There are two types of ocean currents: surface currents in the upper 400m and deep water currents that make up 90% of the ocean. Surface currents are driven primarily by solar heating, winds, gravity, and the Coriolis effect. These primary forces start the water moving and secondary forces like the Coriolis effect influence the direction of currents. Gyres are formed from the interaction of winds and the Coriolis effect, creating circular ocean currents. Deep water circulation occurs in cold, salty waters and drives the global thermohaline circulation.

1. Ocean currents:

2. Current: Continuous and directed movement of ocean water

4. Two Types: Surface Currents Deep Water Currents

5. Surface Currents: 10% of water in ocean The upper 400m of the ocean

6. Deep water currents: 90% of water in ocean Waters move around the ocean basins by density differences Density differences a function of different temperatures and salinity

7. Two Types of Forces:Primary Forces: Start the water moving:Solar HeatingWindsGravityCoriolis EffectSecondary Forces: Influence where the current goes

8. Solar Heating: Causes water to expand Water is about 8 cm higher than middle latitudes, thus water wants to flow down slope

9. Winds: Winds blowing on surface of the ocean push the water Water piles up in the direction the wind is blowing

10. Gravity Will pull water “down the hill” when water mounds up

11. Coriolis Effect: An inertial effect due to the spinning of the earthWhen going towards pole you are coming from an area that is moving faster, thus the deflection with the direction of the Earth’s rotationWhen going to the equator, the deflection goes against the spin of the Earth, due to the spin of the Earth

12. Gyres: The effect of winds and Coriolis effect results in circular flows of water made of several currents

13. Ekman Transport: Surface water is blown away by winds, dragging the water beneath it The deflection due to Coriolis Effect creates a spiral pattern and a net current to the right or left of win Results in upwelling

14. Upwelling: Nutrient rich water from the deeper parts of the ocean rises to the surface to replace the water blown awayAnimation:

15. Deep Water circulation: Occur where the temperature is cold and relatively high in salinityThermohaline Circulation Thermo = heat, haline = salt

16. Earth Conveyor Belt Salt rich, warm water is blown north by the Gulf Stream, where is cools and sinks This provides heat to the polar regions and nutrients everywherePossibly disrupted by global warming

18. Local Currents: formed by a combination of tides, winds, waves, and rivers/streamsLongshore currents and rip currents

19. Longshore currents: When waves strike the shoreline at an oblique angle, causing resultant waves to move parallel with the shoreline

20. Rip Currents: Formed when waves push the water in front of it sideways till it can find a path out to sea