1. Ocean Currents, Waves, and Tides Chapter 11 & 12 (Highways in the Sea; Waves and Tides)
Oceanography 2014

2. Ch 11 Key Vocabulary
Ocean Current continuous, directed movement of seawater generated by the forces acting upon it
Countercurrents
Upwelling
Downwelling
El Nino p11-22
Sea Level
La Nina p11-24
Pressure Gradient Force
Deep Circulation
Gyre
Contour Currents
Ekman Transport
Ocean Conveyor Belt
Friction Depth
Doppler Shift
Geostrophic Current

3. Background Vocabulary (Chapter 10) Coriolis Effect
Trade Winds prevailing pattern of easterly surface winds found in the tropics
Westerlies prevailing winds in the middle latitudes between 30 and 60 degrees latitude
Easterlies winds with an easterly component at the surface near theEarth's poles, usually at latitudes more than 60 degrees
Doldrums
Horse Latitudes
SCUBA Self Contained Underwater Breathing Apparatus
Ch 12 Key Vocabulary
Wavelength
Crest
Trough
Period
Wave Speed
Fully Developed Sea
Internal Ocean Waves
Storm Surge
Seiche
Tsunami

4. Currents: Highways in the Sea
Chapter 11
Currents: Highways in the Sea

5. Surface Currents Currents that are 0-400 meters deep
Tend to flow right in the N hemisphere and left in the S hemisphere (Coriolis Effect)
Caused by:
Wind
Cause changes in sea level across horizontal distances
Differences in density
Also causes change across horizontal distances
More dense water sinks below less dense water

7. Gyres Combination of currents creating a circular flow
Example: North Atlantic Gyre
Westerlies pushing water eastward along the upper latitudes of the Atlantic
Trade winds pushing westward near the equator
Coriolis effect

8. The 5 Major Ocean Gyres

9. Ekman Transport
Motion of the water column down to friction depth (90o right in N hemisphere and 90o left in S hemisphere)
Currents due to friction with the wind shift to right or left
Result of the Coriolis Effect
Ekman Spiral: thin layers of water flowing in a direction caused by the layer above down to friction depth (deepest point friction from wind affects water movement)

10. Boundary Currents
Currents with characteristics determined by the presence of a coastline
Western boundary currents (occur along the eastern continental coasts)
Gulf Stream
Eastern boundary currents (occur along the western continental coasts)
Canary Current
Characteristic
Western
Eastern
Temperature
Warm
Cold
Width
Narrow
Wide
Depth
Deep
Shallow
Volume
High
Low
Speed
Fast
Slow
Direction
Toward Poles
Toward Equator

11. Special Current Types
Counter-currents: current that flows in a direction opposite of the adjacent current
Upwelling
Upward vertical current bringing deep water to the surface
Occurs when wind blowing parallel to the shore pushes surface water out to sea (due to Ekman transport)
Downwelling:
Occurs when surface water is forced downward at the shoreline
Occurs when Ekman transport causes surface water to flow toward the shore

12. Deep Currents
Water motion caused by mixing water of different densities
Ocean is stratified into different layers

13. Five Primary Water Masses
Surface Water
meters deep
Central Water
-Extends into the thermocline
-Depth Varies with latitude
Intermediate Water
-To about 1500 meters deep
Deep Water
-Below Intermediate, but does not contact ocean bottom
Bottom Water
-In contact with sea floor

14. Ocean Conveyor Belt
Constant motion in the ocean = global ocean conveyor belt
Due to thermohaline currents:
Cold, salty water is dense and sinks to the bottom of the ocean
Warm water is less dense and rises to the surface
It takes almost 1,000 years for the conveyor belt to complete one “cycle.”

15. Process of the Ocean Conveyor Belt
“Starts” in the Norwegian Sea -Warm water from the Gulf Stream heats the atmosphere in the cold northern latitudes -This loss of heat to the atmosphere makes the water cooler and denser, causing it to sink to the bottom of the ocean
As more warm water is transported north, cooler water sinks and moves south to make room for the incoming warm water
This cold bottom water flows south of the equator all the way down to Antarctica
Eventually, the cold bottom waters are able to warm and rise to the surface, continuing the conveyor belt that encircles the globe

17. Chapter 12
Waves & Tides

18. Tides Daily variations in the ocean’s sea level Causes:
Vary by location
Causes:
Result of the gravitational pull of the moon (and to some degree, also the Sun)
Pulls the ocean into a huge wave with a wavelength the size of the entire ocean basin
Equilibrium Theory
Isaac Newton: the Sun and moon create two opposite bulges on each side of the Earth – each rotate around the Earth as the Sun and moon change position
As bulge moves toward coast, tides rise
As bulge moves away from coast, tides fall

19. Dynamic Theory of Tides
Pierre-Simon Laplace modified Newton’s theory because it was too simple to explain everything about tides on Earth
More than 2 tidal bulges
Tides occur in a pinwheel-shaped, standing-wave pattern
In addition to lunar and solar gravity, this theory accounts for:
Imperfect shape of Earth
Seasons
Shape of Ocean Basins
Coriolis Effect

20. Extreme Tides Bay of Fundy
Differ in volume by as much as 100 km3 (that is more than 4x the volume of all the rivers in the world combined)
Demonstrates that tides are much more complex that Newton’s simple model.

21. Waves Wave: transmission of energy through matter
Three types of waves in all matter:
Longitudinal
Transverse
Orbital
Ocean Waves
Only in fluid – energy moves a fluid in a circular motion as it passes

22. Causes and Characteristics
Created by “disturbing forces”
Intensity and duration of forces determine wave characteristics
Disturbing forces include
Wind
Changes in gravity
Seismic Activity
Movement of water is resisted by “restoring forces”
Gravity
Coriolis Effect
Surface Tension

23. Wave Classification Deep-water Waves Transitional Waves
Shallow-Water Waves

24. Internal Waves Occur within different density layers
Move slowly compared to surface waves

25. Destructive Waves Storm Surge Seiche (pronounced SAY-sh) Tsunami
Forms when high winds push water into shore
Seiche (pronounced SAY-sh)
Motion of water in lake or bay rocking back and forth due to earthquake or very strong wind
Tsunami
Sudden movement of water caused by a landslide, iceberg falling into the sea, or Earthquake

26. Waves/Currents/Tides
Oceanography Feb 6, 2014
Waves/Currents/Tides
What do you think causes tides?
List 2-3 facts you already know about waves.

27. Name the 5 major ocean gyres.
Oceanography Feb 11, 2014
Gyres
What is a gyre?
Name the 5 major ocean gyres.

28. What is the Ocean Conveyor Belt?
Oceanography Feb 18, 2014
Vocab Review
What is the Ocean Conveyor Belt?
The average level of the ocean between high and low tide is called what?
What type of circulation is caused by mixing water masses of differing densities?
What is Ekman Transport?
What is El Nino?

29. What is El Nino? -Rearrangement of high and low pressure systems
Oceanography Feb 18, 2014
Vocab Review Answers
What is the Ocean Conveyor Belt? -Constant motion of the ocean due to connected currents worldwide
The average level of the ocean between high and low tide is called what? -Sea Level
What type of circulation is caused by mixing water masses of differing densities? -Deep Circulation
What is Ekman Transport? -Motion of water due to wind motion that causes spiraling motion down to friction depth
What is El Nino? -Rearrangement of high and low pressure systems