Ocean101-Ch08 - 1 Chapter 8 Chapter 8 Oceanic Circulation...

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Unformatted text preview: 1 Chapter 8 Chapter 8 Oceanic Circulation Chapter 8 - Oceanic Circulation Chapter 8 - Oceanic Circulation 1. 1. Studying ocean currents Studying ocean currents 2. 2. Surface currents & gyres Surface currents & gyres (wind-driven) (wind-driven) & Effects on climate 3. 3. Upwelling & Upwelling & downwelling downwelling Coastal El Nio & La Nia 4. 4. Thermohaline circulation Thermohaline circulation Water masses Formation & downwelling of deep water The global heat connection Ocean currents move large Ocean currents move large amounts of water and heat amounts of water and heat Wind-driven surface ocean circulation Density-driven thermohaline circulation Both redistribute heat from warmer regions to cooler 1. 1. Studying Ocean Currents Studying Ocean Currents Direct measurement Flow methods Flow methods = Fixed instruments Float methods Float methods = Floating instruments (or floating objects) Indirect measurement Distribution of density Satellite data Doppler flow meter Chemical tracers Distinctive water masses 2 Flow Methods Flow Methods Measure the current as it flows past a fixed object Fig. 8.27c, p. 195 Float Methods Float Methods Depend on the movement of a free-floating object Drogue Drift current meter Unintentional Float Methods Unintentional Float Methods 3 There is a connection between the prevailing easterly & westerly winds (Ch. 7) and the oceans surface currents (Ch. 8) Prevailing easterlies & westerlies push the surface waters of the oceans around in big circles, called gyres gyres 2. 2. Surface Currents & Gyres Surface Currents & Gyres Surface Currents & Gyres Surface Currents & Gyres Surface Surface currents are currents are driven by driven by winds winds , particularly the prevailing easterlies & westerlies Gravity Gravity, friction friction, and the Coriolis effect Coriolis effect work with wind to create circular pattern of surface current flow in each ocean basin Gyres Water moves clockwise in the N hemisphere gyres, counter-clockwise in the S hemisphere gyres Fig. 8.2, p. 172 Surface-Current Gyres Surface-Current Gyres North Atlantic Gyre Fig. 8.3, p. 173 Gyres can be subdivided subdivided into distinct currents The 4 interconnected currents in the North Atlantic Gyre are the:- Gulf Stream Gulf Stream- North Atlantic Current North Atlantic Current- Canary Current Canary Current- North Equatorial Current North Equatorial Current Each of these currents has different flow characteristics and temperatures Flow Within Gyres Flow Within Gyres The Coriolis effect causes objects to move in R- curving paths in the N Hemisphere and L-curving paths in the S Hemisphere As the wind induces water motion at the surface, the Coriolis effect makes the water curve off and move at an angle to the wind Each subsequent layer of water below is driven by the movement of the water above, and so moves off at greater and greater angles to the wind direction Which hemisphere is...
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This note was uploaded on 01/31/2012 for the course SCIE 027 taught by Professor Edward during the Fall '11 term at Broward College.

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Ocean101-Ch08 - 1 Chapter 8 Chapter 8 Oceanic Circulation...

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