SIO40lecture9

SIO40lecture9 - SIO 40 Life and Climate on Earth Mon. Oct...

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SIO 40 – Life and Climate on Earth Mon. Oct 18, 2010 Lecture 9 – Oceans and Cryosphere
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Outline - Wind-driven circulation at the ocean surface - Ekman spiral - Current patterns - The oceanic pycnocline - Wind-driven upwelling and seasonal mixing - Circulation in the deep ocean - Thermohaline conveyor belt - Cryosphere
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ess.geology.ufl.edu/. . ./atmosphere.html Large-scale atmospheric circulation patterns (above) influence surface ocean circulation
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Interactions between wind and surface waters: the Ekman spiral Friction between the wind and surface water sets the water into motion, but Coriolis force deflects the water to the right (northern hemisphere) at about 45 ° . As each successive layer of water below the surface is also set into motion by friction, it is deflected progressively more to the right. When movement of all the individual water layers is summed together, the net transport of the upper water column is about 90 ° to the right. At some depth below the surface, the effects of wind-induced movement become insignificant. Sumich & Morrissey 2004
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The relationship between surface-current flow (black arrows) and ocean surface winds (blue arrows) is clear in the North Pacific. Continental boundary currents (dotted arrows) and counter currents (eg at the equator) result from the fact that water needs to flow away from areas where it tends to get “piled up” at the surface by the wind. Asia North America Sumich & Morrissey 2004
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Major ocean surface currents Ocean currents transport heat, altering regional temperatures. This helps cool equatorial regions and warm polar regions. Winds and ocean currents can also affect regional rainfall patterns. Warm ocean currents adjacent to land will create abundant rainfall, while cool ocean currents adjacent to land will create dry conditions (eg. Baja California).
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This satellite image of ocean surface temperatures (warm = orange/red, cold = blue/purple) in the Gulf Stream region of the North Atlantic shows that currents can have smaller (mesoscale) features like eddies and meanders as a part of the overall flow. Sumich & Morrissey 2004
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The pycnocline is a density gradient that inhibits mixing between the surface and deep ocean, creating a two-layered system. Note the contrasting properties of the surface and deep ocean in terms of nutrients and oxygen content. Vertical structure and mixing in the ocean
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Salinity refers to the salts dissolved in seawater. Changes in the salinity
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This note was uploaded on 05/02/2011 for the course SIO 40 taught by Professor Barbeau,k during the Fall '08 term at UCSD.

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SIO40lecture9 - SIO 40 Life and Climate on Earth Mon. Oct...

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