oceans & coasts

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16 Terms

1
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outline the main causes of ocean currents…

  • prevailing winds blowing steadily across sea

  • dominant pattern of currents being clockwise in northern hemisphere & anticlockwise in Southern Hemisphere

  • effect of rotation of earth cause water in oceans to push westward, piling up water on western edge of ocean basins

  • return flow occurs as narrow fast-flowing currents

2
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explain the main causes of ocean acidification…

  • oceans acidity increases when ocean absorbs more co2

  • as more co2 produced from the Industrial Age, the more co2 is absrorbed by oceans lowering the ph resulting in more acidic water

  • beleived main causes is anthropogenic eg. carbon emissions from industrial plants, cars, planes etc

3
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outline the main impacts of ocean acidification on coral reefs…

  • ocean acidity increases, more coral reefs damaged or killed off

  • reduction in calcification and other calcifying organisms

  • causes slower growth & weaker skeletons

4
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explain the influence of ocean currents on energy transfers…

  • warm currents move water away from equator

  • cold ocean currents move water away from cold regions towards equator

  • eg. Gulf Stream transports 55 million m3 per second which warms western europe waters

  • north atlantic drift raises temps of nroth west, europe

  • labrador current reduces summer temps

  • eastern oceans experience upwelling where ocean currents move cold water, rich nutreints from ocean floor to the surface

5
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what is El Niño?

  • el nino: normal conditions are reversed, SST’s of over 28 degrees extend further across the pacific

  • low pressures develop over eastern pacific & high pressures over the west causing heavy rainfall in west over south america

  • western pacific eg indonesia experience warm, dry conditions

  • benefits US, less hurricanes & decreased storm activity

  • can be dangerous for indonesia as prolonged drought affects coffee production, forest fires, carbon release, spread disease

6
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what is La Niña?

  • intensification of normal conditions

  • strong easterly winds push upwelling water off coast of south america into western pacific

  • intermittent cold current flows from east over equitorial pacific ocean

    • impacts are not as severe as el nino but linked with unusual rainfall paters in Sahel ou

7
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outline main economic impacts of El Niño events…

  • causes drought for longer periods of time affecting crop growth eg. coffee, oil palm & hydroelectric production

  • decrease in production cause decline in indonesian economy as fail to meet normal standards

  • warmer temps risk reductions in Indian soya bean harvests, wheat in Australia & rice in china o

8
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outline main factors needed for development of tropical cyclone…

  • intense low pressure systems over tropical oceans

  • sea temp at 26.5-27 degrees, depth 60m

  • low pressure area has to be far enough from equator so coriolis force creates rotation into risin air mass

  • unstable conditions so air continues to rise

9
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identify main hazards associated with tropical cyclones/ hurricanes…

  • storm surges with hurricanes: abnormal rise of water generated by storm

  • heavy rainfall & flooding with cyclones: hold huge amounts of moisture which cools when it rises & condenses into heavy rain

  • flooding: storm losing strength as travels across land but continues to release masses of rain into streams, rivers, lakes & on land

10
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explain how oceans may be a source and sink of carbon…

  • sink: contains phytoplankton & other microscopic marine algae whihc absorbs 25% co2 emissions

  • turns co2 into organic carbon whihc settles into deep ocean

  • upper ocean has lower concentrations of co2 but if deep sea mixes with surface water the carbon could be churned upwards then becomes a source of carbon

11
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what is thermocline?

temp decreases

12
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what is halo cline?

salinity decreases

13
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what is pcynocline?

density increases

14
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how is freshwater seperated from sea water?

  • as sea water evaporates, salt remains behind, fresh water transferred from coean to atmosphere

  • region of excess evaporation eg. subtropics tends to become salty while areas of rainfall becomes fresher

  • sea ice formation removes freshwater from ocean, leaving behind more saline solution

15
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when does el nino phase start?

  • when trade winds die down or reverse direction allowing warm surface waters to more eastward

  • associated convection produces rain clouds over Peruvian & chilean coast

16
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what causes ENSO?

  • sheer scale of pacific ocean

  • planetory scale equitorial waves take time to corss pacific & ocean adjusts to wind variations slowly