related to the redistribution of sound field in the redistribution of sound field in the horizontal plane horizontal plane

 The redistribution is very sensitive to the

The redistribution is very sensitive to the position of the source with respect to IW position of the source with respect to IW and the shape of IW front and the shape of IW front