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Unit 7 Sonar

Unit 7 Sonar. Sonar. Active remote sensing Sound pulses developed in WWII to detect submarines Current applications: Sea floor imaging Geology Bathymetric data Underwater habitats Shipwrecks Geopolitics. NOAA data provided to Google earth. Pamlico Sound, N Carolina Interpolated data

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Unit 7 Sonar

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  1. Unit 7 Sonar

  2. Sonar • Active remote sensing • Sound pulses developed in WWII to detect submarines • Current applications: • Sea floor imaging • Geology • Bathymetric data • Underwater habitats • Shipwrecks • Geopolitics

  3. NOAA data provided to Google earth • Pamlico Sound, N Carolina • Interpolated data • Interpolated?? Google earth blog: http://www.gearthblog.com/blog/archives/2007/01/noaa_releases_estuar.html

  4. Principles of sonar • Waves can only travel through an elastic material, eg air , water, earth, not through space. • Uses through earth and water

  5. Sonar • The intensity or strength of the returning acoustic signal is primarily controlled by the slope of the seafloor and seafloor materials • Note the shadow … shadows also occurs with radar data

  6. NOAA Sonar data NOAA is involved • Bathymetry • Underwater habitats • Fish management • http://www.youtube.com/watch?v=-fAAxEIFeLU

  7. Sonar seafloor mapping (USGS and NOAA) • USGShttp://walrus.wr.usgs.gov/pacmaps/ • See Puget Sound • Imagery plus data • Rationale: • identifying areas of erosion and deposition on the continental shelf • locating areas of geohazards (such as slumps and faults) • locating pathways for movement of sediment and pollutants • Extent of the continental shelf (geopolitics)

  8. Submarine canyon Images like this for: Engineering (eg pipeline locations, planning) Dredging Environmental hazards (cap over pollution laden sediments)

  9. Geopolitics: United Nations Convention on the Law Of the Sea (UNCLOS) • Defined maritime boundaries • Article 76 allows a maritime nation to extend its jurisdiction beyond 200 nm of the coast to exploit resources on or below seabed of the land’s natural extension. • Need to define ‘natural extension’ • Need to locate edge of its continental margin

  10. Continental margin Coastal relief model bathymetric and topographic chart from multibeam sonar

  11. Arctic Ocean Basin Ownership • Land grab, in part on basis of extent of the continental shelf • http://www.sciencedaily.com/releases/2008/08/080805192723.htm

  12. Russian Efforts 2007: Russia plants flag at North Pole Basis for their claim: the Lomonosov Ridge http://www.npr.org/player/v2/mediaPlayer.html?action=1&t=1&islist=false&id=139577789&m=139666494

  13. Shipwrecks: History, fame and $ • El Nuevo Constante, sank in 1766 lay in only about 19 feet of water of wreck off Constance Bayou, Louisiana. However, divers could not see the wreck because of mud. The liquid mud formed a thick soup extending 2 or 3 feet above the sea bottom. http://www.crt.state.la.us/archaeology/NUEVO/hist.htm

  14. More recent wooden ship remains • Side scan sonar image of the Frank A. Palmer and Louise B.Crary. (Courtesy of NOAA/SBNMS and NURC-UConn.) • Sunk 1902, Massachusetts

  15. And $, see Odyssey Marine exploration http://www.shipwreck.net/index.php

  16. Further applications • Fish detection (more economic fishing and fish stock collapse?) • Vessel detection

  17. Fish detection: fish finders • Any number of sophisticated sonar devices • Find fish faster: less fuel/time needed “Fish finder manufacturers are competing at a rapid pace to have the most innovative technology available to fishing professionals and amatuer fishermen alike. The technology today offers color screens defining fish, bottom configurations, thermoclines, bait fish, structure and more. Additionally, many fish finders include GPS navigation systems allowing one to mark the location of favorite fishing spots” http://www.aa-fishing.com/fish-finders.html

  18. But: More efficient fishing technology is related to fish stock collapse • A major international scientific study released in 2006 in Science found that about one-third of all fishing stocks worldwide have collapsed (with a collapse being defined as a decline to less than 10% of their maximum observed abundance), and that if current trends continue all fish stocks worldwide will collapse within fifty years • Bigger vessels, better nets, and new technology for spotting fish are not bringing the world's fleets bigger returns: the global catch fell by 13% between 1994 and 2003

  19. Over-fishing means UK trawlers have to work 17 times as hard for the same fish catch as 120 years ago (http://www.bbc.co.uk/news/10096649)

  20. Stock collapse

  21. Mitigating fish stock collapse • In the recent past we have taken more fish than the oceans can sustain • Are we still? • Growing movement to establish marine sanctuaries • Also fish farming (which brings its own set of concerns)

  22. Vessel detection: Problems with high-powered sonars used in underwater vessel detection • http://www.sciencedaily.com/releases/2008/10/081006112057.htm • Marine mammals are dying in areas where powerful sonars are used (military operations) • People are working to understand marine mammal strandings and their relationship to sonar use • Appears to produce an effect similar to the ‘bends’ in divers

  23. Can’t end on something so grim... so … • Sonar of Bonneville dam 2007 • Sonar surveys spotted a vast pile of rubble in the Columbia River • http://blog.oregonlive.com/breakingnews/2008/05/_when_sonar_surveys_spotted.html • Thousands of sturgeon some over 14 ft long!

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