ocean surface circulation
DESCRIPTION
Ocean Surface Circulation. Motion in the Ocean, Part I, or Why does the ocean have currents, and why do they move in circles?. Two types of Ocean Circulation:. Surface Circulation -- Wind-driven Deep Circulation -- Density (T,S) driven. Atmospheric Circulation. Temperature and Pressure. - PowerPoint PPT PresentationTRANSCRIPT
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Ocean Surface Circulation
Ocean Surface Circulation
Motion in the Ocean, Part I, or Why does the ocean have currents, and
why do they move in circles?
Motion in the Ocean, Part I, or Why does the ocean have currents, and
why do they move in circles?
![Page 2: Ocean Surface Circulation](https://reader035.vdocuments.us/reader035/viewer/2022062409/56814f33550346895dbcc72d/html5/thumbnails/2.jpg)
Two types of Ocean Circulation:
Two types of Ocean Circulation:
Surface Circulation -- Wind-driven
Deep Circulation -- Density (T,S) driven
Surface Circulation -- Wind-driven
Deep Circulation -- Density (T,S) driven
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Atmospheric CirculationAtmospheric Circulation
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Temperature and Pressure
Temperature and Pressure
As the Earth’s surface is heated, air is warmed, expands and rises (Low P)
Warm air carries water vaporIn the upper atmosphere the air cools and sinks (High P)
This round-trip is called a “cell”
As the Earth’s surface is heated, air is warmed, expands and rises (Low P)
Warm air carries water vaporIn the upper atmosphere the air cools and sinks (High P)
This round-trip is called a “cell”
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Things get interesting!Things get
interesting!On a rotating planet, moving objects appear to be deflected
Why is this?
On a rotating planet, moving objects appear to be deflected
Why is this?
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Coriolis Deflection (aka “I Could Care Less”
force)
Coriolis Deflection (aka “I Could Care Less”
force)Apparent force due to Earth’s rotation
Deflection in path of motion when viewed from a rotating reference frame
Gustave-Gaspard Coriolis (1835)Familiar from merry-go-roundsSignificant only for large distances (not toilets and billiards!)
Apparent force due to Earth’s rotation
Deflection in path of motion when viewed from a rotating reference frame
Gustave-Gaspard Coriolis (1835)Familiar from merry-go-roundsSignificant only for large distances (not toilets and billiards!)
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Coriolis DeflectionCoriolis Deflection
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Consequences of Coriolis
Consequences of Coriolis
Moving fluids (atmosphere and ocean) turn to the right in the Northern Hemisphere
Moving fluids (atmosphere and ocean) turn to the left in the Southern Hemisphere
Moving fluids (atmosphere and ocean) turn to the right in the Northern Hemisphere
Moving fluids (atmosphere and ocean) turn to the left in the Southern Hemisphere
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Global Wind CirculationGlobal Wind Circulation
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Wind-Driven Ocean Circulation
Wind-Driven Ocean Circulation
Steady winds produce waves and set the surface water in motion
Moving water is deflected to the right (N.Hemisphere) or left (S.Hemisphere)
This starts the main “gyre” motion of the surface ocean
Steady winds produce waves and set the surface water in motion
Moving water is deflected to the right (N.Hemisphere) or left (S.Hemisphere)
This starts the main “gyre” motion of the surface ocean
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Surface Ocean Circulation
Surface Ocean Circulation
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Main FeaturesMain Features
Five large gyresAntarctic Circumpolar CurrentEquatorial CountercurrentVelocities vary -- fastest are meters/sec
Five large gyresAntarctic Circumpolar CurrentEquatorial CountercurrentVelocities vary -- fastest are meters/sec
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106 m3/sec (Sverdrup) = all the rivers
106 m3/sec (Sverdrup) = all the rivers
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Gulf Stream - Benj Franklin
Gulf Stream - Benj Franklin
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Gulf StreamGulf Stream
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So, do the gyres just follow the
winds?
So, do the gyres just follow the
winds?Not exactly! But the winds get the motion in the ocean started
The oceans respond by flowing and turning
Water piles up in the center of gyres -- several meters high
Not exactly! But the winds get the motion in the ocean started
The oceans respond by flowing and turning
Water piles up in the center of gyres -- several meters high
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Ekman Transport -- moves water 90° to the
winds
Ekman Transport -- moves water 90° to the
winds
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Upwelling and Oregon’s Ocean
Upwelling and Oregon’s Ocean
Winter winds from the south -- downwelling
Summer winds from the north -- upwelling
Winter winds from the south -- downwelling
Summer winds from the north -- upwelling
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Winter SummerWinter Summer
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Global Wind CirculationGlobal Wind Circulation
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Geostrophic CurrentsGeostrophic Currents
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Coriolis deflection plus the Pressure Gradient steers the currents around
the gyres
Coriolis deflection plus the Pressure Gradient steers the currents around
the gyres
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Northern Hemisphere Gyres
Northern Hemisphere Gyres
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Surface CirculationSurface Circulation
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How do we track ocean circulation?
How do we track ocean circulation?
Fixed Buoys -- measure current speed and direction
Drifters -- travel with the currents and transmit their location
Fixed Buoys -- measure current speed and direction
Drifters -- travel with the currents and transmit their location
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Beach Swap Meets!Beach Swap Meets!
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Tracking Currents:The Story of the Lost
Nikes
Tracking Currents:The Story of the Lost
Nikes 1: 60,000 shoes spilled, May 1990
2-8: 1990-’91 9: 1993 10: 1994
1: 60,000 shoes spilled, May 1990
2-8: 1990-’91 9: 1993 10: 1994
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Marine Debris: Pacific Trash
Marine Debris: Pacific Trash
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.QuickTime™ and a
TIFF (Uncompressed) decompressorare needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.