Download Surface Currents - Lakeland Regional High School

Surface Currents
Flow of water in the uppermost
layer of the ocean driven by wind
Wind and Currents

Strongly affected by the Coriolis Effect
– The eastward rotation of earth on its axis
deflecting the moving water or air away
from its initial course

http://www.classzone.com/books/eart
h_science/terc/content/visualizations/e
s1904/es1904page01.cfm
Which direction??
Wind Patterns

Driven by solar heating
– Warm at equator
– Cold at poles
– Molecules move from warm to cold


Also affected by moisture (density)
As warm air rises at equator, new air
rushes in to replace it  wind
Formation of Trade Winds
There are 6 atmospheric
circulation cells:


Winds are bent by Coriolis Effect (45o)
http://www.mhhe.com/biosci/genbio/tlw3/
eBridge/Chp29/animations/ch29/global_wi
nd_circulation.swf
Surface Currents


Major wind fields create sea surface
currents
Uppermost layer of surface water
moves at angle 45o due to Coriolis
effect
Ocean Surface Currents

Trade winds move toward the equator,
equatorial ocean current produced
move parallel to equator

Due to Coriolis effect, the surface currents
combine into circular systems  gyres
– Northern Hemisphere – clockwise
– Southern Hemisphere - counterclockwise
Ekman transport


Top layer of water
pushes on water
below it but bends
slightly to right
Processes continues
down through
water column
creating Ekman
spiral
Effects of Ekman Transport

Effect of wind decreases w/ depth
– Affects top 100 m (Ekman layer)
– Overall Ekman layer moves at 90o from
wind direction
Climate Regulation


Water transports heat
Ocean Currents act like global
thermostat:
– Solar heat from Equator carried to higher
latitudes warms poles
– Cold water currents cool tropics
Currents Affect
Organisms

Surface temp higher on western side
of ocean
– Currents carry warm water away from
Equator
– Tropical organisms found at higher
latitudes on west side of ocean

Cold-favoring organisms live closest to
equator on eastern side of oceans