The document summarizes key concepts in oceanography, including: 1) The ocean covers 71% of the Earth's surface and is divided into four major basins. It contains 97% of the planet's water and influences climate regulation, oxygen production, and heat storage. 2) Ocean currents are driven by prevailing winds and the Coriolis effect, forming surface gyres and deep circulation currents. The global ocean conveyor belt involves sinking of dense water masses. 3) Ocean properties vary with depth, forming three layers - a warm mixed surface layer, a thermocline of rapid temperature drop, and cold deep water below. Temperature, salinity, and pressure interact to influence ocean density stratification.

1. The Blue Planet
71% of the Earth’s surface covered by the global ocean
Oceanographers divide the world’s oceans into 4 major basins

2. Why Study the Ocean?
o More than 97% of the planet’s
water and living space is contained in
the ocean
o Most of our oxygen comes from
the ocean
o The ocean’s help to stabilize earth’s
temperature
o Top 2.5 meters of the ocean hold as much
heat as our entire atmosphere (water has
high heat capacity!)
o Rising sea levels and changing ocean
chemistry (ocean acidification) will affect
coastal populations and marine life
Video: Exploring the Oceans (National Geographic)

3. Oceanography
o Prevailing Winds & Surface Currents
o Ocean Chemistry (salinity, dissolved
gases)
o Temperature & Layered Structure of
Ocean
o Deep Ocean Circulation
o El Nino & La Nina

4. Sea Surface Temperatures
Ocean and Atmosphere act as Giant Heat Transfer System:
- Warm air/water towards the poles
- Cooler air/water towards the equator

5. Surface Currents
Streams of water that flow horizontally in upper level of ocean;
develop from friction between surface & prevailing winds

6. Prevailing Winds: global winds, a wind that consistently
blows from one direction more than from another (e.g. trade
winds, westerlies)

7. Factors Affecting Prevailing Winds
• Unequal Heating of earth leads
to pressure differences
• Pressure Differences - Winds
always blow from high air
pressure to a low air pressure
but are deflected by the Coriolis
Effect.
• Coriolis Effect = Earth’s rotation
causes free moving objects (like
air and water) to be deflected
– To the right in the Northern
Hemisphere
– To the left in the Southern
Hemisphere
• Friction with surface slows air
movement

8. Prevailing Winds
• Air heated most at equator, rises, drops moisture, low pressure at
surface (rainforests)
• Doldrums – little surface wind
• Rising air diverges in upper troposphere, cools
• Dry air sinks at 300
, higher pressure warms air as it approaches
surface (deserts)
• Horse latitudes – little surface wind
• Trade winds blow from high pressure at 300
to low pressure at
equator, but deflected by Coriolis
• Northeast trade winds in northern hemisphere
• Southeast trade winds in southern hemisphere
• Westerlies blow from high pressure at 300
toward lower pressure at
600
, deflected by Coriolis
• Southwesterlies in northern hemisphere
• Northwesterlies in southern hemisphere
• Air sinks at poles, creating high pressure and cold deserts
• Polar easterlies blow from high pressure at poles to lower pressure
at 600

9. Vocab for Surface Currents:
• Surface Ocean Currents- giant streams of water in
the upper level of the ocean driven by the
prevailing winds.
• Gyres- huge circles of moving water (several
currents joined together) as a result of the wind
belts and the Coriolis Effect
• Coriolis effect- the apparent deflective force of
Earth’s rotation on all free-moving objects
(atmosphere and oceans) deflection is to the right
in the N. hem. and to the left in the S. Hem.

10. Factors that Influence Surface Currents:

11. Ocean Circulation

12. Nike Shoes as
“Drift Meters”
• 1: 60,000 Nike shoes spilled, May 27, 1990
2: 250 recovered, March 26, 1991
3: 200 recovered, May 18, 1991
4: 100 recovered, January-February 1991
5: 200 recovered, November-December 1990
6: 200 recovered, February-March 1991
7: 150 recovered, April 4, 1991
8: 200 recovered, May 9-10, 1991
9: several recovered, January-March 1993

13. o Common on West coast of N.A., S.A.,
and Africa
o Brings nutrient-rich deep water to the
surface & provide productive fish
habitat
• Where do the nutrients come from?
• How does this process affect marine life
(the biosphere)?
Upwelling - Rising of cold water from deeper layers to
replace warmer surface water
Upwelling Animation

14. Salinity – amount of dissolved solids (salts) in seawater
Average ocean salinity is 35 parts per thousand (ppt). For every
1000g of water, there would be 7 teaspoons of salt
965g water
35g solids
Where do
the salts in
the water
come from?
Ocean Chemistry

15. Factors Influencing Salinity
What changes salinity, the addition/removal of water or salts?

16. Ocean Salinity
• Surface salinity varies by latitude and local conditions
• Why is salinity so high in the Mediterranean Sea (~38ppt)?
• Highest ocean salinities in the centers of ocean basins
(more evaporation by prevailing winds)

17. Dissolved Gases in Seawater
o Ocean exchanges gases with the atmosphere to
maintain balance in concentrations
e.g., nitrogen (N2), oxygen (O2) and carbon dioxide (CO2)
o Dissolved oxygen and CO2 needed for marine life
o Gases dissolve more easily in cold water.
As oceans temperatures increase, how will this affect the ocean’s
ability to hold CO2?
Video: Southern Ocean Carbon Sink (sciencelearn.org)

18. Three Layered Structure of the Ocean
• Top layer =
____________
• Middle layer =
__________________
• Bottom layer =
_______________
• According to this graph
could water at the
surface mix with water
at 5000 m? Explain.

19. Thermocline
• Thermocline -
Located below the
warm, surface, mixed
layer and above the
cold, deep water it is
the zone of rapid
temperature decline.
• Why does Temp.
decrease with
depth?

20. Variations in Depth of Thermocline
• If winds are strong, top
of thermocline is (deep
or shallow)
__________.
• If water is cloudy (b/c of
suspended sediment,
top of thermocline is
(deep or shallow)
___________.

21. Temperature gradient with Latitude
• Why is the thermocline absent at high latitudes (poles)?
• Explain a possible difference between the mid-latitude
summer and winter temperature curves?

22. Ocean Density (Density = mass per unit volume)
How does ocean density
vary by latitude?
Why is the pycnolcine
absent at the poles?
Density of seawater is
affected by:
•Pressure
•Temperature
•Salinity

23. Salinity vs Depth
• Salinity increases
with depth? Why?
• Halocline: layers
where salinity
increases sharply
www.bigelow.org

24. Sea Ice• Freezing point of seawater -2
deg. C
• Adding salt to water lowers the
freezing point.
• Pack ice - A floating layer of sea
ice that completely covers the
ocean surface. (Arctic Ocean
covered for most of the year)
• Is there a thermocline at the
north pole?
• Is the 3-layered structure
present?
• Is salinity higher or lower at the
poles?

25. Temp and Salinity affect Seawater
Density
Which has a greater effect on density? Explain.

26. Deep Currents – Driven By Density
• Cold, dense currents that move more slowly than the surface
currents. Deep currents have a strong vertical component
• Produced as cold, dense water at the poles sinks and flows
beneath warmer ocean water toward the equator.
• Cold = more dense
• Higher salinity = more dense

27. Deep Currents
• Antarctic Bottom
Water (-2 deg. C,
Salinity = 35 parts per
thousand) (cold and
salty = densest water
in ocean)
• North Atlantic Deep
water (Not as cold
and salty so not as
dense

28. Deep Currents
http://myweb.cwpost.liu.edu/vdivener/

29. Global Ocean Conveyer Belt
Video: Global Ocean Conveyer Belt
Constantly moving system of deep ocean circulation
driven by temperature and salinity

30. Ocean Circulation

32. Salinity
• What latitudes
have the highest
surface salinity?
• Why?
• What latitudes
have the lowest
surface salinity?
• At 30 degrees N
how does
salinity change
from the surface
to the deep?
Why?