The steady flow of ocean water in a prevailing direction
Ocean Currents
 Driven by several factors
 Tides
 Wind
 Thermohaline circulation
Tidal Currents
 Occur with the rise and fall of the tides
 Near the shore
 Bays
 Estuaries
http://oceanservice.noaa.gov/
Coastal Currents
 Depend on
 Winds
 Waves
 Land formations
Coastal Currents
 Winds that blow along the shoreline—longshore winds—affect waves
and, therefore, currents
 Longshore currents are generated when a wave train reaches the coastline and
release bursts of energy
 May form rip currents (not rip tides) - a localized current that flows away from
the shoreline toward the ocean
http://oceanservice.noaa.gov/
Surface Currents
 Occur on the open ocean
 Driven by a complex global wind system
Surface Currents – Coriolis Effect
 Due to Earth’s rotation
 The Earth rotates faster at the Equator than it does at the poles

Earth is wider at the Equator; point on the Equator
has farther to travel in a day
http://www.classzone.com/books/earth_science/terc/content/visualizations/es
1904/es1904page01.cfm
http://www2.palomar.edu/users/pdeen/Animations/34_Coriolis.swf
Surface Currents – Coriolis Effect
 Circulating air or wind is deflected by the Coriolis Effect
http://oceanservice.noaa.gov/
Surface Currents
 Global winds drag on the water’s surface
 Caused movement in the direction that the wind is blowing
 Results in the deflection of surface ocean currents to the right in the Northern
Hemisphere (in a clockwise spiral)
and to the left in the Southern Hemisphere (in a counter-clockwise spiral)
 Called gyres
 Occur north and south of the equator
 Not at the equator

Coriolis effect is not present