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| are masses of ocean water that flow from one place to another. They are either wind driven or density driven (wind driven currents move water horizontally and density driven currents move water vertically). |
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| another name for wind-driven currents (move water horizontally) |
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| another name for density-driven currents (move water vertically) |
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| (gyros = a circle) Large circular-moving loops of water that are driven by the major wind belts of the world. Subtropical gyres rotate clockwise in the N. Hemisphere and counterclockwise in the S. Hemisphere. |
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| a vertical movement of cold, deep, nutrient-rich water to the surface. |
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| is the vertical movement of surface water to deeper parts of the ocean. |
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| where the surface currents along the geographical equator cause and upwelling of cold, nutrient-rich water because the northern and southern currents meet. |
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| with winds from the north, Ekman transport moves the coastal water to the right of the wind direction, causing the water to flow away from the shoreline. Water rises from below to replace the water moving away from the shore. |
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| if winds are from the south, the Ekman transport st5ill moves the coastal water to the right of the wind direction but, in this case, the water flows toward the shoreline. The water stacks up along the shoreline and has nowhere to go but down. |
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Definition
| this is the water that circulates around the rotation center of the North Atlantic gyre. It can be thought of as a stagnant eddy of the N. Atlantic Gyre. (it is named from a type of floating marine alga called Sarassum that abounds on its surface). |
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| warm rings that contain shallow, bowl-shaped masses of warm water about 1 km deep, with diameters of about 100 km. Warm-core rings remove large volumes of water as they disconnect from the Gulf Stream. |
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| Cold nearshore water spins off to the south of the Gulf Stream as counterclockwise-rotating cold-core rings surrounded by warmer water. The cold rings consist of spinning cone-shaped masses of cold water that extend over 3.5 km deep. |
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Definition
| (also referred to as Deep-Ocean Circulation) deep currents occur in the deep zone |
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| Discuss the methods to measure surface and deep currents: |
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Definition
- Direct Methods –
1. Floating devices – i.e. radio transmitting float bottles.
2. Fixed current meter – i.e. propeller flow meters.
- Indirect Methods –
1. Pressure gradients – water flows parallel
2. Radar altimeters – satellites measure bulges in water.
3. Doppler flow meters – measure shifts in frequency.
Deep Currents –
1. Underwater float devices – Argo global network
2. Salinity Characteristics
3. Chemical Tracers – Tritium and CFC’s are examples |
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| Explain the origin of surface currents - |
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Definition
- Develop directly from the wind
- Extend to a max depth of 1 km
- 2% of the winds energy is transferred to the water. |
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| List the world’s five subtropical gyres – |
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Definition
1. North Atlantic Subtropical Gyre
2. South Atlantic Subtropical Gyre
3. North Pacific Subtropical Gyre
4. South Pacific Subtropical Gyre
5. Indian Ocean Subtropical Gyre
The center of each Gyre is located @ approx. 30° North or South Latitude. |
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| Describe the components of subtropical gyres (equatorial currents, western boundary currents, northern or southern boundary currents, & eastern boundary currents) |
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Definition
All gyres have the same components:
1. Equatorial Current
2. Western Boundary Current
3. N or S Boundary Current
4. Eastern Boundary Current |
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| Describe the Ekman spiral and Ekman transport |
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Definition
| Surface currents move @ an angle to the wind direction (think of a spiral) every layer of water is deflected approx. 45° (Northern Hemisphere = Right Deflection; Southern Hemisphere) |
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| Discuss the relationship between ocean currents and climate: |
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| The ocean temperatures drive the climate (think of how Western and Eastern WA are so different on either side of the mountain range, the ocean air is contained from the coast to the Mountains which is why it’s so green). |
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| Describe, in detail, the surface circulation patterns in (1) Antarctic (2) Atlantic, (3) Indian, & (4) Pacific: |
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Definition
(1) Antarctic –
(2) Atlantic –
a. N. Atlantic Gyre = N. Atlantic Current; Canary Current; N. Equatorial Current; Gulf Stream.
b. S. Atlantic Gyre = S. Equatorial Current; Brazil Current; West Wind Drift; Benguela Current
(3) Indian – S. Equatorial Current; Agulhas Current; West Wind Drift; West Australian Current.
(4) Pacific –
a. N. Pacific Gyre = N. Pacific Current; California Current; N. Equatorial Current; Kuroshio (Japan) Current.
b. S. Pacific Gyre = S. Equatorial Current; East Australian Current; West Wind Drift; Peru (Humboldt) Current. |
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| Explain the El Nino-Southern Oscillation and discuss its effects: |
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| The currents “flip-flop”, which results in the “Warm and Cooler” pools change position in the equatorial pacific. This Sothern Oscillation is what causes El Nino. This causes the temperatures to change in the continental regions to match the |
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| Describe the origin of thermohaline circulation and explain the worldwide deep-water circulation including the conveyor-belt circulation: |
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| These currents affect 90% of all ocean water. |
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| Due to the Eckman spiral clockwise rotation. |
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