Oceans

Name the oceans

1.

2.

3.

4.

5.

6.

7.

Name the oceans

Just joking. There is only one ocean.

Name the parts of the ocean

1. North Atlantic

2. South Atlantic

3. North Pacific

4. South Pacific

5. Indian

6. Antarctic

7. Arctic?

Name the parts of the ocean

1. North Atlantic

2. South Atlantic

3. North Pacific

4. South Pacific

5. Indian

6. Antarctic

7. Arctic?

Name the parts of the oceanNorth Atlantic

South Atlantic

North Pacific

South PacificIndianAntarctic

Arctic?

Name the parts of the ocean

Statistics

• Area—~ 340 million km2 (71% of surface)

• Average Depth—3800m

• Salinity—35g salt/kg of ocean water (varies)

• Average Temperature--Surface: 17oC (63oF)

Deep: 3oC (37oF)

Temperature

• Where would you find warmer surface water?

Temperature

• Where would you find warmer surface water?

Cooler

Warmer

Cooler

Temperature

• Surface water is warmer than deep water

• From 200 m to 1000 m deep, temperature drops sharply.

• This region is called the thermocline

Density

• Surface water is less dense than deeper water

• From 100 m to 1200 m, the density rises sharply

• This region is called the pycnocline

What causes density differences?

What causes density differences?

Temperature and salinity

What causes density differences?

Temperature and salinity

Cooler water is

more dense

Saltier water is

more dense

Where will you find the saltiest surface water?

Where will you find the saltiest surface water?

Surface water in the tropics.

Evaporation is the highest there.

…but it’s warm water

Surface water near the poles.

Freezing sea water freezes the water and leaves the salt.

Why does ocean water move?

1.

2.

3.

Why does ocean water move?

1. Wind

2. Density differences

3. Coriolis effect

Why does ocean water move?

1. Wind—surface water moves in the

direction of the wind 2. Density differences

3. Coriolis effect

Why does ocean water move?

1. Wind—surface water moves in the

direction of the wind 2. Density differences—more dense water

sinks under less dense water 3. Coriolis effect

Why does ocean water move?

1. Wind—surface water moves in the

direction of the wind 2. Density differences—more dense water

sinks under less dense water 3. Coriolis effect—water flowing north or

south bends to the right in the northern

hemisphere.

Why does deep ocean water move?

Why does deep ocean water move?

• Density differences, mainly.

• Masses of water sink near the poles, traveling thousands of kilometers before mixing with other layers

• The tides also affect deep water.

The thermohaline current (deep)

Surface currents

Surface currents

Currents have to turn when they hit a continent

Surface currents

Cold currents come from polar waters

Surface currents

Warm currents come from equatorial waters

Surface currents

Currents heading towards the poles bend east

Surface currents

Currents heading away from the poles bend west

Surface currents

Currents circle clockwise in the northern hemisphere

Surface currents

Currents circle counterclockwise in the southern hemisphere

Warm currents include:

Warm currents include:

The Gulf Stream, Alaska, Brazil and East Australia Currents

Cold currents include:

Cold currents include:

The California, Peru, Canary and West Australia Currents

http://www.montereyinstitute.org/noaa/lesson08.html

Ekman Drift

• Winds blow east or west in bands by latitude

(PS: winds are named by where they come from)

Ekman Drift

• The water below the surface pulls to the right in the northern hemisphere

Ekman Drift

• Ekman drift causes a mound of water to pile up between the bands of wind.

Geostrophic Currents

• Coriolis forces and Ekman drift force water to move in a circle

• These currents are called geostrophic currents

Why does ocean water move?

1. Wind

2. Density differences

3. Geostrophic forces

4. Tides

Gyres

The circular pattern formed is called a gyre.

There are about 5 major gyres, and 10 minor ones

Gyres

Gyres carry heat around.

Trash collects in the center of a gyre

GyresThe speed of the water depends on the width of the current

It takes several years for water (and floating objects) to be carried around a gyre.

Upwelling and downwelling

• Ekman drift near a continent can move water away from shore. Water comes up from below to replace it.

Upwelling and downwelling

• Ekman drift near a continent can move water away from shore. Water comes up from below to replace it.

Reverse the wind, or place the continent on the other side to force downwelling

El Niño

El Niño

• …upwelling at the west coast of South America decreases…

El Niño

• …upwelling at the west coast of South America decreases…

• …leading to warmer surface waters…

El Niño

• …upwelling at the west coast of South America decreases…

• …leading to warmer surface waters…

• …reversing the prevailing winds…

El Niño

• …upwelling at the west coast of South America decreases…

• …leading to warmer surface waters…

• …reversing the prevailing winds…

• …changing rainfall and temperature patterns over the entire western hemisphere.

Walker Circulation

• Normal wind pattern

Walker Circulation

• El Niño events reverse the wind pattern

Weather vs. Climate

Weather vs. Climate

Short term Long term

Weather vs. Climate

Short term

Hourly Daily

Weekly Yearly

Long term

Over many years—using

historical or geologic

data

Weather vs. Climate

• Both include:– Total precipitation– Type of precipitation– Temperatures – Wind patterns– Seasonal variations in all of the above

Teleconnections

--when the cause is far removed from the effects

Teleconnections

--when the cause is far removed from the effects

With weather patterns:

-the position of the jet streams

-moisture content of air masses and

-temperature of air masses

can cause effects far away

Temperature anomaliesTemperature anomalies

Rainfall anomalies