oceans & coasts

outline the main causes of ocean currents…

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

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

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

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

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

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

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

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

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

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

what is thermocline?

temp decreases

what is halo cline?

salinity decreases

what is pcynocline?

density increases

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

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

what causes ENSO?

• sheer scale of pacific ocean

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