Highways in the Sea Chapter 9

Causes of Currents Three major factors drive ocean currents Wind Changes in sea level Ocean circulation causes slopes to develop. The steeper the mound of water the larger and faster the current Variations in water density

What is a gyre? Large persistent currents in the ocean eventually run into land. The combination of the westerlies pushing water eastward, the tradewinds pushing it westward near the equator, and the Coriolis effect results in a circular flow in each ocean basin; a gyre.

How many gyres are there, where are they? There are 5 major gyres, one in each major ocean basin For those living in the United States, the North Atlantic Gyre is perhaps the most familiar as well as one of the most studied

What is the Ekman transport? is the natural process by which wind causes movement of water near the ocean surface. Each layer of water in the ocean drags with it the layer beneath. Thus the movement of each layer of water is affected by the movement of the layer above, or below in the case of a frictional bottom boundary layer

What are Geostrophic currents All five oceanic gyres behave like the Atlantic Gyre. These gyres are called geostrophic currents Geostrophic means related to the Earth’s rotation.

The Gulf Stream (10,000 niagra falls worth of water per second) The narrowest, fastest, and deepest surface currents are the western boundary currents. (found on the east coast of continents) The Gulf Stream (~4 mph / 7 kph) in the North Atlantic is a great example of a western boundary current. Western boundary currents moves water from the equator towards the poles. Part of the global conveyer belt of heat. Day After Tomorrow…science or psuedoscience?

Global Conveyer Belt of Heat

The thermohaline circulation The thermohaline circulation is sometimes called the ocean conveyor belt, the great ocean conveyer, the global conveyor belt, or, most commonly, the meridional overturning circulation (often abbreviated as MOC). The thermohaline circulation (THC) is the global density-driven circulation of the oceans

What are Eddies? Friction with adjacent water can cause swirling currents, called eddies. Eddies can form large circular loops that break away as cold core or warm core eddies. Eddies are important because they can profoundly affect local temperatures and water conditions. Commercial fishing vessels use eddies to locate fish These currents also affect shipping by influencing ship speed. 200 kilometers / 320 miles across Water’s inhabitants???

What role do currents play in transporting heat What role do currents play in transporting heat? How do currents affect climate? Water’s high heat capacity is the reason that oceans affect weather and climate. Currents redistribute about a third of the heat in the tropics Without currents moving heat, the world’s climate would be more extreme

To be cont.