South equatorial currents

From Glossary of Meteorology
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South Equatorial Current

(Abbreviated SEC.) The broad region of uniform westward flow driven by the trade winds that forms the northern part of the Southern Hemisphere subtropical gyres.

Being directly wind driven, the SEC responds quickly to variations in the wind field and is therefore strongest in winter (August). In the Atlantic Ocean it is found between 3°N and 25°S with speeds of 0.1–0.3 m s-1. In the Pacific Ocean it covers the same latitude band but attains 0.6 m s-1 and a transport of about 27 Sv (27 × 106 m3s-1) in August; this decreases to 7 Sv in February. In the Indian Ocean it occupies the latitude band 8°–30°S during the northeast monsoon (December–April) and expands northward to 6°S in September during the southwest monsoon, with speeds close to 0.3 m s-1 throughout the year.