Equatorial current system
From AMS Glossary
equatorial current system
The system of ocean currents found in the upper Atlantic and Pacific Oceans between 20°S and 20°N.
Its major components are the westward flowing North and South Equatorial Currents (NEC and SEC), which occupy most of the region. The Equatorial Intermediate Current (EIC) is a subsurface band of intensified westward movement between 2°S and 2°N at depths between 300 and 1000 m. All other components of the system are narrow (200–400 km) bands of eastward flow: the North and South Equatorial Countercurrents (NECC and SECC), found at depths between 0 and 200 m and located between 5° and 10°N and 5° and 10°S, respectively; the Equatorial Undercurrent (EUC), found on the equator at a depth of 200 m; and the North and South Subsurface Countercurrents (NSCC and SSCC), found on either side of the EIC at depths between 400 and 700 m. The major elements of the equatorial current system, particularly the NEC, SEC, NECC, and EUC, are also seen in the Indian Ocean during the northeast monsoon season (December–April) but are significantly modified during the southwest monsoon season. In addition, the Indian equatorial jet is a feature not seen in the other oceans.