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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.
2.
3.
4.
5.
6.
7.
North Atlantic
South Atlantic
North Pacific
South Pacific
Indian
Antarctic
Arctic?
Name the parts of the ocean
1.
2.
3.
4.
5.
6.
7.
North Atlantic
South Atlantic
North Pacific
South Pacific
Indian
Antarctic
Arctic?
Name the parts of the ocean
North Atlantic
South Atlantic
Arctic?
Antarctic
North Pacific
Indian
South Pacific
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/no
aa/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
The 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.
Gyres
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
Long term
Hourly
Daily
Weekly
Yearly
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
anomalies
Temperature anomalies
Rainfall anomalies