Acoustical oceanography

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.

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 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[]

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

References[]

^ Garrison, Tom. Essentials of Oceanography. 6th ed. Pacific Grove, CA: Brooks Cole, 2012. p.79.
^ Kunzig, Robert. Mapping the Deep: The Extraordinary Story of Ocean Science. New York: Norton 2000. p. 40-41.
^ Stewart, Robert. Introduction to Physical Oceanography, University Press of Florida, 2009 p. 28.
^ "Oceanography". Scholastic Teachers.
^ "Tools of the Oceanographer". marinebio.net.
^ "Technology used". noc.ac.uk. Archived from the original on 2015-01-21. Retrieved 2015-01-21.
^ ^a ^b C. S. Clay & H. Medwin, Fundamentals of Acoustical Oceanography (Academic, Boston, 1998).
^ E. J. Simmonds & D. N. MacLennan, Fisheries Acoustics, Second Edition (Blackwell, Oxford, 2005).

External links[]

ASA Acoustical Oceanography Technical Committee

[Garrison2012-1] 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.

[5] "Tools of the Oceanographer". marinebio.net.

[6] "Technology used". noc.ac.uk. Archived from the original on 2015-01-21. Retrieved 2015-01-21.

[ClayMedwin-7] 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).

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v t 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 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 nonlinearity 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 current Ocean dynamics Ocean dynamical thermostat Ocean gyre Princeton ocean model Rip current Subsurface currents Sverdrup balance Thermohaline circulation shutdown Upwelling Wind generated current 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 Knoll 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 Outline of oceanography Pelagic sediment Sea surface microlayer Sea surface temperature Seawater Science On a Sphere Thermocline Underwater glider Water column World Ocean Atlas
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