Embedded Files
https://www.chanthaburi.buu.ac.th/~wirote/met/tropical/textbook_2nd_edition/navmenu.php_tab_4_page_3.1.0.htm
https://www.madelinejameswrites.com/blog/ocean-circulation
https://polarpedia.eu/en/thermohaline-circulation-thc/
What is Oceanic Circulation?
What is Oceanic Circulation?
Oceanic circulation has two main components. The first is surface currents, which encompass the top portion of the ocean, about ten percent of the ocean as a whole. The second component are deep-ocean currents, which exist below the surface currents, encompassing about ninety percent of the ocean.
Surface currents are driven by atmospheric circulation. The combination of trade winds and westerlies creates a circular wind pattern which then creates surface currents. One of the main reasons why we have circular currents is a combination of the wind patterns and the water running into land. When the ocean currents run into land, the water is pushed around and away from the landform, out into open sea, until it runs into another landform, thus creating a circular movement of water.
Deep ocean-currents are driven by thermohaline circulation. The National Oceanic and Atmospheric Administration explains in their article, "Thermohaline Circulation," that "deep-ocean currents are driven by differences in the water’s density, which is controlled by temperature (thermo) and salinity (haline)"("Thermohaline Circulation"). This process results in a movement of warm and cold water.
This video essay goes more into depth about the 1992 Rubber Duck incident.
Fun Fact!
Fun Fact!
We have a shipment of rubber duckies to thank for our current knowledge of ocean currents.
In 1992, a shipping container full of rubber ducks and similar toys were lost overboard during a storm. The path that these ducks followed and the coasts they eventually landed on told us a lot about oceanic circulation.
Gyres:
Gyres:
2The National Oceanic and Atmospheric Administration(NOAA) explain in their article, "What is a gyre?" that "the ocean churns up different types of currents, such as eddies, whirlpools, or deep ocean currents" and that "larger, sustained currents...[have] proper names"("What is a gyre?").
There are five main gyres, which pretty much mirror the five ocean basins. These five gyres are in the Indian Ocean, North Pacific Ocean, South Pacific Ocean, North Atlantic Ocean, and South Atlantic Ocean. Within each gyre, there are a number of different currents.
The Southern Ocean is not an ocean basin, and therefore does not have a gyre. However, it does have an ocean current that wraps around the earth in an uninterrupted flow.
Ekman Transport
Ekman Transport
The Ekman Transport is an important aspect of ocean circulation.
The wind from atmospheric circulation blows across the ocean, creating friction. This friction causes the water to move, resulting in surface currents. Due to the Coriolis effect, the water moves at an angle to the right or left depending on the hemisphere.
In UCAR's article, "How Seawater Moves: Ekman Transport," they explain that "the speed and direction of the moving water changes with depth. Ocean water at the surface moves at an angle to the wind, and the water under the surface water turns a bit more, and the water below that turns even more"(UCAR). This creates what is known as the Ekman spiral. The resulting average moment from the spiral is what is known as Ekman transport.
The Ekman transport on a larger scale is what creates gyres.
Upwelling/Downwelling
Upwelling/Downwelling
This video explains upwelling and downwelling and makes some great connections to atmospheric circulation and marine resources.
https://dashamlav.com/upwelling-downwelling-definition/
http://oceanmotion.org/html/background/upwelling-and-downwelling.htm
These videos help to visualize important aspects of oceanic currents such as salinity and temperature. These are parcicularly important in thermohaline circulation.
Ocean Circulation on the Great Barrier Reef
Ocean Circulation on the Great Barrier Reef
https://charismaticplanet.com/life-on-a-coral-atoll/
http://nephicode.blogspot.com/2018/02/why-easter-islanders-did-not-sail-to.html
Ocean Currents
Ocean Currents
The Great Barrier Reef resides in the South Pacific Ocean and the nearest major current is the East Australian Current, or EAC. The current is named as such because it runs down the Eastern side of Australia's coast.
NASA's Earth Observatory explains in their article, "East Australian Current" that this current "is pushed to the western edge of the ocean by the rotation of the Earth" which results in a particularly fast and narrow current(Przyborski).
It is important to note that the EAC is named based on the landform it is next to, not the side of the South Pacific gyre it is on.
Thanks to Disney's 2003 film, Finding Nemo, many people already know about the EAC.
Bibliography for Oceanic Circulation
Bibliography for Oceanic Circulation
"Thermohaline Circulation." National Ocean Service, National Oceanic and
Atmospheric Administration, https://oceanservice.noaa.gov/education/tutorial_
"What is a gyre?" National Ocean Service, National Oceanic and Atmospheric
Administration, https://oceanservice.noaa.gov/facts/gyre.html.
Przyborski, Paul. "East Australian Current." NASA, Earth Observatory, 17 August 2005,
https://earthobservatory.nasa.gov/images/15366/east-australian-current.
UCAR. "How Seawater Moves: Ekman Transport." UCAR, 2008, https://scied.ucar.edu/learning-zone/earth-system/how-ocean-moves-ekman
Page updated
Google Sites
Report abuse