INternal TIde Measurements with Acoustic Tomography Experiments
[PRAXIS XXI contract 2/2.1/MAR/1698/95]
Sérgio M. Jesussjesus@ualg.pt
UCEH - Universidade do Algarve,
Campus de Gambelas,
PT-8000 Faro, Portugal
CMO - Service Hidrographique Oceanographique de la Marine,
Emanuel F. Coelho
Rua das Trinas 49,
PT-1296 Lisboa, Portugal
Michael B. Porter email@example.com
Centre of Applied Mathematics,
New Jersey Institute of Technology,
NJ Newark, USA
Today acoustics is one of the main tools for ocean exploration.
Inspired by a technique from biomedical engineering, Ocean Acoustical
Tomography (OAT) consists of the use of one or more acoustic
sensors/sources strategically distributed in a volume of water and
simultaneously emitting and receiving coded signals. The ``comparison''
of the emitted and
received signals allows for the acoustical characterization of the
environment in between the source(s) and the receiver(s). The
experiments that have been performed to date, mainly in deep water,
showed that it is possible to estimate: (1) the temperature over the
water column, (2) the physical characteristics of the seabottom and (3)
the velocity and direction of currents.
Due to the large water mass involved and its periodic nature,
internal tides signatures have been frequently observed during ocean
tomography experiments in the Bay of Biscay. In the continental shelf,
internal tides are extremely important to the study of the coastal
dynamics with a very special relevance close to the shelf break and to
topographic irregularities like submarine canyons. This project aims at
proving the concept of using vertical arrays of sensors and acoustic
sources in the band 50 - 400 Hz for tomographic estimation of the
oceanographic characteristics of internal tides on the continental
up to 200 m depth. During the project, areas of interest near the
coast will be selected for at sea testing including the validation of
the tomographic results with ground truth measurements. The conclusions
of this study are hoped to bring a better knowledge of the internal
tide phenomena and its
impact on the coast dynamics. This should lead to improved prediction
accuracy for coastal dynamical models and to a better management of
existing resources. The results will also be important
in providing more refined predictions of the impact of potential
ecological accidents and climate changes.
- To conduct a theoretical/parametric study for determining the
performance of a source-receiver system for the inversion of
oceanographic parameters in shallow water. Determine the
characteristics of the system (frequency, resolution, array aperture,
depth, etc.,...) for an optimal performance on typical scenarios off
the portuguese/french coast using oceanographic archival data.
- To establish the capabilities of the tomographic system to
study internal tides on the continental shelf. Test of
theoretical-parametric models and estimation of their characteristic
- To test the complete system in preselected coastal areas and
validate it with ground truth data.
- To draw conclusions on the limitations of the theoretical and
operational methods that were developed. Make recommendations for
future developements of OAT systems in shallow water and their use for
studying internal tides.
Plan of activities
During INTIMATE the following important milestones are forseen:
- a first small scale sea trial for testing the feasibility of the
project, along the portuguese coast, nearby Lisbon.
- from the conclusions of the first sea trial, both from the
sea trial design and the data analysis, a second full scale sea trial
his planned in conjunction with the MINT (CMO-SHOM) experiment along
the French coast nearby Brest.
- a third sea trial in another location to be chosen based on
the experience of the first two experiments.
INTIMATE'96 sea trial
The first small scale sea trial, INTIMATE'96, took place
near the Nazaré site from 14 to 19 of June 1996.
Two research vessels were involved: the NRP ANDROMEDA and the BO
D'ENTRECASTEAUX. BO D'ENTRECASTEAUX was towing a sound source
and emmiting coded signals along pre-determined geometries. NRP
ANDROMEDA was lying dead in the water nearby a 4 hydrophone vertical
array receiving radio signals and recording the data. The receiving
vertical array was loaned by courtesy of SACLANT Undersea Research
La Spezia, Italy.
Ground truth measurements
A number of environmental measurements were performed simultaneously
the acoustic data transmissions:
- bathymetry surveys of the area and along transmission lines
- bottom moored ADCP data at the vertical array location
- thermistor chains at the vertical array location
- CTD data at the vertical array location
- hull mounted ADCP on the source ship
- XBT data from the source ship
- CTD data over night and along the area
- seismic survey with Uniboom
- cores along source tracks
Data analysis (see Ocean
Acoustic Library for more results on line)
Superficial analysis of the CTD data at the vertical array location
shows evidence of a approximately 12 hour period movement of the
thermocline with an amplitude of about 10 m/s extending from 10 to 30 m
Cross-correlograms of the received and emitted signals shows a very
channel impulse response both for the flat bottom and range dependent
Source localization using single hydrophone data and the full source
frequency band has been possible for both the stationnary and the
moving source events.
INTIMATE'98 sea trial
INTIMATE'98 toke place during July 1998 in the shallow water zone at
the border of the continental platform SW from Brest, France. Two
sources and two receiving arrays were employed along a number of
transects for tomographic reconstruction. Three research vessels were
involved: the ALCYON, the LAPEROUSE and the HMS ROEBUCK.
INTIMATE'99 sea trial
INTIMATE'99 toke place from 19 to 23 July 1999 in the Troia
Peninsula, near Setubal, Portugal (see
INTIFANTE'99 Sea Trial )
INTIFANTE'00 sea trial
INTIFANTE'00 is taking place from 9 to 29 October 2000 in the
Tróia Peninsula, near Setubal, Portugal (see INTIFANTE'00 Sea Trial )
Publications and reports
- JESUS S.M. and PORTER M.B., ``Shallow water tomography for
internal tide estimation: preliminary results of INTIMATE'96.'',
SACLANTCEN SCNR Meeting, Lisbon, October 1996.
- COELHO E., JESUS S., PORTER M. and STEPHAN Y., ``Preliminary
acoustic results from the INTIMATE 96 shallow water tomography
experiment'', ONR/ARPA Shallow-water Acoustic Workshop, Washington DC,
- JESUS S.M. e PORTER M.B., ``Shallow water tomography for internal
tide estimation: preliminary results of INTIMATE'96.'', SACLANTCEN SCNR
Meeting, Lisboa, 1996.
- STEPHAN Y, DEMOULIN X., JESUS S., COELHO E.F. and PORTER M.B.,
``Internal tide impact measured by acoustic tomography experiment
(INTIMATE)'', 132 Meeting of the Acoust. Soc. Am., Hawai, December
- COELHO E., JESUS S., PORTER M. and STEPHAN Y., ``One-way active
tracking in the INTIMATE 96 Experiment'', EAST Symposium, Washington
DC, February 1997.
- PORTER M.B., JESUS S., STEPHAN Y., DEMOULIN X. and COELHO E.,
``Exploting reliable features of the ocean channel response'', Proc. of
SWAC'97, Beijing, April 1997.
- DEMOULIN X., STEPHAN Y., JESUS S., COELHO E. and PORTER M.B.,
``INTIMATE96: a shallow water tomography experiment devoted to the
study of internal tides'', Proc. of SWAC'97, Beijing, April 1997.
- PORTER M.B., STEPHAN Y., DEMOULIN X., JESUS S. and COELHO E.,
``Shallow-water tracking in the sea of Nazaré'' Undersea
IEEE Ocean Engineering Society, Tokyo, Japan, 1998.
- JESUS S.M., PORTER M.B, STEPHAN Y., COELHO E. and DEMOULIN X,
``Broadband source localization with a single hydrophone'', Proc.
OCEANS'98, pp. 1078-1082, Nice, France, 1998.(abstract).
- RODRIGUEZ O.C., JESUS S., STEPHAN Y., PORTER M., COELHO E.,
acoustic tomography: reliability of the normal modes expansion as a
basis for solving the inverse problem'', 4th European Conf. on
Underwater Acoustics, pp. 587-592, Rome, Italy, September 1998 (abstract).
- PORTER M.B., JESUS S.M., STEPHAN Y., COELHO E., DEMOULIN X.,
``Single-phone source tracking in a variable environment'', 4th
European Conf. on Underwater Acoustics, pp. 575-580, Rome, Italy,
- JESUS S. M., PORTER M.B., STEPHAN Y., DEMOULIN X., RODRIGUEZ O.
and COELHO E., ``Single hydrophone source localization'', (abstract), IEEE Journal of Oceanic
(pdf file), Vol.25, no.3, pp.-337-346 1998.
- PORTER M.B.,STEPHAN Y., DEMOULIN X., JESUS S. and COELHO E.,
``Shallow-water tracking in the sea of Nazaré'', submitted to
IEEE Journal of Oceanic Eng., October 1998.
- PORTER M.B., JESUS S., STEPHAN Y., DEMOULIN X., COELHO E.,
echo pattern to range a sound source'', Proc. of First International
Symposium on Physics in Signal and Image Processing, Paris, January 1999.
- O.C. RODRÍGUEZ, S.M. JESUS, Y. STEPHAN, X. DEMOULIN, M.B.
and E. COELHO, ``Nonlinear soliton interaction with acoustic signals:
effects'', Int. Conf. on Theoretical and Computational Acoustics,
Trieste, Italy 1999.
- JESUS S.M., ``Internal Tide Measurements with Acoustic Tomography
Experiments (INTIMATE)'', SACLANTCEN SCNR Meeting, La Spezia, Italy,
- RODRIGUEZ O.C., JESUS S.M., PORTER M.B., STEPHAN Y., DEMOULIN X
e COELHO E., ``Dynamics of acoustic propagation through a soliton wave
packet: observations from the INTIMATE'96 experiment'', in
Experimental Acoustics Inversion Methods for Exploration of the Shallow
Water Environment, Ed.Caiti, Hermand, Jesus and Porter, KLUWER,
- Y.STEPHAN, T. FOLEGOT, X. DEMOULIN, M.PORTER, S. JESUS e
E. COELHO, ''The interaction of Sound and Tides'', in Experimental
Acoustics Inversion Methods for Exploration of the Shallow Water
Environment, Ed.Caiti, Hermand, Jesus and Porter, KLUWER, 1999.
- M.B. PORTER, S.M. JESUS, Y. STEPHAN, X. DEMOULIN e
E.COELHO, ``Tidal effects on source inversion'', in Experimental
Acoustics Inversion Methods for Exploration of the Shallow Water
Environment , Ed.Caiti, Hermand, Jesus and Porter, KLUWER, 1999.
- RODRIGUEZ O.C., JESUS S., STEPHAN Y., DEMOULIN X., PORTER M. and
COELHO E., ``Nonlinear Soliton Interaction with Acoustic Signals:
Focusing effects'', (abstract), Journal
of Computational Acoustics,
(gziped ps file), accepted 2000.
- RODRIGUEZ O.C. e JESUS S.M.,``Physical limitations of travel time
based shallow water tomography''(abstract),
Journal of the Acoustical Society of America, (pdf file),
- DEMOULIN X., STEPHAN Y., COELHO E., FOLEGOT T., JESUS S.M., and
PORTER M.B., ''Estimating equivalent bottom geoacoustical parameters
from broadband inversion'', 5th European Conference on Underwater
Acoustics, pp. 191-196, Lyon, France, 2000.
- JESUS S.M., PORTER M.B., STEPHAN Y., COELHO E., RODRIGUEZ O.C.
and DEMOULIN X., ''Single sensor source localization in a range
environment'', (abstract) MTS/IEEE
Oceans 2000, Providence, USA, 2000.
- RODRIGUEZ O.C. and JESUS S.M., "Range-dependent regularization of
travel-time tomography based on theoretical modes'', (pdf)
accepted ECUA'02, June.
- MARTINS N.E. and JESUS S.M., ``Blind Channel Estimation with Data
the INTIMATE'96 sea trial'', (pdf)
accepted MED'2002, June.
- TOLSTOY A., JESUS S.M. and RODRIGUEZ O., "Tidal effects on MFP
the INTIMATE'96 test",
accepted Acoustic Variability Conf., Lerici, Italy, September.
- TOLSTOY A., JESUS S. and RODRIGUEZ O., "Tidal MFP inversion for
water depth and source range in the Intimate96 Test", (abstract)
submitted to the ASA Meeting, December 2002.
last update on Jun 21, 2002