surface currents flow of water in the uppermost layer of the ocean driven by wind

Surface CurrentsSurface Currents

Flow of water in the Flow of water in the uppermost layer of the ocean uppermost layer of the ocean driven by winddriven by wind

Wind and CurrentsWind and Currents

Strongly affected by the Strongly affected by the Coriolis Coriolis EffectEffect– The eastward rotation of earth on its The eastward rotation of earth on its

axis deflecting the moving water or axis deflecting the moving water or air away from its initial courseair away from its initial course

http://www.classzone.com/books/earth_science/terc/content/visualizations/es1904/es1904page01.cfm

Which direction??Which direction??

Wind PatternsWind Patterns

Driven by solar heatingDriven by solar heating– Warm at equator Warm at equator – Cold at polesCold at poles– Molecules move from warm to coldMolecules move from warm to cold

Also affected by moisture (density)Also affected by moisture (density)

As warm air rises at equator, new As warm air rises at equator, new air rushes in to replace it air rushes in to replace it wind wind

Formation of Trade Formation of Trade WindsWinds

There are 6 There are 6 atmospheric atmospheric

circulation cells:circulation cells:

Winds are bent by Coriolis Effect Winds are bent by Coriolis Effect (45(45oo))

http://www.mhhe.com/biosci/genbio/tlw3/eBridge/Chp29/animations/ch29/global_wind_circulation.swf

Surface CurrentsSurface Currents

Major wind fields create sea Major wind fields create sea surface currentssurface currents

Uppermost layer of surface water Uppermost layer of surface water moves at angle 45moves at angle 45oo due to Coriolis due to Coriolis effecteffect

Ocean Surface Ocean Surface CurrentsCurrents Trade winds move toward the Trade winds move toward the

equator, equatorial ocean current equator, equatorial ocean current produced move parallel to produced move parallel to equatorequator

Due to Coriolis effect, the surface Due to Coriolis effect, the surface currents combine into circular currents combine into circular systems systems gyres gyres– Northern Hemisphere – clockwiseNorthern Hemisphere – clockwise– Southern Hemisphere - Southern Hemisphere -

counterclockwisecounterclockwise

Ekman transportEkman transport

Top layer of water Top layer of water pushes on water pushes on water below it but below it but bends slightly to bends slightly to rightright

Processes Processes continues down continues down through water through water column creating column creating Ekman spiralEkman spiral

Effect of wind decreases w/ depth Effect of wind decreases w/ depth – Affects top 100 m (Ekman layer)Affects top 100 m (Ekman layer)– Overall Ekman layer moves at 90Overall Ekman layer moves at 90oo

from wind directionfrom wind direction

Effects of Ekman Effects of Ekman TransportTransport

Climate RegulationClimate Regulation

Water transports heatWater transports heat

Ocean Currents act like global Ocean Currents act like global thermostat:thermostat:– Solar heat from Equator carried to Solar heat from Equator carried to

higher latitudes warms poleshigher latitudes warms poles

– Cold water currents cool tropicsCold water currents cool tropics

Currents Affect Currents Affect OrganismsOrganisms Surface temp higher on western side Surface temp higher on western side

of oceanof ocean– Currents carry warm water away from Currents carry warm water away from

EquatorEquator– Tropical organisms found at higher Tropical organisms found at higher

latitudes on west side of oceanlatitudes on west side of ocean

Cold-favoring organisms live closest Cold-favoring organisms live closest to equator on eastern side of oceansto equator on eastern side of oceans