Unit 4 Lecture Notes - Oceanography 102 Unit III Study...

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Oceanography 102 Unit III Study Notes Oceans in a Warmer World: - absorbs/release heat/CO2 - current transport - increased evaporation from tropical ocean – warming/cooling, salinity effects. - Reduced reflection from reduced sea ice - Plankton: o Export carbon in tissues, skeletons to deep sea o Aerosol production o Acidification - Methane hydrates - Increased evaporation from Tropical Ocean o Water vapor is a major GHG warming effect o Increased clouds reflect sunlight cooling effect o Net effect unclear probably warming - Decreased “albedo” o Reduced snow and ice cover o Reduced reflection of solar radiation Warming effect positive feedback Reverse of “Snowball Earth” formation Oceans Role in Warming - Stores and transports huge amounts of CO2 and heat. o Conveyor belt moves heat from tropics toward poles Returns surface currents via Cape of Good Hope and Indonesia Mainly eddies, not directed flow o No net warming or cooling Conveyor Belt - most N. Atlantic deep water stays in Atlantic - water that does leave the Atlantic is well mixed with Antarctic water - water returns by a complex of eddies, not a linear conveyor. - Still transports heat into the subpolar N. Atlantic and salt out. Layers of Ocean - Up to 1km = central and equatorial H2O; Up to 2km = intermediate water - Deep water, and then bottom water - Persistent differences in temperature and salinity - Warm in upper 100m - Salinity higher in warmest and coldest water (because of evaporation and freezing) Convection in the Oceans - first described theoretically by Benjamin Thompson 1797 o had been observed 1751 by measuring cold temperatures a mile down in the tropics. o Must have been cooled at the poles and flowed at depth towards equator. o Otherwise water at equator would warm to the bottom. Flow in the Deep Sea - first believed to be slow and uniform current o North Atlantic water mixes upward to form Antarctic Intermediate Water. - 1 -
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NADW (North Atlantic Deep Water) Formation - cold, dense water and high latitudes sink to bottom - originates from cold Norweigian, Greenland and Labrador seas - largest is Greenland Sea. ABW (Weddell Sea water) Formation - Sea ice freezing increase salinity of remaining water - Density increases - Densiest water at Antarctica: Weddell Sea and Ross Sea Mean Deep-Sea Circulation - NADW flows long the bottom into the South Atlantic. o Average flow is flow (4in/sec, 0.25mph) - Weddell Sea Water (ABW) densest in oceans o Coldest water mostly confined to S. Atlantic. Thermohaline Circulation - driven by heat (and cooling) and salt - Gulf Stream transports large volume of warm, salty water poleward o Carries heat to high latitudes and keeps Europe temperate o Supplies salt that makes water denser when cooled. -
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Unit 4 Lecture Notes - Oceanography 102 Unit III Study...

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