What percent of the earth is covered in water or land?

What percent of the earth’s water is salty or fresh?

Ocean Salinity

World Ocean Facts – which ocean is the biggest?

Area(1,000,000

km²)

Volume(1,000,000

km³)

Average Depth

(m)

Maximum Depth

(m)

Atlantic Ocean

82.4 323.6 3926 9200

Pacific Ocean

165.2 707.6 4282 11,022

Indian Ocean 73.4 291.0 3963 7460

Arctic Ocean 14.1 17.0 1205 4300

HW: What makes the ocean salty?

• Think about why the highest salinity is found near equator.

Lab Inquiry:

• How does temperature and salinity affect the density of ocean water?

Oceanic Circulation

Aim: Why causes the currents in the ocean?

Vocabulary

• Salinity• Density• Upwelling• Gyre• Currents• Thermal Expansion• Coriolis• Global Winds

Why is Ocean Circulation Important?

a. Transport ~ 20% of latitudinal heat between Equator and poles

b. Transport nutrients and organisms

c. Influences weather and climate

d. Influences commerce

e. Pollution is transported

2 kinds of circulation:

a. Surface driven currents are wind-driven and occur in the uppermost 100 m or less of ocean

b. Deep ocean currents are caused by density changes due to salinity and temperature differences. These currents produce very slow flows in deeper waters.

c. Other forces affecting currents: Coriolis effect, friction, gravity, thermal expansion, geologic shape of ocean basin and landmasses

• How fast? A few miles/hr (Gulf Stream off of Miami = 4.5 mph) How much? Total water in

ocean surface circulation = about 100 Amazon Rivers (20

million m3/s).

N. Atlantic Gyre

S. Atlantic Gyre

N. Pacific Gyre

S. Pacific GyreIndian Ocean

Gyre

Antarctic Circumpolar Current

Gyres are large circular-moving loops of water Five main gyres (one in each ocean basin):

• North Pacific• South Pacific• North Atlantic• South Atlantic• Indian

• Generally 4 currents in each gyre• Centered about 30o north or south

latitude

Current Gyres

ESRT Surface Ocean Currents pg. 4

• Color the war currents red and the cool currents blue

http://www.youtube.com/watch?v=PAQos8COqYI&feature=player_embedded

Surface Currents are created by:

1. Global Winds

2. Coriolis Effect

3. Solar Heating (temperature, density)

Global Winds pg. 14 ESRT Surface currents of ocean generally mirror

atmospheric circulation (wind) patterns

equator

Quito

Buffalo

79oW

North Pole

South Pole

N

Quito

Buffalo

equa

tor

Buffalo moves 783 mphQuito moves 1036 mph

15o

The Coriolis effect on Earth• As Earth

rotates, different latitudes travel at different speeds

• The change in speed with latitude causes the Coriolis effect

Coriolis Effect

a. The rotation of Earth causes a deflection (curve) of the winds and waters of the Earth.

• In Northern Hemisphere, curvature is to right - clockwise

• In Southern Hemisphere, curvature is to left – counterclockwise

b. Effect lessens at

equator and increases at poles

• Visualization of the Coriolis effect:• http://

www.classzone.com/books/earth_science/terc/content/visualizations/es1904/es1904page01.cfm?chapter_no=visualization

• Wind:• http://www.classzone.com/books/earth_s

cience/terc/content/visualizations/es1905/es1905page01.cfm?chapter_no=visualization

A) Idealized winds generated by air pressure differences and Coriolis Force.  B) Actual wind patterns affected by land mass distribution..

Ocean Circulation & Global Winds

Sea Surface Temperature

Thermal expansion

• Solar radiation heats the water at equator more than the poles

• Warm water expands and cool water contracts, creating a water bulge at the equator

• Gravity pulls warmer water “downhill” toward cooler water

Ocean Salinity

Increased evaporation near the equator makes the water saltier.

Global ocean circulation that is driven by differences in the density of the sea water which is controlled by temperature and salinity.

Thermohaline Circulation - The Ocean Conveyor

Equatorial to polar heat transport and water flow

LINKS:

• http://www.youtube.com/watch?v=w_8mw-1HYFg

• http://www.youtube.com/watch?v=nAq9LXLXISk

• http://www.youtube.com/watch?v=rR5TFWNLtOc&feature=related

• http://www.youtube.com/watch?v=boiFoSRq1BM&feature=related

What do Nike shoes, rubber ducks, and hockey gloves have to do with currents?

Lost at Sea

2004-2007 Barber’s Point

• “Great Pacific Garbage Patch”

• Estimate: 46,000 pieces of floating garbage/mi2.

North Pacific Subtropical Gyre

North Pacific Subtropical Gyre

135° to 155°W and 35° to 42°N

North Pacific Subtropical Gyre

http://marinedebris.noaa.gov/info/patch.html#6

Great Pacific Garbage Patch- Good Morning America 2010 http://www.youtube.com/watch?v=uLrVCI4N67M&feature=player_embedded

http://www.youtube.com/watch?v=FrAShtolieg&feature=related