- 1. Ocean CirculationThis image shows the abundance of life in
the sea, measured by the SeaWiFS instrument aboard the Seastar
satellite.Dark blue represents warmer areas where there is little
life due to lack of nutrients, and greens and reds representcooler
nutrient-rich areas.The nutrient-rich areas include coastal regions
where cold water rises from the sea floor bringing nutrients along
andareas at the mouths of rivers where the rivers have brought
nutrients into the ocean from the land.
2. Chapter Overview Ocean currents are moving loops of water.
Surface currents are influenced by major wind belts. Currents
redistribute global heat. Thermohaline circulation affects deep
currents. Currents affect marine life. 2011 Pearson Education, Inc.
3. What creates ocean currents? 4. Types of Ocean Currents Surface
currents Wind-driven Primarily horizontal motion Deep currents
Driven by differences in density caused bydifferences in
temperature and salinity Vertical and horizontal motions 2011
Pearson Education, Inc. 5. Measuring Surface Currents Direct
methods Floating device trackedthrough time Fixed current meter
Indirect methods Pressure gradients Radar altimeters Doppler flow
meter 2011 Pearson Education, Inc. 6. Global Surface Current Flow
2011 Pearson Education, Inc. 7. Measuring Deep Currents Floating
devices tracked through time Chemical tracers (inadvertently added)
Tritium (radioactive isotope of H produced by nuclear bomb tests in
1950s and 1960s ) 2011 Pearson Education, Inc. 8.
Chlorofluorocarbons (freons) 9. Characteristic temperature and
salinity 10. Argo - free drifting device that move vertically and
measuretemperature, salinity, and other water characteristics of
the upper 2000meters (6600 ft) of the ocean. Once deployes, each
float sinks to aparticular depth, drifts for up to 10 days
collecting data, then resurfacesand transmits data on its location
and ocean variables. 2011 Pearson Education, Inc. 11. Surface
Currents Occur above pycnocline Frictional drag between wind and
ocean Generally follow wind belt pattern Other factors:
Distribution of continents Gravity Friction Coriolis effect 2011
Pearson Education, Inc. 12. Subtropical Gyres Large, circular loops
ofmoving water Bounded by: Equatorial current Western
Boundarycurrents Northern or SouthernBoundary currents Eastern
Boundarycurrents Centered around30 degrees latitude 2011 Pearson
Education, Inc. 13. Five Subtropical Gyres1. North Atlantic
Columbus Gyre2. South Atlantic Navigator Gyre13. North Pacific 3
Turtle Gyre 544. South Pacific Heyerdahl Gyre25. Indian Ocean Majid
Gyre 2011 Pearson Education, Inc. 14. Subtropical Gyres and
Currents 2011 Pearson Education, Inc. 15. Subtropical Gyre
CurrentsFour main currents flowing into one another: Equatorial
Currents North or south Travel westward along equator 2011 Pearson
Education, Inc. 16. Subtropical Gyre Currents Western Boundary
Currents warm waters 2011 Pearson Education, Inc. 17. Subtropical
Gyre Currents Northern or Southern Boundary Currents easterly water
flow across ocean basin 2011 Pearson Education, Inc. 18.
Subtropical Gyre Currents Eastern Boundary Currents cool waters
2011 Pearson Education, Inc. 19. Gyres and Boundary Currents 2011
Pearson Education, Inc. 20. Other Surface Currents Equatorial
Countercurrents eastward flow betweenNorth and South Equatorial
Currents Subpolar Gyres Rotate opposite subtropical gyres Smaller
and fewer than subtropical gyres 2011 Pearson Education, Inc. 21.
CurrentOcean Basin Location (N, S, E, W)General Temp Flow
DirectionWind -Driven Ocean Surface Currents (Warm or Cool)of the
World Map relative to Equator (Away or Towards?)Gulf StreamAlantic
WestWarm Away 22. Ekman Spiral Surface currents move atan angle to
the wind. The Ekman spiraldescribes speed anddirection of
seawaterflow at different depths. Each successive layermoves
increasingly to theright in the NorthernHemisphere Coriolis effect
2011 Pearson Education, Inc. 23. Ekman Transport Average movement
ofseawater underinfluence of wind 90 degrees to right ofwind in
Northernhemisphere 90 degrees to left ofwind in Southernhemisphere
2011 Pearson Education, Inc. 24. Geostrophic Flow Ekman transport
pilesup water withinsubtropical gyres. Surface water flowsdownhill
and to theright. Geostrophic flow balance of CoriolisEffect
andgravitational forces Ideal geostrophic flow Friction
generatesactual geostrophicflow 2011 Pearson Education, Inc. 25.
Western Intensification Top of hill of water displaced toward west
dueto Earths rotation Western boundary currents intensified in
bothhemispheres Faster Narrower Deeper Warm Coriolis Effect
contributes to western intensification 2011 Pearson Education, Inc.
26. Eastern Boundary Currents Eastern side of ocean basins Tend to
have the opposite properties of Western Boundary Currents Cold Slow
Shallow Wide 2011 Pearson Education, Inc. 27. Eastern and Western
Boundary Currents 2011 Pearson Education, Inc.