1. Bell Ringer
In your own words, define the following terms. In addition to a definition, discuss WHY each might be important.
Ocean circulation
Current
Gyre
Wave
Tide

2. MARINE BIOLOGY Essential Question:
How do Surface and Thermocline Circulation affect the Ocean?
Learning Goals:
Learn the components of Superficial and Thermocline Circulation
Agenda:
Bell Ringer
Collect Homework
Chapter 3 (Part 3)
Classwork
CNN/10 (3rd and 7th only)
Upcoming:
Chapter 3 (Part 4)
Chapter 3 Test: 10/9 (B) & 10/10 (A)

3. Ocean Circulation – Surface & Thermocline (Part 3)
Chapter 3
Ocean Circulation – Surface & Thermocline
(Part 3)

4. Ocean Circulation
Circulation can occur as waves, tides, currents and gyres.
Circulation within the ocean is significantly driven by wind patterns.
Winds are ultimately driven by sunlight energy.

5. Ocean Circulation (Cont.)
As sunlight heats air, air rises.
Hot air is less dense
Cooler air rushes in to take the place of air that has risen.
This movement is the source of winds.
– Bill Nye

7. The Winds Trade Winds: Located from the equator (0° - 30°)
Westerly’s : Located in the Mid latitudes (30° - 60°)
Easterlies : Located at the poles (60° - 90°)

9. Coriolis Effect
Winds and the currents they drive are affected by the Coriolis effect.
Because the earth spins continuously, anything that passes over the earth is deflected.
In the NORTHERN Hemisphere wind is deflected to the RIGHT!
In the SOUTHERN Hemisphere wind is deflected to the LEFT!

10. Currents Currents are also a product of the wind.
Current can be in surface layers of deeper water layers
This deflection often causes currents to travel in circular patterns called gyres.
– spiral

11. Surface Currents
All exposed surfaces of the ocean are subject to currents produced by the wind.
Currents produced by the wind move at a 45° angle to the right due to the Coriolis effect
This surface water current tugs on lower segments of water leading to an spiral (“Elkman Spiral”)
Effect of the wind decreases with depth and is NOT felt passed a few hundred meters.

12. Elkman Spiral

13. Elkman Layer & Transport
Elkman Layer: Upper Part of the Water Column affected by wind
Elkman Transport: Microlayers moving together to produce a net movement of water 90° from the wind direction.

14. Equatorial Currents
Due to the Trade wind movement towards the equator the current produced at the equator is parallel with the equator.
The equatorial current moves along the equator East to West against the rotational spin of the earth

15. Major Ocean Surface Currents

16. Accidental Flotsam Current Study
January (1992) Cargo ship in Pacific Ocean hit a wave & lost cargo.
It was carrying toys from China to the United States.
29,000 Plastic Ducks among others
Toys began washing up on shores around the world.
November (1992): Sitka, Alaska
1995 : Hawaii, Japan, Bering Sea
2000 : East coast of United States
Maine, Massachusetts
2007 : England

17. Accidental Flotsam Current Study
On world map
Write name and period #
Sketch possible paths taken by the toys, where in the Pacific might they have been released?
Describe in words how the toys could have made it to England.
Could the toys journey all the way around the world? Why or why not?
For homework, find the actual passage taken by the ducks and superimpose it onto your world map (use a different color, etc.)

18. Thermohaline Circulation
Much of the Ocean surface waters are partially isolated from deeper waters due to density (temperature and salinity)
Because denser sea water sinks, the ocean is usually stratified (layered) with the denser water at the bottom and the less dense at the surface.
Deep water: Cold and dense
Surface water : Warm and less dense.

19. Three Layered Ocean Surface Layer Intermediate Layer Deep Layer
100 – 200 meters (m) deep
Mostly mixed by winds & waves
Intermediate Layer
200 – 1000 meters (m) deep
Deep Layer
1000 meters (m) + deep
Thermoclines
Transitions from warm to cold waters.
Boundaries between layers
Main thermocline is in the intermediate layer.

20. Stability and Overturn
Much of the water column is stable.
Stability is achieved through large differences in density between shallow and deeper water!
Caused by a water column that has lost stability.
Surface water becomes more dense and downwelling occurs.
Downwelling occurs mostly during winter due to cold surface temperatures and water cold glacial water run off.
Upwelling is the opposite.

21. The Great Ocean Conveyor
Water settles in the column based on its density.
Complete downwelling occurs only in the Atlantic South of Greenland & just North of Antartica.
This is only temporary and drives the global thermohaline circulation.
The oceans completely mix every 4000 years.