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Equatorial Undercurrent

THE EQUATORIAL UNDERCURRENT (EU) is a strong subsurface equatorial eastward jet, which is situated under the surface of the westward south equatorial current in the Atlantic, Indian, and Pacific oceans. The main EU core (in which velocity exceeds 20 in. [50 cm.] per second) occurs within an equatorial thermocline. EU wideness is about 428 mi. (400 km.) (plus or minus 2 degrees to the north and south from the Equator). Thickness of EU varies from 656–1,312 ft. (200–400 m.). Typical maximum velocity within the EU core is about 3.3–5 ft. (1–1.5 m.) per second.

Two Primary Factors

There are two principal reasons for EU, namely the southeast trade wind blowing over the equatorial zone, and the convergence of equatorial eastward nonlinear current. Long-term southeast trade wind forcing, ...

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