Acoustical oceanography

Short description: Use of underwater sound to study the sea, its boundaries and its contents

Acoustical oceanography is the use of underwater sound to study the sea, its boundaries and its contents.

A 38 kHz hydroacoustic tow fin used to conduct acoustic surveys by NOAA. Alaska, Southeast.

## Contents

* 1 History
* 2 Equipment used
* 3 Theory
* 4 Measurements
* 5 Applications
* 5.1 Depth sounding
* 5.2 Marine biology
* 6 See also
* 7 References
* 8 External links

## History

Interest in developing echo ranging systems began in earnest following the sinking of the RMS Titanic in 1912. By sending a sound wave ahead of a ship, the theory went, a return echo bouncing off the submerged portion of an iceberg should give early warning of collisions. By directing the same type of beam downwards, the depth to the bottom of the ocean could be calculated.[1]

The first practical deep-ocean echo sounder was invented by Harvey C. Hayes, a U.S. Navy physicist. For the first time, it was possible to create a quasi-continuous profile of the ocean floor along the course of a ship. The first such profile was made by Hayes on board the U.S.S. Stewart, a Navy destroyer that sailed from Newport to Gibraltar between June 22 and 29, 1922. During that week, 900 deep-ocean soundings were made.[2]

Using a refined echo sounder, the German survey ship Meteor made several passes across the South Atlantic from the equator to Antarctica between 1925 and 1927, taking soundings every 5 to 20 miles. Their work created the first detailed map of the Mid-Atlantic Ridge. It showed that the Ridge was a rugged mountain range, and not the smooth plateau that some scientists had envisioned. Since that time, both naval and research vessels have operated echo sounders almost continuously while at sea.[3]

Important contributions to acoustical oceanography have been made by:

* Leonid Brekhovskikh
* Walter Munk
* Herman Medwin
* John L. Spiesberger
* C.C. Leroy
* David E. Weston
* D. Van Holliday
* Charles Greenlaw

## Equipment used

The earliest and most widespread use of sound and sonar technology to study the properties of the sea is the use of a rainbow echo sounder to measure water depth. Sounders were the devices used that mapped the many miles of the Santa Barbara Harbor ocean floor until 1993.

Fathometers measure the depth of the waters. It works by electronically sending sounds from ships, therefore also receiving the sound waves that bounces back from the bottom of the ocean. A paper chart moves through the fathometer and is calibrated to record the depth.

As technology advances, the development of high resolution sonars in the second half of the 20th century made it possible to not just detect underwater objects but to classify them and even image them. Electronic sensors are now attached to ROVs since nowadays, ships or robot submarines have Remotely Operated Vehicles (ROVs). There are cameras attached to these devices giving out accurate images. The oceanographers are able to get a clear and precise quality of pictures. The 'pictures' can also be sent from sonars by having sound reflected off ocean surroundings. Oftentimes sound waves reflect off animals, giving information which can be documented into deeper animal behaviour studies.[4][5][6]

## Theory

See Clay and Medwin.[7]

## Measurements

See Clay and Medwin.[7]

## Applications

Applications of acoustical oceanography include:

* fish population surveys
* classification of fish species and other biota
* rain rate measurement
* wind speed measurement
* water depth measurement
* seabed classification
* ocean acoustic tomography
* global thermometry
* monitoring of ocean-atmospheric gas exchange

### Depth sounding

### Marine biology

Main article: Physics:Bioacoustics

The study of marine life, from microplankton to the blue whale, uses bioacoustics.[8]

## See also

* Ocean exploration
* Cambridge Interferometer

## References

1. ↑ Garrison, Tom. Essentials of Oceanography. 6th ed. Pacific Grove, CA: Brooks Cole, 2012. p.79.
2. ↑ Kunzig, Robert. Mapping the Deep: The Extraordinary Story of Ocean Science. New York: Norton 2000. p. 40-41.
3. ↑ Stewart, Robert. Introduction to Physical Oceanography, University Press of Florida, 2009 p. 28.
4. ↑ "Oceanography". Scholastic Teachers. http://www.scholastic.com/teachers/article/oceanography.
5. ↑ "Tools of the Oceanographer". marinebio.net. http://www.marinebio.net/marinescience/01intro/tomeas.htm.
6. ↑ "Technology used". noc.ac.uk. http://noc.ac.uk/science-technology/life-oceans/technology-used.
7. ↑ 7.0 7.1 C. S. Clay & H. Medwin, Fundamentals of Acoustical Oceanography (Academic, Boston, 1998).
8. ↑ E. J. Simmonds & D. N. MacLennan, Fisheries Acoustics, Second Edition (Blackwell, Oxford, 2005).

## External links

* ASA Acoustical Oceanography Technical Committee

* v
* t
* e

Hydroacoustics

Sonar|

* Active acoustics
* Baffles (submarine)
* Bistatic sonar
* Echo sounding
* Fessenden oscillator
* GLORIA sidescan sonar
* Multibeam echosounder
* Passive acoustics
* Scientific echosounder
* Side-scan sonar
* Sonar beamforming
* Sonobuoy
* Surveillance Towed Array Sensor System
* Synthetic aperture sonar
* Towed array sonar
* Upward looking sonar

Ocean acoustics|

* Acoustic network
* Acoustic release
* Acoustic Doppler current profiler
* Acoustic seabed classification
* Acoustical oceanography
* Hydrophone
* Long baseline acoustic positioning system
* Ocean acoustic tomography
* Short baseline acoustic positioning system
* Sofar bomb
* SOFAR channel
* Sound speed gradient
* Sound velocity probe
* Ultra-short baseline
* Underwater acoustics
* Underwater acoustic communication
* Underwater acoustic positioning system

Acoustic ecology|

* Acoustic survey in fishing
* Acoustic tag
* Animal echolocation
* Beached whale
* Deep scattering layer
* Fishfinder
* Fisheries acoustics
* Hearing range of marine mammals
* Marine mammals and sonar
* Whale song

Related topics|

* Acoustic signature
* Bioacoustics
* Biophony
* Geophysical MASINT
* Hydrographic survey
* Noise map
* Soundscape

* v
* t
* e

Physical oceanography

Waves|

* Airy wave theory
* Ballantine scale
* Benjamin–Feir instability
* Boussinesq approximation
* Breaking wave
* Clapotis
* Cnoidal wave
* Cross sea
* Dispersion
* Edge wave
* Equatorial waves
* Fetch
* Gravity wave
* Green's law
* Infragravity wave
* Internal wave
* Iribarren number
* Kelvin wave
* Kinematic wave
* Longshore drift
* Luke's variational principle
* Mild-slope equation
* Radiation stress
* Rogue wave
* Rossby wave
* Rossby-gravity waves
* Sea state
* Seiche
* Significant wave height
* Soliton
* Stokes boundary layer
* Stokes drift
* Stokes wave
* Swell
* Trochoidal wave
* Tsunami
* megatsunami
* Undertow
* Ursell number
* Wave action
* Wave base
* Wave height
* Wave power
* Wave radar
* Wave setup
* Wave shoaling
* Wave turbulence
* Wave–current interaction
* Waves and shallow water
* one-dimensional Saint-Venant equations
* shallow water equations
* Wind wave
* model

Circulation|

* Atmospheric circulation
* Baroclinity
* Boundary current
* Coriolis force
* Coriolis–Stokes force
* Craik–Leibovich vortex force
* Downwelling
* Eddy
* Ekman layer
* Ekman spiral
* Ekman transport
* El Niño–Southern Oscillation
* General circulation model
* Geochemical Ocean Sections Study
* Geostrophic current
* Global Ocean Data Analysis Project
* Gulf Stream
* Halothermal circulation
* Humboldt Current
* Hydrothermal circulation
* Langmuir circulation
* Longshore drift
* Loop Current
* Modular Ocean Model
* Ocean dynamics
* Ocean gyre
* Princeton ocean model
* Rip current
* Subsurface currents
* Sverdrup balance
* Thermohaline circulation
* shutdown
* Upwelling
* Whirlpool
* World Ocean Circulation Experiment

Tides|

* Amphidromic point
* Earth tide
* Head of tide
* Internal tide
* Lunitidal interval
* Perigean spring tide
* Rip tide
* Rule of twelfths
* Slack water
* Tidal bore
* Tidal force
* Tidal power
* Tidal race
* Tidal range
* Tidal resonance
* Tide gauge
* Tideline
* Theory of tides

Landforms|

* Abyssal fan
* Abyssal plain
* Atoll
* Bathymetric chart
* Coastal geography
* Cold seep
* Continental margin
* Continental rise
* Continental shelf
* Contourite
* Guyot
* Hydrography
* Oceanic basin
* Oceanic plateau
* Oceanic trench
* Passive margin
* Seabed
* Seamount
* Submarine canyon
* Submarine volcano

Plate
tectonics|

* Convergent boundary
* Divergent boundary
* Fracture zone
* Hydrothermal vent
* Marine geology
* Mid-ocean ridge
* Mohorovičić discontinuity
* Vine–Matthews–Morley hypothesis
* Oceanic crust
* Outer trench swell
* Ridge push
* Seafloor spreading
* Slab pull
* Slab suction
* Slab window
* Subduction
* Transform fault
* Volcanic arc

Ocean zones|

* Benthic
* Deep ocean water
* Deep sea
* Littoral
* Mesopelagic
* Oceanic
* Pelagic
* Photic
* Surf
* Swash

Sea level|

* Deep-ocean Assessment and Reporting of Tsunamis
* Future sea level
* Global Sea Level Observing System
* North West Shelf Operational Oceanographic System
* Sea-level curve
* Sea level rise
* World Geodetic System

Acoustics|

* Deep scattering layer
* Hydroacoustics
* Ocean acoustic tomography
* Sofar bomb
* SOFAR channel
* Underwater acoustics

Satellites|

* Jason-1
* Jason-2 (Ocean Surface Topography Mission)
* Jason-3

Related|

* Argo
* Benthic lander
* Color of water
* DSV Alvin
* Marginal sea
* Marine energy
* Marine pollution
* Mooring
* National Oceanographic Data Center
* Ocean
* Ocean exploration
* Ocean observations
* Ocean reanalysis
* Ocean surface topography
* Ocean thermal energy conversion
* Oceanography
* Pelagic sediment
* Sea surface microlayer
* Sea surface temperature
* Seawater
* Science On a Sphere
* Thermocline
* Underwater glider
* Water column
* World Ocean Atlas

* Category
* Commons

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