Pub. date: 2008 | Online Pub. Date: April 25, 2008 | DOI: 10.4135/9781412963893 | Print ISBN: 9781412958783 | Online ISBN: 9781412963893| Publisher:SAGE Publications, Inc.About this encyclopedia
Alexander Boris Polonsky
UPWELLING EQUATORIAL (UE) is upward water's motion in the upper layer of the Equatorial Ocean and occurs when a persistent easterly wind is blowing over the equatorial zone. Maximum upward velocity in the UE occurs just at the equator. UE is a result of the permanent divergence of a westward surface south equatorial current in the narrow equator vicinity, forced by the southeast trade wind. Divergence of westward current at the equator is caused by the change of sign of the Coriolis force between the Northern and Southern hemispheres. As a consequence of divergence, the upper thermocline becomes shallower at the equator. Strong permanent equatorial divergence also causes an intense entrainment of more cold water from the thermocline into the upper mixed layer. This leads to cooling of the upper mixed layer. As a result, the sea surface temperature is about 1.8 degrees F (1 degree C) lower in the ...