Class 23 GEOL 117
Note for Spring, 2004: Classes 23 and 24 were combined and presented on 17 March
and 29 March.
OCEAN CIRCULATION -- BASIC CONCEPTS
Wind-driven surface currents
Density-driven deep circulation
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OCEAN CIRCULATION – INTRODUCTION
1. Surface Currents
Horizontal currents: upper few hundred meters;
velocity = about 1 m/s
Driving force: prevailing winds
Modifying factors: deflection by ...
1) Coriolis effect
2) Continents
General pattern -- rotary circulation;
major gyres centered in sub-tropics
See Figures 7-14 through 7-17 in Thurman and Trujillo text
No need to memorize current names, except for a few that are clearly emphasized
in class later
The overall patterns is very important, though.
Atlantic -- rotary, or circular motion- the gyres (e.g., N Atlantic)
Equatorial currents
Gulf Stream
North Atlantic Drift –warms Northern Europe
Canary Current
North Pacific Ocean
- - California Current
- - Kuroshio Current
- - North Pacific Drift
- - polar currents (Alaska, Oyashio)
- - Equatorial Counter Current
2. Deep Circulation/Currents
Everything below upper few hundred meters
Driving force:
Sinking of dense water (e.g., N. Atlantic)
Review: What controls the density of the water?
Temperature-
Salinity (evap. and sea ice)
Pressure (???)- not important
