Ocean Currents

1. Ocean Currents The steady flow of ocean water in a prevailing direction

2. Ocean Currents • Driven by several factors • Tides • Wind • Thermohaline circulation

3. Tidal Currents • Occur with the rise and fall of the tides • Near the shore • Bays • Estuaries http://oceanservice.noaa.gov/

4. Coastal Currents • Depend on • Winds • Waves • Land formations

5. 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/

6. Surface Currents • Occur on the open ocean • Driven by a complex global wind system

7. 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/es1904/es1904page01.cfm http://www2.palomar.edu/users/pdeen/Animations/34_Coriolis.swf

8. Surface Currents – Coriolis Effect • Circulating air or wind is deflected by the Coriolis Effect http://oceanservice.noaa.gov/

9. 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