1. Chapter 16 The Dynamic Ocean

2. 16.1 Ocean Circulation

3. Surface Circulation
Ocean currents are masses of ocean water that flow from one place to another
Surface currents – movements of water that flow horizontally in the upper part of the ocean’s surface
Develop from friction btw the ocean and the wind that blows across its surface

4. Gyres
Huge circular moving current systems dominate the surfaces of the oceans
5 Main ocean Gyres
N. Pacific Gyre
S. Pacific Gyre
N. Atlantic Gyre
S. Atlantic Gyre
Indian Ocean Gyre

5. Coriolis effect – deflection of currents away from their original course as a result of Earth’s rotation
Due to Earth’s rotation, currents are deflected to the right in the N. Hemisphere & to the left in the S. Hemisphere
4 main currents within each gyre

6. Ocean Currents & Climate
When currents from LL regions move into HL they transfer heat from warmer to cooler areas on Earth
As cold water currents travel toward the equator, they help moderate the warm temperatures of adjacent land areas
Play a big role in maintaining Earth’s heat balance

7. Upwelling
Rising of cold water from deeper layers to replace warmer surface water
Wind-induced vertical movement
Brings greater concentrations of dissolved nutrients to the ocean surfaces

8. Deep – Ocean Circulation
Density currents – vertical currents of ocean H2O that results from density differences in the H20 masses
Increase in seawater density can be caused by a decrease in temperature or an increase in salinity

9. A Conveyor Belt Warm H20 flows toward poles
Temperature drops & salinity increases
Density increases
Dense H20 moves toward equator
Cold, deep water upwells
Upwelled H20 warms
The cycle repeats

10. 16.2 Waves & tides

11. Waves Energy traveling along the boundary btw ocean and atmosphere
Most ocean waves obtain their energy & motion from wind
Top of wave = crest
Trough = separate crests
Wave Height = vertical distance btw trough & crest

12. The height, length, & period depend on 3 factors:
Wavelength = horizontal distance btw 2 successive crests (or 2 successive troughs)
Wave period = the time it takes one full wave (one wavelength) to pass a particular spot
The height, length, & period depend on 3 factors:
Wind speed
Length of time the wind has blown
Fetch (distance that the wind has traveled across open H20)

14. Circular orbital motion allows energy to move forward through the H20 while the individual water particles that transmit the wave move around in a circle
When waves approach shore, H20 becomes shallower & influences wave behavior (“feels the bottom” at depth = to half of its wavelength)

16. Tides Tide-Causing Forces Tidal Cycle
Results from the gravitational attraction exerted upon Earth by the moon (and the sun)
Gravity & Inertia produce tides
Gravity attracts the Earth & moon
Inertia = tendency of moving objects to continue in a straight line (keeps Earth & moon from crashing into each other
Tidal range – difference in height btw successive high & low tides
Spring tides – tides that have the greatest tidal range due to the alignment of the Earth – moon – sun
Neap tides – lowest tidal range
Each month = 2 spring tides & 2 neap tides

17. Tidal Patterns 3 main tidal patterns Diurnal Tides Semidiurnal Tides
1 high tide & 1 low tide each tidal day
Semidiurnal Tides
2 high tides & 2 low tides each tidal day
Mixed Tides
Large inequality in high water heights, low water heights, or both

19. 16.3 Shoreline processes & features

20. Forces Acting on the Shoreline
Waves along the shoreline are constantly eroding, transporting, & depositing sediment
Wave Impact
Abrasion
Wave Refraction
Bending of waves
Wave energy is concentrated against the sides & ends of headlands that project into the H20, whereas wave action is weakened by bays

21. Longshore current – near shore current that flows parallel to the shore
Turbulence allos longshore currents to easily move the fine suspended sand & to roll larger sand & gravel particles along the bottom

22. Erosional Features
Shoreline features that originate primarily from the work of erosion
Sediment that is transported along the shore & deposited in areas where energy is low produce depositional features
Wave-Cut Cliffs & Platforms
Sea Arches & Sea Stacks

24. Depositional Features
Spits
Bars
Tombolos
Barrier Islands – narrow sandbars parallel to the coast (separate from coast) (3-30 km offshore)

26. Stabilizing the Shore
Groins, breakwaters, & seawalls are some structures built to protect a coast from erosion or to prevent the movement of sand along a beach
Can be built parallel to shoreline
Beach nourishment is the addition of large quantities of sand to the beach system