Outline

• Glider acoustics

• Combustive sound source inversions

• 3D effects of front and internal waves

• Papers in progress

Preliminary Results

James H. Miller and Gopu R. Potty

ARLThe University of Texas at Austin

Hydrophone Mounted on Slocum Glider

• Results– Initial test worked well ~1/2 hour of data– Full test glider flew 200km over 14 days!– Undocumented software feature in Bioprobe

caused early termination– Another test planned for this winter

Towed configuration

Single Phone Data from Glider

400 Hz WHOI tomo source

224 Hz WHOI tomo source

200 Hz Miami source

300 Hz NRL FM chirps

Glider ‘Clicks’

Glider whine

Collaborators: Jason Holmes, Jim Lynch,Scott Glenn, Josh Kohut, Hugh Roarty

Glider Location

Acoustic glider location

Measured Phase Stability

Phase of 224 Hz source stable and linear over timeGlider click

Miami soundmachine

224 Hz WHOI source

Glider clickMiami soundmachine on

Synthetic Aperture Output

• 224 Hz tomography signal carrier

• Beamformer turned on at 50 seconds

Glider click

Synthetic Aperture Beamformer

224 Hz carrier

MSM 200 Hz tomo sideband?

Pulse compressed

MSM Interference

Glider click

Mode 1Mode 2

Combustive Sound Source (CSS) Data on the SHRUs

Shru 1; 15.27 km

•Source deployed from R/V Knorr by Preston Wilson/ David Knobles•Source waveform monitored•Source depth ~ 26 m•Inversions using CSS data (using mode travel times)•Collaborators: Lynch, Newhall, Wilson, Knobles, Hodgkiss, Chapman

Mode 1

Mode 2

ARLThe University of Texas at Austin

Frontal Reflection Effects on CW TL

10o C

15o C

Source Receiver

Range

1 km

Front

0 5 10 15 20 25 30 35 40

-15

-10

-5

0

5

10

15

range (km)

tran

smis

sio

n lo

ss d

iffe

ren

ce a

t re

ceiv

er

Effect of a Nearby Front on Propagation (dB)

Fixed frequency= 200 HzVarying range

Lynch, J.F.; Colosi, J.A.; Gawarkiewicz, G.; Duda, T.F.; Pierce, A.D.; Badiey, M.; Katsnelson, B.G.; Miller, J.H.; Siegmann, W.; Chiu, C.-S.; Newhall, A.,“Consideration of Fine-Scale Coastal Oceanography and 3-D Acoustics Effects for the ESME Sound Exposure Model,” IEEE J. Ocean. Eng., 31, (1), 33 – 48, (2006).

28.2 km

30.3 km

34.7 km

Frequency – 93 HzSource depth ~ 50 mSource Level – 165 – 168 dBCollaborators: Lynch, Newhall, Badiey, Duda, Gawarkiewicz

J-15 Tow Parallel to the Shelf Break Front

This image 16 hours later than transect, Internal wave seen on ship’s radar inshore of Knorr at 11 PM Local (0400 GMT 9/5/06)

Shark

Knorr 3D J-15 Run Track

J-15 Tow Parallel to the Front: Model

Front

Internal wave packet

WHOI HLA/VLA(Shark)

Frequency – 93 HzSource depth ~ 50 mSource Level – 165 – 168 dBCollaborators: Lynch, Newhall

2 modes

Ship track

28.2 km

34.7 km

Frequency – 93 HzSource depth ~ 50 mSource Level – 165 – 168 dBCollaborators: Lynch, Newhall

J-15 Tow Parallel to the Front: Data

J-15 on

Fron

t

Inte

rnal

wave

pack

et

Knorr track

Range km 25 30 35 40 45 50

Data shows 20 dB increase, model only 10 dB.Where is the other 10 dB coming from?Curvature of front? Internal wave structure?

ASA Meeting - Abstracts

1. The effect of a rough sea surface on acoustic normal modes (Miller and Lynch -Medwin session, invited)

2. Observations of phase and travel time variations of normal modes during Tropical Storms Ernesto and Florence (Langer, Miller, Potty, Lynch, Newhall)

3. Geoacoustic inversion using combustive sound source signals (Potty, Miller, Wilson, Lynch, Newhall)

4. Acoustic measurements in shallow water using an ocean glider (Georges A. Dossot, James H. Miller, Gopu R. Potty, Kristy A. Moore, Jason D. Holmes, ScottGlenn, and Jim Lynch)

5. Investigation of 3D propagation effects at the New Jersey shelf break front (Kristy A. Moore, James H. Miller, Gopu R. Potty, Georges Dossot, James Lynch, Arthur Newhall, and Glen Gawarkiewicz)

ARLThe University of Texas at Austin