An Introduction to Oceanography

Lecture 2 – MR1008

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Definition

• The study of the ocean, embracing and integrating all knowledge pertaining to the ocean's physical boundaries, the chemistry and physics of sea water, and marine biology.

www.weather.com/glossary/o.html

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Definition

• The scientific study and exploration of the oceans and seas in all their aspects, including all processes in the oceans and interactions and relations with Earth.

www.reefed.edu.au/glossary/o.html

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Oceanography - summary

• Oceanography is the study of the deep sea and shallow coastal oceans: their biology, chemistry, geology and physics together make oceanography a richly interdisciplinary science.

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Why is Oceanography important?

• The importance of the oceans to physical climate, food supplies and biological stability

• An extra dimension to human activity

And……….

• Long-term habitability of Earth

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Origins of Oceanography• The scientific ancestors of oceanographers

range widely

• Physical oceanography harks back to the polar explorers of the 19th Century and the physicists who developed the study of flowing fluids.

• Techniques of physics and applied mathematics are used by physical oceanographers for the study of the physical ocean and climate.

• An understanding of physics has yielded significant contributions to biology, chemistry and geophysics, where understanding at the molecular level is sometimes the key to discovery.

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Origins of Oceanography

• Biological oceanographers were naturalists cataloguing the life-forms of the sea

• The Geology and Geophysics of the ocean owes much to ideas of plate tectonics, verified 'at sea' by the magnetic striping of seafloor that emerges from spreading center ridges, as recently as the 1960s

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Copyright Skinner & Porter 1987

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Origins of Oceanography

Chemical oceanography developed • in part as a service to biology, through analyses of

nutrients and dissolved gases relating to life in the sea.

• Chemistry in oceanography also developed through simple curiosity about the circulation: trace chemicals (dissolved gases, natural nutrients, radioactive products of nuclear weapons testing, trace metals) are transported with the ocean circulation and exchanged with seabed and atmosphere

• This is a science in its own right providing a detailed picture of the ocean circulation that cannot be obtained from direct measurement of currents.

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Living Machine

• Together with the atmosphere, continents and ice-cover (the 'cryosphere'), they form a working machine, driven mostly by energy from the sun.

• Lesser amounts of energy derive from tides raised by the moon and sun and planets, and heat from the Earth's interior.

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Oceanographers and Oceans

• Oceanographers aim their work at both practical problems and basic scientific discovery

• Oceans :

– provide threats;– a bountiful diversity of food– are the reservoir of our water supply– most of the heat and carbon of the climate system– are the source of roughly ½ the respired oxygen of

the biosphere,– contain most of the remaining undiscovered natural

pharmaceuticals

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Oceanographers and Oceans

• Study of ocean life provides models for research in human illness, for example using the giant, accessible neurons of the squid.

• Techniques of classical physics are joined with modern instrumentation and computers.

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A Young Science

• Although oceanography is a relatively young science

• It is the natural setting to ask fundamental questions about the development of life, and the behavior (or misbehavior) of global climate

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Some Facts

• The oceans cover 7/10 of the Earth's surface.

• Together with the atmosphere and the 'fresh-water' sphere they make up 'fluid' Earth.

• Much of the biomass...the mass of living plants and animals...lives in the oceans, far more than on land!

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• Photosynthesis of the phytoplankton (the 'grass' of the seas) and respiration of zooplankton and larger animals (the 'cows' of the sea) are important to the global chemical balance of our oxygen-rich world

• Very roughly ½ of the primary production

of oxygen from photosynthesis, by all life on Earth, occurs in the sea. Roughly ½ of that occurs in the productive, shallow ocean near land.

Some Facts

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Some More Facts

• Coastal oceanography is also of great importance

• About 25% of global primary productivity (photosynthesis by plant life) occurs in the ocean near the coasts, and that is about one-half of the total productivity of the world ocean. 80 to 90% of the world fish catch occurs in the coastal ocean.

• Today these shallow-water ocean regions are under great stress from e.g. population increase, pollution, ballast water exchange

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What does Oceanography Entail?

• Until the 1970s the normal oceanographic expedition (time at sea) involved bringing back samples of water from the deep ocean for analysis using simple measurements:

– reversing thermometers and Nansen bottles lowered on steel cables, and triggered by dropping a weight (the 'messenger') down the wire– plankton tows in simple mesh nets– small coring devices– bottom dredges.

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Nansen Bottle

A Nansen bottle coming out of the water on a nearly mirror smooth sea.

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• Today with electronics and computers many more things can be measured.

• Physical variables like temperature and salinity are observed in this way, and there are new probes being designed that will allow electronic measurement of many chemical and biological variables.

What does Oceanography Entail?

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What does Oceanography Entail?

•Seismology and sub-seabed geophysics are being explored using 'underwater observatories‘ • Moorings, with steel or Kevlar cable extending from near the ocean surface to its bottom, have many instruments to record observations internally

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• Autonomous undersea vehicles (AUVs) propel themselves or drift with currents for years at a time.

• Satellites - Satellite oceanography is combined with other observations and with computer modelling of ocean/atmosphere circulation to give a 'best-fit' assimilation of the complete circulation. (see Regional Satellite Oceanography – Serge Victorov – Taylor and Francis)

What does Oceanography Entail?

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What does Oceanography Entail?• In the Arctic oceanographers use Icebreakers or methods of boring holes in the ice and helicopters and ski-equipped airplanes to do 'sections' across the Arctic, or to set moorings and autonomous vehicles into action.

• “Cat-Scans" using fast, small boats towing instruments that 'fly' through the water on a carefully controlled course. Acoustic waves are sent down through the water column, and their reflections off small particles in the water give a complete profile of the ocean velocity, from top to bottom.

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• Theoretical work in oceanography uses classical physics and many sub-fields of physics: for example the science of 'chaos', which involves the complex behavior of seemingly simple physical systems.

• The 'soliton', a fundamental, nonlinear wave that propagates undistorted over great distances, was discovered in oceanography and now is found in fiber-optics cables, and many physical systems

What does Oceanography Entail?

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• Computers play an intense role in physical oceanography, giving us simulations of waves and circulation based on Newtonian dynamics.

• Ocean and atmosphere are coupled together in 'climate models' and 'circulation models'; the computer models become the meeting point for observations, theory and prediction.

What does Oceanography Entail?

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Scripps Institute of Oceanography

• At Scripps, observation, measurement, and collection of samples and data are accomplished on a global scale by extensive shipboard, ground, and aerial operations, including remote sensing by satellite and the use of wide-ranging instrument networks.

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Ship, Type, Specifications & Location

R/V Roger RevelleBuilt: 1996Length: 273' Beam: 52'5" Draft (max): 17'Gross Tonnage: 3,180 long tons Displacement: 3,512 long tons Crew: 22Scientific berthing: 37Motors: Two 3,000 hp Propulsion General ElectricBow Thruster: 1,180 hp Azimuthing jetPropulsion: Two 3,000 hp Z-Drive Lips Water Capacity: 12,000 gal Incinerator: YesFuel consumption: 4,400 gal/day (transit)Speed, Cruising: 12 knotsSpeed, Maximum: 15 knotsSpeed, Minimum: variable to 0, any directionEndurance: 52 days at 12 knots (fuel)Range: 15,000 at 12 knots (fuel)Fuel capacity: 227,500 (planning)

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• Oceanography Committee (OCC)

• Chair: Einar Svendsen Area of responsibility is physical, chemical, and pelagic biological oceanography, especially in relation to the processes relevant to living marine resources and environmental quality.

• Responsiblity includes issues such as impacts of climate variability and change, and the quantification of physical, chemical and biological fluxes in coastal, shelf and open ocean areas.

• Describe, understand, and quantify the state and variability of the marine environment in terms of its physical, chemical and biological processes

ICES

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• Understand and quantify the role of climate variability and its implications for the dynamics of the marine ecosystems

• Evaluate the ecosystem consequences of contaminants and eutrophication

• Develop and improve fisheries assessment tools that utilize environmental information, consider biological and socio-economic interactions and address issues of uncertainty, risk, and sustainability

ICES

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ICES cont…

• Play an active role in the design, implementation, and execution of global and regional research and monitoring programmes

• Co-ordinate international monitoring

and data management programmes that underpin ongoing ICES core science.

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IFREMER

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Some Examples

• Seafloor

• Satellite Oceanography

• Circulation and Currents

• Geographic Information Systems (GIS)

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Seafloor

• Data collection: echo sounders and sonar

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Satellites - sea surface temperature •This image is a close up of part of the Gulf Stream.

•AVHRR sensor (Advanced Very High Resolution Radiometer) carried on a NOAA satellite (Nation Oceanic and

Atmospheric Administration)

•In this image the core of the Gulf Stream ranges between 25 and 28 deg C (77 and 82 F).

•The yellow water below the stream is about 23 deg C (73 F) and the green water off Long Island is about 14 deg C (57 F).

•The blue water around Nova Scotia is about 5 deg C (41 F)! The black line shows where the ocean is 1000m deep, (water shoreward of this line is less than 1000 meters deep and water seaward of this line is more than 1000 meters deep).

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Circulation

• Ocean circulation is the large scale movement of waters in the ocean basins.

• Winds drive surface circulation, and the cooling and sinking of waters in the polar regions drive deep circulation (Thermohaline).

• Surface circulation carries the warm upper waters poleward from the tropics.

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• Heat is dispersed along the way from the waters to the atmosphere

• At the poles, the water is further cooled during winter, and sinks to the deep ocean. This is especially true in the North Atlantic and along Antarctica

• Deep ocean water gradually returns to the

surface nearly everywhere in the ocean.

Circulation cont..

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Circulation cont..

• Once at the surface it is carried back to the tropics, and the cycle begins again. The more efficient the cycle, the more heat is transferred, and the warmer the climate.

• Due to the rotation of the Earth, currents are deflected to the right in the northern hemisphere and to the left in the southern hemisphere. This effect is known as the "Coriolis force."

• The deflection leads to highs and lows of sea level directly proportional to the speed of the surface currents.

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Circulation cont..• The changes in sea level due to currents are the

ocean topography that is observed by TOPEX/Poseidon.

• Observations of ocean topography and a knowledge of the Coriolis force permit scientists to map ocean currents using data from the satellite. Every ten days TOPEX/Poseidon produces maps of the currents everywhere in the ocean.

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Deep Sea Circulation

• Thermohaline circulation refers to the deepwater circulation of the oceans and is primarily caused by differences in density between the waters of different regions.

• It is mainly a convection process where cold, dense water formed in the polar regions sinks and flows slowly toward the equator.

• Most of the deep water acquires its characteristics in the Antarctic region and in the Norwegian Sea.

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• Antarctic bottom water is the densest and coldest water in the ocean depths. It forms and sinks just off the continental slope of Antarctica and drifts slowly along the bottom as far as the middle North Atlantic Ocean, where it merges with other water.

• The circulation of ocean waters is vitally important in dispersing heat energy around the globe. In general, heat flows toward the poles in the surface currents, while the displaced cold water flows toward the equator in deeper ocean layers.

Deep Sea Circulation

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Other Areas

• Ocean Dimensions, Shapes & Bottom Materials• Properties of Salt Water• Geography – patterns and distributions• Water, Salt and Heat budgets

• Geology• Deep Sea Fisheries• Coral Reefs

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Data Collection and Management

• ICES oceanographic data in ODV generic format

ICES Oceanographic Database and Services

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GIS

Undersea with GIS – Dawn Wright (ed.)ESRI Press

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Useful Websites

• http://www.mth.uea.ac.uk/ocean/vl/ (WWW Virtual Library)• http://www.tos.org/ (Oceanography Society)• http://www.soc.soton.ac.uk/ (Southampton Oceanography Society)• http://www.soc.soton.ac.uk/GDD/index.html (Ocean Processes)• http://www.esdim.noaa.gov/ocean_page.html (Ocean Resources)• http://oceanworld.tamu.edu/ (OceanWorld)• http://www.bio.gc.ca/welcome-e.html (Bedford Institute)• http://sio.ucsd.edu/ (Scripps Institute)• http://www.mar.dfo-mpo.gc.ca/science/ocean/remotesensing/welcome.html

(Remote Sensing)• http://www.phys.ocean.dal.ca/hotlists/Canada.html (Hotlist of

Oceanography websites)• http://www.ices.dk/ (ICES)

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References

• Oceanography, An Illustrated Guide, Wiley & Sons, New York. edited by Colin Summerhayes and Stephen Thorpe, Eds. 1998

• Science and the Seven Seas: a history of Oceanography, 1650-1900, Margaret Deacon, Academic Press, 1971.

• Why We Are Oceanographers, in Collected Works of Henry M. Stommel, Amer. Meteorological Soc. Press, 1995 (reprinted from Oceanography, vol 2, pp 48-54, 1989)

• New Eyes on the Oceans, Jennifer Ackerman, National Geographic Magazine, October 2000

• Ocean Sciences At the New Millenium, National Science Foundation, March 2001.

• Ocean Circulation - The Open University Press - Butterworth Heinemann• Descriptive Physical Oceanography - G. Pickard and W.Emery - Pergamon• Introductory Physical Oceanography - S. Pond and G.Pickard - Pergamon• Waves, Tides and Shallow-Water Processes - The Open University Press

-Butterworth Heinemann

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JournalsICES Journal of Marine Science

The ICES Journal of Marine Science publishes articles, short communications, and critical reviews that contribute to our scientific

understanding of marine systems and the impact of human activities.

The Journal serves as a foundation for scientific advice across the broad spectrum of management and conservation issues related to the marine environment. Oceanography, marine habitats, living resources, and related management topics constitute the key elements of papers eligible for publication. Integrated studies that bridge gaps between traditional disciplines are particularly welcome. The scope of the Journal has been broadened to include economic, social, and public administration studies to the extent that they are directly related to management of the seas and are of general interest to marine scientists. Proceedings of ICES-sponsored symposia constitute an integral part of the Journal and observe the standards set for regular papers. History

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Jobs on Oceanography

• Background in

– Physics– Mathematics– Chemistry– Biology– Geology...– ……coupled with an intense curiosity about

the natural world!