Ocean Currents

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Ocean Currents
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The Coriolis Force
The Coriolis force deflects objects (wind)
moving toward the Equator to the west
The Coriolis force deflects objects (wind)
moving toward the poles to the east.
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The Coriolis force deflects objects (wind)
moving toward the Equator to the west
The Coriolis force deflects objects (wind)
moving toward the poles to the east.
60o
30o
0o
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Ocean Currents
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Ocean Surface Temperature
40o F
90o F
40o F
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Ocean Currents
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Surface Currents
Forces
1. Solar Heating (temp, density) 2. Winds 3.
Coriolis
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Solar Heating and Density
Density
Mass (g) Volume (cm3)
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High density
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D m V
Expanding water (increasing volume)
low density
Ice density
Water expands as it is heated.
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Solar Heating
Heat expands water near the Equator
equator
N
S
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General Circulation
pole
Suns rays
Ocean
Earth
equator
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General Circulation (North)
Surface Water
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Winds Guide the Direction of Surface Water
Winds blow eastward between 0o and 30o latitude.
Rotation
30o
0o
30o
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General Circulation (North)
wind
Surface Water
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The Coriolis force deflects objects moving toward
the poles to the east.
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Winds plus Coriolis Force
East wind
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Winds plus Coriolis Force
The Coriolis force deflects objects moving toward
the poles to the east.
East wind
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Circulation
The Coriolis force deflects objects (wind)
moving toward the Equator to the west
East wind
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Atlantic Gyre
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Gyres
Clockwise current in Northern Hemisphere Counter
clockwise current in S. Hemisphere
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Temperature/Energy Transfer
Heat Capacity
cool
warm
cool
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Heat Capacity 1 cal/goC
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Deep Water Currents
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Deep Water Currents
300 ft
Low density
3000 ft

1. Temperature
2. Density

90 total volume
High density
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General Circulation
pole
Suns rays
Ocean
Earth
equator
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Rising and Sinking
pole
Equator
Density
Sinking
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Thermal Conveyor
Red surface
Mixing time of the Atlantic ocean 1000 years
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Two Major Currents
Gulf Stream Humbolt Current
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The Gulf Stream
1769
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The Gulf Stream
a river in the ocean
1000 x more water transported than the
Mississippi. 20 40 miles wide ½ mile deep 4
miles per hour
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Ireland England
Spain
cornwall
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The Humbolt (Peru) Current
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The Humbolt (Peru) Current
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Easterlies
desert
Cool water Cool air
Westerlies
7-8 C cooler than the ocean at similar latitudes
Dry conditions near the coast.
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Upwelling
wind
productive
Nutrient Source for Food Web
Basis for a rich fishing industry off Peru.
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Surge of Nutrients Food Chain
Phytoplankton constitute the food base of all
marine animals, are microscopic organisms that
inhabit only the sunlit uppermost oceanic layer,
using sunlight to photosynthetically combine
carbon dioxide and dissolved nutrient
salts. Zooplankton marine animals that rely
mainly upon water motion for transport.
Zooplankton subsist on phytoplankton and smaller
zooplankton. Nekton free swimmers, are
dominated by the bony and cartilaginous fishes,
molluscans, and decapods, with rarer mammals and
reptiles.
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Normal Conditions
½ meter
Cool water Dry air Low ppt.
Warm water Moist air High ppt.
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Abnormal Conditions
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Sustained Abnormal Conditions
Rain in desert areas
Warm water surge
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Abnormal Conditions
El Niño Spanish name for the male child
Sustained sea surface temperature anomalies
across the central tropical Pacific Ocean.
Initially referred to a weak, warm current
appearing annually around Christmas time along
the coast of Ecuador and Peru and lasting only a
few weeks to a month or more.
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El Niño
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Local Consequences (East)
normal
El Nino
Low Nutrient Levels
High Nutrient Levels
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Other Consequences
Floods Mosquitoes Disease
Droughts Fires
Peru Chile Interior
Indonesia Australia
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El Niño is driven by slackening of easterly winds
off the coast of Peru.
This results in less upwelling of
cool nutrient-rich water.
Persistent El Niño allows warm moist air to
persist near Peru leading to high rainfall in an
area that typically receives little rain.
Conversely, Australia and Indonesia experience
drought.
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Surface currents are driven by solar heating,
winds and the Coriolis force These forces produce
gyres that rotate clockwise in the N.
hemisphere. The Gulf Stream is off the coast of
N. America flowing toward Europe. It bring warm
waters to the north attenuating the effects of
latitude. The Humbolt current is off the West
coast of S. America It brings cool, nutrient-rich
water northward. Easterly wind off Peru push
water away from the coast producing
upwelling. The general result is high nutrient
contents and cool water near Peru. The water is
warmed as it moves west eventually supplying warm
water