The Motion Of The Ocean

Nicheal Wiley 10-21-15 2nd period

Causes Of Currents

Ocean currents can be generated by wind, density difference in water masses causes by temperatures and salinity variations, gravity, and events such as earthquakes. Currents are cohesive streams of seawater that circulate through the ocean. Some are short-lived and small, while others are vast flows that take centuries to complete a circuit of the globe. There are two distinct current systems in the ocean- surface circulation, which stirs a relatively thin upper layer of the sea, and deep circulation, which sweeps along the deep-sea floor.

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Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water towards the ocean surface, replacing the warmer, usually nutrient-depleted surface water. The three main drivers that togther to casue upwelling are: wind, Coriolis effects, and Ekman transport. They operate differently types of upwelling, but the general effects are the same. The major upwellings in the ocean are associated with the divergence of currents that bring deeper, colder, nutrient rick waters to the surface. There are at least five types of upwelling: coastal upwelling, large-scale wind-driven upwelling in the ocean interior, upwelling associated with eddies, topographically-associated upwelling, and broad-diffusive upwelling in the ocean interior. Upwelling at the equator is associated with the Intertropical Covergence Zone (ITCZ) which actually moves, and consequently, is often located north or south of the equator. Upwelling intensity depends on wind strength and seasonal variability, as well as the vertical structure of the water, variations in the bottom bathymetry, and instabilities in the currents.


The Equatorial Counter Current is an eastward moving, wind-driven flowing 10-15m deep current found in the Atlantic, Indian, and Pacific Oceans. More often called the North Equatorial Countercurrent (NECC), this current flows west-to-east at about 3-10 degrees North in the Atlantic and Pacific basins, between the North Equatorial Current (NEC) and the South Equatorial Current (SEC). The NECC is not to be confused with the Equatorial Undercurrent (EUC) that flows eastward at the equator but some depth.

Cited From: http://en.wikipedia/wiki/Equatorial_Counter_Current

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