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Published byMeryl Jacobs Modified over 9 years ago
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Ocean Currents
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Why is Ocean Circulation Important? Transport heat Equator to poles Transport nutrients and organisms Influences weather and climate Influences commerce
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Surface Currents The upper 400 meters of the ocean (10%). Deep Water Currents Thermal/Salinity currents (90%) Ocean Currents
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Wind-driven surface currents
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30 o 60 o 90 o 0 o Forces 1.Solar Heating (temp, density) 2.Winds 3.Coriolis Surface Currents
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What do Nike shoes, rubber ducks, and hockey gloves have to do with currents?
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Lost at Sea
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January 1992 - shipwrecked in the Pacific Ocean, off the coast of China November 1992 - half had drifted north to the Bering Sea and Alaska; the other half went south to Indonesia and Australia 1995 to 2000 - spent five years in the Arctic ice floes, slowly working their way through the glaciers 2001 - the duckies bobbed over the place where the Titanic had sunk 2003 - they were predicted to begin washing up onshore in New England, but only one was spotted in Maine 2007 - a couple duckies and frogs were found on the beaches of Scotland and southwest England. Duckie Progress
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2004-2007 Barber’s Point
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Surface and Deep-Sea Current Interactions “Global Ocean Conveyor Belt”
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Transport by Currents Surface currents play significant roles in transport heat energy from equatorial waters towards the poles Currents also involved with gas exchanges, especially O 2 and CO 2 Nutrient exchanges important within surface waters (including outflow from continents) and deeper waters (upwelling and downwelling) Pollution dispersal Impact on fisheries and other resources
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Global ocean circulation that is driven by differences in the density of the sea water which is controlled by temperature and salinity.
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White sections represent warm surface currents. Purple sections represent deep cold currents
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Upwelling and downwelling Vertical movement of water Upwelling = movement of deep water to surface Hoists cold, nutrient-rich water to surface Produces high productivities and abundant marine life Downwelling = movement of surface water down Moves warm, nutrient-depleted surface water down Not associated with high productivities or abundant marine life
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upwelling downwelling
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El Niño-Southern Oscillation (ENSO) El Niño = warm surface current in equatorial eastern Pacific that occurs periodically around December Southern Oscillation = change in atmospheric pressure over Pacific Ocean accompanying El Niño ENSO describes a combined oceanic-atmospheric disturbance
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Oceanic and atmospheric phenomenon in the Pacific Ocean Occurs during December 2 to 7 year cycle Sea Surface Temperature Atmospheric Winds Upwelling
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Normal conditions in the Pacific Ocean
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El Niño conditions (ENSO warm phase)
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La Niña conditions (cool phase; opposite of El Niño)
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El Ni ñ oNon El Ni ñ o 1997
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Non El Niño El Niño Thermocline – layer of ocean right beneath the “mixed layer” where temperatures decrease rapidly. upwelling
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El Niño events over the last 55 years El Niño warmings (red) and La Niña coolings (blue) since 1950. Source: NOAA Climate Diagnostics CenterNOAA Climate Diagnostics Center
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El Nino Animation World Wide Effects of El Niño Weather patterns Marine Life Economic resources
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Effects of severe El Niños
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