Ocean Currents 101:

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Ocean Currents 101

• The Good, The Bad and
• !

The Ugly
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The Power of Ocean Currents

• Impacts Earths Weather Systems
• Vital to Maintaining Life on Earth!

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A review of the terminology

• High/Low Latitude
• Convection cell
• Albedo
• Coriolis Effect
• Pycnocline/Density

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A review of the terminology

• High/Low Latitude
• Convection cell
• Albedo
• Coriolis Effect
• Pycnocline/Density

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A review of the terminology

• High/Low Latitude
• Convection cell
• Albedo
• Coriolis Effect
• Pycnocline/Density

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A review of the terminology

• High/Low Latitude
• Convection cell
• Albedo
• Coriolis Effect
• Pycnocline/Density

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Extreme Albedo
0
50
100

• If Earth was covered in ice
• 84
• If Earth was completely covered by a dark green
  forest canopy
• 14
• A drop of as little as 1
• warming influence on climate
• roughly equal to the effect of doubling the
  amount of CO2 in the atmosphere

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BUTis Earths Albedo Changing?
YouTube - Amount of Arctic Sea Ice is Dropping
Each Decade (2008.09.17)
Remember for later An indication of warming
surface waters and fresh-water input.
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A review of the terminology

• High/Low Latitude
• Convection cell
• Albedo
• Coriolis Effect
• Pycnocline/Density

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Earths Big Picturewe live on a spinning planet

• Coriolis Effect changes the intended path of all
  moving bodies
• Affects both atmospheric and oceanic circulation
  processes

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The Coriolis EffectWhat is it?

• Caused by Earths rotation toward the east and
  its decrease in velocity with increasing latitude
• Motions are deflected to the right in northern
  hemisphere and left in southern hemisphere

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A review of the terminology

• High/Low Latitude
• Convection cell
• Albedo
• Coriolis Effect
• Pycnocline/Density

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T (Thermocline) H (Halocline) P (Pycnocline)
Low Latitudes
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Lets begin

• Ocean Circulation
• Consists of
• Wind-driven Surface Currents
• Density-driven Deep Currents

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Wind-driven Surface Currents

• Atmospheric Winds
• Created from uneven solar heating
• Earths Albedo
• Latitude

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Variations in Solar Absorption/Reflection Create
Convection Cells

• Atmospheric Low (L) occurs when warm, moist air
  (less dense) rises
• Atmospheric High (H) occurs when cool, dry air
  (more dense) sinks

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Creates Earths Major Surface Winds

• Tradewinds
• Low Latitudes
• Westerlies
• Mid Latitudes
• Polar Easterlies
• High Latitudes
• The Coriolis Effect gives it a twist to the
  right in the northern hemisphere and a twist to
  the left in the southern hemisphere

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Example of Important Surface Current Created by
Winds

• Trade Winds form the Equatorial Currents
• Travel westward until they reach the western
  portion of ocean basin (hit land)

This image shows cold water (purple) upwelling
near the coast of Peru and joining the South
Equatorial Current, which flows westward across
the Pacific Ocean
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Western Intensification and El Niño
The Power of the Ocean Impacts Earths Weather
Systems
A similar Western Intensification occurs in the
Atlantic Ocean
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2009 Hurricane Season

• More in the Pacific
• Note Atlantic Pattern

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Jet Stream Saturday, January 9, 2010
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Surface Currents Combine to create another
remarkable system

• Westward-moving Equatorial Current
• Hitting land and Coriolis Effect results in the
  Western Boundary Currents
• e.g., the Gulf Stream and Brazil Current in the
  Atlantic ocean

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And then

• Prevailing Westerlies (Mid latitude) form
  Eastward Surface Currents that are, again,
  deflected off the continents creating the Eastern
  Boundary Currents

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Together They Form an Ocean Gyre

• Combination of the Equatorial, Western Boundary,
  Prevailing Westerlies and Eastern Boundary
  Currents create a circular flow called a Gyre

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AND HERES THE UGLY!!
Click here Synthetic Sea - Plastic in the open
Ocean
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Density-driven Deep Currents
T H P
Low Latitude
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Average Ocean Depths
Atlantic 3500 m
Indian 3900 m
Pacific 4300 m
Changing ocean depths influence the direction of
flow.
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NowLets Connect the Oceans Surface Currents to
its Deep Currentsvia Downwelling and Upwelling
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T H P
Remember our Pycnocline at Low Latitudes?
Low Latitude
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How does it look in the Higher Latitudes?
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High Latitudes Important Areas of Ocean
Downwelling
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IMPORTANT REGION OF OCEAN UPWELLING
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Remember this?
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Putting it all togetherThe Conveyor Belt
Circulation

• A current that connects the Oceans Surface
  Waters to Deep waters via Upwelling and
  Downwelling
• Also called Thermohaline Circulation

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Putting it all togetherThe Conveyor Belt
Circulation

• THE GOOD
• Mixes waters within and throughout all oceans
• Oxygen flows down
• Nutrients flow up

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Putting it all togetherThe Conveyor Belt
Circulation

• THE BAD
• Its demise can result in global devastation!!

The Power of the Ocean Vital to Maintaining
Life on Earth!!
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Putting it all togetherThe Conveyor Belt
Circulation

• Due to
• Less-dense surface waters in High Latitudes
• Less-salty
• Warmer

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Putting it all togetherThe Conveyor Belt
Circulation

• Due to
• Less-dense surface waters
• Less-salty
• Warmer

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YouTube - GLOBAL WARNING - The Great Ocean
Conveyor and Potential Mass Extinctions
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• Vast majority of land was desert interior
• Increased volcanic activity
• Increased CO2 production
• Increased ocean acidification

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The Power of Ocean Currents
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Questions?